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General Category => NC100, NC200, PCW, PDA600 - the rest of the Family! => Topic started by: Sebastian Blanco on 21:19, 01 July 16

Title: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 21:19, 01 July 16
Hi!, ok after my first pcw 6128 show up to be in bad conditions i was lucky and scored a PCW 8256 upgraded to 512.
Disassembled the guy a hooked a ribbon to a  external 3.5 drive burned cp/m floppy disks games and played for an hour all nice and dandy but .... ! then the unit suddenly turned off and never turned on again .... :'(

The computer don't even power up the power led is off all the time seem to be a power supply related issue.

Then i have an idea  :P get it to your local repair center!  ;D , so i go to a big repair shop i used to take stuff some years ago. But thinks changed a lot, then you have to see the face of front desk employee was like i have taken an alien artifact to the shop, he  called the manager and the manger stared at the PCW like he have seen Jesus Christ in person, then he call the shop owner from the back and when he take a look at the PCW his face was like "what the bloody hell is this thing".
Then i was friendly escorted to the exit door and get my ass kicked from the shop, so seem that I'm alone on getting the thing fixed :D.

Somebody now where i can start, or some common culprit on the analog board ?.

Thanks.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: GeoffB17 on 00:24, 02 July 16
Sad news.


When it 'died', was there any noise, or smoke, or smell?   If not, then it might be something minor, but you never know.


I'm sure there's folks here who will suggest what component may have died.


I have to admit, when I attached a 3.5" drive to my PCW, I never tried to use the PCW power supply.   I got an external 5v power adaptor, and I've always used that.   Never had any problem.   I always understood that the PCW power supply was weak, Amstrad used the 3" drives because their power requirements were lower than usual.


Best of luck.


Geoff
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: ||C|-|E|| on 01:08, 02 July 16
A very stupid suggestion, I know, but have you already checked the fuse?
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: GeoffB17 on 01:21, 02 July 16
If it's JUST the fuse, then maybe you could cure by using separate power supply for 3.5" drive, once fuse replaced.  I think I've read that 3.5" drive can take out fuse.   There are various models of drive, but maybe some take more power than others.   Maybe the one you have IS drawing too much power, and it managed for a while then went.
If there was no bang, or crack, or smoke, or smell, then the fuse is pretty likely.


Geoff
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: GeoffB17 on 01:29, 02 July 16
Just checked circuit diagram - there's a 2A fuse in one corner of the main PCB (near where mains comes in, I assume).   Check if that's OK.


Geoff
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Munchausen on 02:13, 02 July 16
Then i have an idea  :P get it to your local repair center!  ;D , so i go to a big repair shop i used to take stuff some years ago. But thinks changed a lot, then you have to see the face of front desk employee was like i have taken an alien artifact to the shop, he  called the manager and the manger stared at the PCW like he have seen Jesus Christ in person, then he call the shop owner from the back and when he take a look at the PCW his face was like "what the bloody hell is this thing".
Then i was friendly escorted to the exit door and get my ass kicked from the shop, so seem that I'm alone on getting the thing fixed :D .

This is such a funny image, it should be in a sketch show (I lolled)  :laugh:

We used to have a TV repair shop near by that probably could have fixed something like this. But they've all closed down. That one was an end of terrace house turned into a shop, now it's just an end of terrace house again, but with oddly large windows  ;D

I hope you get your machines fixed. If all else fails give @Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225) a shout. Just wait for him to soak all the water up in his basement with Plenty kitchen towels ("wettable, wringable, strong as bull") first.
 
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: CraigsBar on 03:20, 02 July 16



<snip>

I hope you get your machines fixed. If all else fails give @Bryce a shout. Just wait for him to soak all the water up in his basement with Plenty kitchen towels ("wettable, wringable, strong as bull") first.

I think Bryce has dried out again. The basement I mean. As my megadrive2 came back all crystal clear audio modded, country and 50/60hz switched, and most importantly with a mild CPU overclock (it now runs at 10mhz, not 7.16) and there is not a drip anywhere.

Craig.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 04:33, 02 July 16
Thank you guys for the reply, the funniest thing was that before going to the shop,  called and explained that the computer was very old and the complete unit was in the monitor that if they where sure that they still fix crt monitors, the clerk assured me that they can fix anything and there's no problem just bring it on. The guy when i was there confessed that he think it was a all in one imac or something like that :P.

The unit turned off next to me while i was using it and there's no smoke no sound nothing just the screen turn off.
I have checked the fuse and is ok, i have some electronic experience and studied tv and radio repairer when i was young, but that was like 20 years ago and have forgotten a lot.

The disk drive i connected just use 5v and i have disconnected the internal 3¨ considering the PCW can take 2 3¨ drives the load from a modern 3.5 drive sure could be a lot less than the original ones.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 04:46, 02 July 16
Hi Sebastian


Can you remove/Unplug both cables from the 3.5" drive and see if the unit powers up.


Also (Yeh i Know) Please check that the power plug has all the wires connected and that the power point has power going to it .


Good Luck      Ray



Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 05:23, 02 July 16
Yes i have tested removing all hardware possible, even the digial board but the unit never turn on
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Munchausen on 12:28, 02 July 16
Have you got a multimeter? First thing to check is the power rails
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 13:01, 02 July 16
Can you post some pictures of the component side of the PCB. The failure may be visible.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 02:43, 03 July 16
Ok get a multimeter to the job, using it i can get voltage even to the secondary on the isolation transformer that go between the high voltage area and the low voltage one but i´m working blind no shematics and no information off the correct voltages i have to find wat i can say for sure is that the rectifier diodes the fuse and resistors in the start of the circuit are ok.

Here go the pics

(https://s32.postimg.org/q7z1zbn7l/20160702_202419.jpg) (https://postimg.org/image/q7z1zbn7l/)

(https://s32.postimg.org/k8fw9ersx/20160702_202430.jpg) (https://postimg.org/image/k8fw9ersx/)

(https://s32.postimg.org/tu9gppiyp/20160702_202442.jpg) (https://postimg.org/image/tu9gppiyp/)

(https://s32.postimg.org/re7nbv0w1/20160702_202450.jpg) (https://postimg.org/image/re7nbv0w1/)

(https://s32.postimg.org/o8n1lni9t/20160702_202457.jpg) (https://postimg.org/image/o8n1lni9t/)

(https://s32.postimg.org/ws6fjeqm9/20160702_202507.jpg) (https://postimg.org/image/ws6fjeqm9/)

(https://s32.postimg.org/q2zw3e5a9/20160702_202547.jpg) (https://postimg.org/image/q2zw3e5a9/)

(https://s32.postimg.org/bxu31kw8x/20160702_202603.jpg) (https://postimg.org/image/bxu31kw8x/)

(https://s32.postimg.org/m96fu8ny9/20160702_202612.jpg) (https://postimg.org/image/m96fu8ny9/)

(https://s32.postimg.org/59xhezcqp/20160702_202619.jpg) (https://postimg.org/image/59xhezcqp/)

(https://s32.postimg.org/wlsqgbhhd/20160702_202625.jpg) (https://postimg.org/image/wlsqgbhhd/)

(https://s32.postimg.org/xcq1zu98h/20160702_202631.jpg) (https://postimg.org/image/xcq1zu98h/)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 02:52, 03 July 16
There is a service manual in the WIKI




Amstrad PCW 8256-8512 Service Manual (http://www.cpcwiki.eu/manuals/Amstrad%20PCW%208256-8512%20Service%20Manual.en.rar)


Good luck     Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 14:40, 03 July 16
I'll take a close look at the pictures later when I have time, however, the dust alone is enough to stop it from working. Give it a decent brushing with an unused paintbrush first.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: ||C|-|E|| on 17:18, 03 July 16
It is certainly a bit on the dusty side, to put it lightly  :-\ If I were you I would try to wear a mask (or a wet cloth over the mouth and nose) to prevent allergies and complications.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: SRS on 00:10, 04 July 16
Second picture looks "toasted". Whats on the other side ?
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Executioner on 01:48, 04 July 16
My 8512 has the same problem, but I bought it knowing it had the problem. No power indication at all. I need to extract the PSU soon and have a look, but I need to know how to avoid getting a shock from the monitor high voltage.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 11:22, 04 July 16
Second picture looks "toasted". Whats on the other side ?

That's the bottom side of the STK7308. That's a switching regulator and runs hot in normal use. It's also the most likely part to have failed (if the fuse is still good).

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 18:05, 04 July 16
Will try to get some compressed air can to wipe clean the board, but today as almost always is rainy like hell here.
 Also there a way to check if the stk7308 is bad i get the schematic from the part but is in Chinese you know a way to check for some expected voltages on the output or something.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: GeoffB17 on 18:47, 04 July 16
According to my service manual, voltages on the pins should be:


1: 0.2
2: -20.0
3: -27.5
4: 0
5: -9.0
6: 0
7: 0
8: -2.0
9: -3.0
10: 0
11: 0.24


14: 7.9
15: 7.9


Pin 1 is furthest from the edge of the pcb, pin 15 is nearest the edge.  Pins 1 - 11 are in a block, 14 and 15 are separate.


Geoff
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 01:01, 05 July 16
Check the voltage across C5005, but be careful poking around that part of the circuit, it can kill you. You should get about 220 to 240VDC. Then I'd check the voltages (Meter set to AC) across the inputs of T5001 (the transformer). If the STK is broken you are probably getting nothing or a DC voltage on the inputs.

If you're not sure about what you're doing, don't do it.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 22:04, 10 July 16
Thank you very much from your help, ok i checked the voltages across:
IC5001
pins from 1 to 13 i got 0v.
pin 15 is 304v DC.
pin 14 is 1000v DC and my multimeter get out of scale.
using the ground from the heat sink screws.

T5001
transformer input pins 1, 2, 3 got 313v DC using pin 4 as ground.

C5005
300v DC between pins

Seem the stk is death ass you say sir, but the high voltages on pins 14 and 15 are normal ?.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 02:58, 11 July 16
@Executioner (http://www.cpcwiki.eu/forum/index.php?action=profile;u=17)


If you want an STK7308 I have one here (Victoria) In a WORKING colour monitor board.
Cost " a Smile " .




Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 11:23, 11 July 16
Thank you very much from your help, ok i checked the voltages across:
IC5001
pins from 1 to 13 i got 0v.
pin 15 is 304v DC.
pin 14 is 1000v DC and my multimeter get out of scale.
using the ground from the heat sink screws.

T5001
transformer input pins 1, 2, 3 got 313v DC using pin 4 as ground.

C5005
300v DC between pins

Seem the stk is death ass you say sir, but the high voltages on pins 14 and 15 are normal ?.

Hmmm, the STK is most likely broken, but I'd also question your multimeters functionality. What model is it? Pins 14 and 15 are connected together both inside and outside the STK, so they can't possibly have different voltages.

My suggestion would be to swap the STK and all electrolytic capacitors around it. When you have the STK and caps off the board, check that the diodes are stilll doing their job.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: GeoffB17 on 18:18, 11 July 16
Well, I'd be interested to know what sort of thing might cause the STK to fail.


Something to be warned about??


Obviously, if it's just plain old age, will happen whatever at some point, then there's nothing I can do but keep fingers crossed.   I don't want my PCW to die!


Geoff
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 11:17, 12 July 16
The STK runs hot its entire life, so it's a part that's prone to fail. All that dust around it won't have helped either. Luckily they are still relatively easy to source at a reasonable price. You just need to make sure that you add thermal paste and bolt it securely to the heatsink when you replace it, otherwise the new part won't last very long.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: GeoffB17 on 14:18, 12 July 16
Thanks.


So, my PCW has NEVER been THAT dusty inside, and has ALWAYS had reasonable ventilation.  So I - hopefully - should worry less?


Geoff
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: ||C|-|E|| on 14:59, 12 July 16
That layer of dust can definitely make a big difference, if yours was always clean and well ventilated I would say that you could worry less, yes  :)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 16:59, 12 July 16
The capacitors around it are more likely to fail first.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 22:18, 15 July 16
@Executioner (http://www.cpcwiki.eu/forum/index.php?action=profile;u=17)


If you want an STK7308 I have one here (Victoria) In a WORKING colour monitor board.
Cost " a Smile " .




Ray

Thank you very much for your offer but theres no need for you ti kill a color monitor for this part seem to be quiet cheap on ebay i will go on and purchase one.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 22:21, 15 July 16
Hmmm, the STK is most likely broken, but I'd also question your multimeters functionality. What model is it? Pins 14 and 15 are connected together both inside and outside the STK, so they can't possibly have different voltages.

My suggestion would be to swap the STK and all electrolytic capacitors around it. When you have the STK and caps off the board, check that the diodes are stilll doing their job.

Bryce.

True bryce i check and rechecked the voltage across the pins and get this values, my multimeter is a very cheap chinise unit and i  have been using it from like 15 years. I will get a new better one and check again but i verified other sources like the main unit input and got 218v so seem to work OK.

Already purchased a new stk gonna change all the caps and check again after removing the stk
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 22:53, 31 July 16
OK have a news STK (not installed still) before i replace it i what to check so i don´t get it kill.
I have got also a brand new multimeter much better than the previous old one.
Lets see on pins 14 and 15 of the STK7308 got 305v DC on both pins. But 7.9v is what shows on the schematic i think must be something very wrong on another part of the circuit.
Also tested the big resistors the zener diodes and all the diodes in the input, and they seem to be fine removing one point and using the semiconductor test on the multimeter.
Got almost 0v on the q5001 transistor legs.
I´m not sure how the current from the input is drop from 308v(that is what i got DC at the end of the bridge diode) to 7.9 on the 14 and 15 pins.
Removed the dead STK7308 and tested again but got 305v on legs 14 and 15 still.

(https://s31.postimg.org/ofbmrkc1j/20160731_193307.jpg) (https://postimg.org/image/ofbmrkc1j/)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 03:15, 01 August 16
HI Sebastian.

The power supply circuit (DC) is floating above GROUND ? (It is AC coupled via C5013 to ground only)
If you do your measurements with respect to PIN 1 (-ve Lead (Black)) then to pin X that may help.


Please remember that this area is LETHAL

Good luck
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 03:25, 01 August 16
Thank you for your reply Audronic i have tried using the multimeter from pin 1 ground and pin 14 but i still got 306v like before.

HI Sebastian.

The power supply circuit (DC) is floating above GROUND ? (It is AC coupled via C5013 to ground only)
If you do your measurements with respect to PIN 1 (-ve Lead (Black)) then to pin X that may help.


Please remember that this area is LETHAL

Good luck
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 04:21, 01 August 16
Thank you for your reply Audronic i have tried using the multimeter from pin 1 ground and pin 14 but i still got 306v like before.
Hi Sebastian
I am not sure that i explained it OK.
Please try this:-
The Black Lead (-ve) on the Meter connect to PIN 1
and connect the Red Lead (+ve) to PIN 14.
Test the Voltage on DC


We are not testing to Ground.

Good Luck       Ray



Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 04:37, 01 August 16
I think i understand you correctly Audronic i take a picture in case i am metering it wrong.
(https://s32.postimg.org/b2fgf6or5/20160731_223211.jpg) (https://postimg.org/image/b2fgf6or5/)
 :o
Hi Sebastian
I am not sure that i explained it OK.
Please try this:-
The Black Lead (-ve) on the Meter connect to PIN 1
and connect the Red Lead (+ve) to PIN 14.
Test the Voltage on DC


We are not testing to Ground.

Good Luck       Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 04:49, 01 August 16
Hi Sebastian


Yes the points that you are using for testing are OK.
I forgot that you did not have the iC Connected..
I think that you will have to solder in the Chip WITH HeatSync compound, and the do some testing.


A picture that i am using ( I don't have a real Machine ) Please download it an see if that is the correct circuit.


Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 04:57, 01 August 16
Hi Sebastian


PS:-
If you follow the Positive line through the transformer to the Point 10 (Circled) and then to Pin 14 you will se that it is The output of the Diode Bridge 300 Plus volts
Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 05:04, 01 August 16
Thank you very much for your help, i see the same on the shematic i was just worried that i got 300v in place of the 8v that is show on the shematic i just don´t wanted to risk killing my new STK7308 gonna solder the new one and post the results  :o


Hi Sebastian


PS:-
If you follow the Positive line through the transformer to the Point 10 (Circled) and then to Pin 14 you will se that it is The output of the Diode Bridge 300 Plus volts
Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 05:38, 01 August 16
OK installed the new one and surprise ... 310v between pins 1 and 14 so another dead STK  :picard:
All the other pins got almost 0v
(https://s31.postimg.org/jo0qclyev/20160731_233537.jpg) (https://postimg.org/image/jo0qclyev/)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 02:38, 02 August 16
Hi Sebastian


Sorry i cannot help further


All of the components around the I/C will have to be checked.\


Good Luck    Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Executioner on 14:17, 02 August 16
@Executioner (http://www.cpcwiki.eu/forum/index.php?action=profile;u=17)

If you want an STK7308 I have one here (Victoria) In a WORKING colour monitor board.
Cost " a Smile " .

Ray

Hi Ray,

Sorry, I haven't been keeping up with this thread until now. I'm not sure that is the part I'm going to need as I haven't even looked at the board yet. Is that the most likely failed component?
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 01:26, 03 August 16
@Executioner (http://www.cpcwiki.eu/forum/index.php?action=profile;u=17)


By the look of the faults reported on the Forum it looks like thats the hardest working part.


Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: dlfrsilver on 18:02, 02 January 17
Yes i have tested removing all hardware possible, even the digial board but the unit never turn on


Those machines are VERY old. Check the fuse and also change all the capacitors. Those are more than likely prone to die since their old age.


Most retro hardware must be revised, you can't buy them and say "hey !! Let's power that or this up! ".


The joy won't last long. All the replaceable parts must be changed.


Please post a photo of your PSU belly open, and focus on the capacitor.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 11:56, 05 January 17
Regarding testing the power board, what is the safest way to run it under test without connecting to the CRT? Remove the flyback transformer?
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 13:01, 05 January 17
OK, I have got it upright and braced against the far end of the chassis with a wooden stick.


After replacing R001 (I found it was open circuit) I am seeing the same as Sebastian - 313v on pins 14/15 of the STK.


I found this interesting tidbit from the pages of an electronics trade magazine:


Amstrad PCW8256 We are beginning to get PCW8256 word processors back with power supply faults. The raster produced is small and the STK7308 chopper control chip IC5001 screams. All is returned to normal when the i.c. is replaced.

Suggests that it may be common, but we have a different problem. Already I tried to substitute the STK out of a working PCW into my broken one, but like Sebastian, this didn't fix it, and I have this nasty high voltage on pins 14/15. I am trying to find a datasheet for the STK that explains its inputs, but so far no joy (just short form sheets).


I also checked the voltages on Q001, they are all wrong (should be -2.0, -1.3, -2.0 and I have zero or mV type values).


The full measurements for the STK: I am getting 0v at pins 1-9, .46v at pin 10, 0v at pin 11 and 313v on pins 14/15, all WRT pin 1, which although connected to the heatsink, is not GND. WRT GND, I get -154v (1-11) and +154v (14/15).
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 14:50, 05 January 17
I have checked all resistors in the high voltage circuit RS001 - RS011 and they all match what the schematic says. No easy fix there.

Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: robcfg on 14:58, 05 January 17
Hi,


I just found that the NTE1870 may be a replacement for the STK, and its datasheet is much easier to find.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 17:09, 05 January 17
Nice one - downloading some stuff now :)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 19:20, 10 January 17
Quick update:


I acquired a bunch of STKs from ebay and resurrected the 8256 immediately. Now, the 9512 needs some other bits - C5006, C5007 & C5012 are replaced, and I am looking at Q5001, a D1207 transistor. I removed it from the board and did some tests with a meter that indicated something amiss, so I ordered one of those too. The only other parts around the STK that I would be concerned about are the diodes (normal and zener) but I can't seem to find them for sale. I will replace Q5001 and try it (as I have 2 spare STKs in case the new one I fitted gets fried like the one I took from the 8256)!


@Sebastian, if you're reading this, sorry for hijacking the thread. I think we have the same (or a similar) problem with our PCW power supplies, and I am hoping I can fix mine, then you can do the same. With a bit of luck we may get both of them running again.


 :)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 19:26, 10 January 17
OK installed the new one and surprise ... 310v between pins 1 and 14 so another dead STK  :picard:
All the other pins got almost 0v
(https://s31.postimg.org/jo0qclyev/20160731_233537.jpg) (https://postimg.org/image/jo0qclyev/)


Sebastian, it seems that this is normal. At least, the 315V rail is connected directly to pins 14/15 via the transformer. See the image I attached to the post below, it shows the circuit path. So maybe your STK isn't dead yet...


(edit: ..and if you look at the page immediately before the monitor schematic in the service manual, it says test point 10, which is connected directly to pins 14/15 of the STK, should have a waveform with a peak-peak voltage of 560v!)


Cheers
JonB


(Credit to jts1957 of http://www.tv-forums.com/ (http://www.tv-forums.com/) for the image.)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 23:01, 10 January 17
Give us real part numbers instead schematic numbers, then I (we) can check if we have spares we could send you. Q5001 means nothing, 2SD1207 means a lot.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 23:44, 10 January 17
Sure thing-


D5005, 5007 : RD3.6FB
D5006, 5008 : DFC10E-KB4


These are in the parts list on page 32 of the tech manual (and on the schematic). Problem is, I searched for "RD3.6FB" but no exact match.. Same with DFC10E or DFC10E-KB4.


Cheers
JonB


PS, as you can see, I am hoping Sebastian's (OP) PCW has the same fault. Sure looks the same... from what he's said..
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 05:26, 29 January 17
Dont´t worry about hihacking the thread i have given up on this, i have checked every component on the board and cannot find the fault, also show it up to some old tv technicians and them don´t seem to know what is failing i got pointed to try to change the flyback transformer but look like a hard to find part and a long shoot  :picard: .
But but but but ... like Jeff Goldblum could say found this thingy shematic:
(http://www.vcfed.org/forum/attachment.php?attachmentid=35730&d=1485427327)
on this forum:
http://www.vcfed.org/forum/showthread.php?55909-Amstrad-Schneider-PCW-IDE-drivers-an-interface/page2
Seem very easy to do, and for power i can just rig an atx power supply, and get rid of the monitor part, somebody have experience or information about this "video out mod" ?  :D
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 11:32, 29 January 17
I should do, it's my layout...  ;D


I use it on my PCW9512 along with a cheap hard disk power supply. You don't need one of those clunky ATx supplies for this. Let me take some photos and I'll show you.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 12:25, 29 January 17

OK Sebastien..


Power supply.


 [ You are not allowed to view attachments ]


This is a really cheap hard disk power supply, like this one http://www.ebay.co.uk/itm/191770678303 . It supplies 12v and 5v to the PCW. The PCW printer will not work with this, because it needs 24v. CCheck the connections on the 8256 before connecting it, you do not want to plug the 12v line into the 5v rail on the board...

Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 12:28, 29 January 17
Now the video adapter. You already have the layout. Here's the schematic.


 [ You are not allowed to view attachments ]


This is not my design, I grabbed it from another Amstrad web site. I do take some credit for the strip board layout and diagram which you already posted, though.


Top of the board.


 [ You are not allowed to view attachments ]


Bottom of board.


 [ You are not allowed to view attachments ]

Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 12:39, 29 January 17
You might also need the riser adapter, which is a bit of a hack. Its purpose is to lift the video adapter up a bit so that it doesn't foul any parts on the main board. If you choose to wire the video adapter to teh mainboard with a ribbon cable, then you don't need this.


 [ You are not allowed to view attachments ]


Wire the board and connect ground, green and composite video to the SCART plug. Make sure you use shielded cable for the green / composite lines and connect the shield of both to ground. You can use a probe clip to connect the 5v line of the PCW power socket to the +5v line on the adapter board. No need to worry about 0v (GND) because it's on the main board's video plug. Now plug the video board into the main board's video socket, like this:


 [ You are not allowed to view attachments ]


Connect the SCART plug to the TV and turn on. You may need to adjust the trimmer VR1 to get the right brightness.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 06:38, 30 January 17
What a surprise JonB such a small world indeed  :D .
Very nice board schematic must say, thank you for the information and the pictures i will build the board this week and test on.
My plan is to install the board on a prototype plastic box drop a pair of modded 3.5 floppy drives and live the good life. :P
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 08:34, 30 January 17
Leave some space in the the box for the IDE interface..


http://www.cpcwiki.eu/forum/nc100-nc200-pcw-pda600/who-wants-ide-drives-on-the-pcw/


 :D
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 04:32, 31 January 17
 :o cool do you already finished the design ?.
where i can get the pcb :D
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 11:14, 31 January 17

uIDE report
;D
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Gryzor on 16:07, 02 February 17
Public service token: here's a "μ" you can use to copy/paste and do it properly instead of using a 'u' :D
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 16:46, 02 February 17
It's a standard symbol on almost all keyboards: AltGr + m

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Gryzor on 16:49, 02 February 17
Oh, let's see: 


Hm, nothing for me, at least with US English set up at the office PC.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: robcfg on 16:56, 02 February 17
I have Windows in english with a Spanish keyboard and that doesn't work either.


I wish it worked, though!
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 17:01, 02 February 17
Strange, I have a German keyboard here and an English one at home and both work. The Lenovo Keyboard here even has the symbol printed on the keyboard key:

http://www.notebookcheck.net/fileadmin/_processed_/csm_Lenovo_Ideapad_Flex_10__12__2ee1d1bece.jpg

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Gryzor on 17:07, 02 February 17
Huh, interesting, indeed it does!! Of course there's also Alt+0230, but you need a numerical kb to easily use it.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: remax on 18:04, 02 February 17
In France, it's directly accessible with SHIFT+*


(http://static.ccm2.net/ccm.net/faq/images/0-Vuskup12-azerty-s-.png)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Gryzor on 18:49, 02 February 17
Strange, the choices made on international keyboards...
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 19:06, 02 February 17
Public service token: here's a "μ" you can use to copy/paste and do it properly instead of using a 'u' :D

"μ" normally means "micro", as in μF ("micro Farad"), but the "u" in "uIDE" means "Universal".
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 19:15, 02 February 17
Keeping it on topic for a moment. This won't be much help to Sebastien, but I managed to get my hands on a partially working power / CRT board for the 9512, so I might be back in business at some point soon. I would have liked to have fixed my board, but it is beyond my abilities. I even tried calling TV repair shops on the basis that the PCW's monitor is just like a TVs, but no one was interested... :(
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Gryzor on 09:31, 03 February 17
"μ" normally means "micro", as in μF ("micro Farad"), but the "u" in "uIDE" means "Universal".


Ohhh my bad then, thanks for pointing it out :)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 10:24, 03 February 17
Keeping it on topic for a moment. This won't be much help to Sebastien, but I managed to get my hands on a partially working power / CRT board for the 9512, so I might be back in business at some point soon. I would have liked to have fixed my board, but it is beyond my abilities. I even tried calling TV repair shops on the basis that the PCW's monitor is just like a TVs, but no one was interested... :(

There's still TV repair shops in existance near you?? Wow!  :o

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 12:45, 03 February 17
Seemingly, not. All the guys that could fix this are retired..


Meanwhile, the replacement turned up, but it, too, is dead. :(
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: ||C|-|E|| on 12:51, 03 February 17
Here near London I know a company that could repair it, but they would be charging much more than the PCW is worth. That is why, at some point, I decided to start working in the monitors myself.  It was that and maybe a lack of common sense.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 06:45, 05 February 17
The fun is back and this time is not the Atari 2600  :P

(https://s23.postimg.org/itb87pe7r/20170205_013445.jpg) (https://postimg.org/image/itb87pe7r/)

(https://s23.postimg.org/s2dehtn3r/20170205_013337.jpg) (https://postimg.org/image/s2dehtn3r/)

(https://s23.postimg.org/5ey5bo7jr/20170205_013329.jpg) (https://postimg.org/image/5ey5bo7jr/)

(https://s23.postimg.org/f0rpryypj/20170205_013322.jpg) (https://postimg.org/image/f0rpryypj/)

(https://s23.postimg.org/hw4syu2pj/20170205_013313.jpg) (https://postimg.org/image/hw4syu2pj/)

(https://s23.postimg.org/vebpb4euv/20170205_013305.jpg) (https://postimg.org/image/vebpb4euv/)

(https://s23.postimg.org/g6vpqrn07/20170205_013257.jpg) (https://postimg.org/image/g6vpqrn07/)

(https://s23.postimg.org/hn788wpx3/20170205_013252.jpg) (https://postimg.org/image/hn788wpx3/)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 14:47, 05 February 17
Nice one!


Hey, looks like you have an electrolytic cap for the chip smoothing. It doesn't really matter, but it's supposed to be a ceramic disc or tantalum cap.


Oh, also, I had an idea about how to resurrect these 9512s with monitor. Just need to examine the power board schematic. Don't throw any parts out yet!
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 20:03, 05 February 17
Yes i used an electrolytic cap,  but if it can affect video quality i can change it.
I have to test it using scart later.
Also i read on your post that your tv image look white not green maybe your tv is not selecting RGB mode and you are just looking at composite video for that reason you don´t see the green rgb line video.
If you find how to fix the monitor it will be great, but i have lost all hope.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 20:12, 05 February 17
It's fine, I prefer white.


I think we can get the proper monitor running, but I need to do some experiments first. If I'm right, I will post instructions. Keep all the parts!
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 12:22, 09 February 17
@Sebastian Blanco (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1801) : It's looking more promising. After a quick look at the monitor schematic, I can see it is powered from the 12v rail only (with an additional 5v line to power a single IC that the video signals go through). In fact, they could be separate PCBs! So if we remove all the components in the lower part of the schematic and fit a 12v / 5v power supply, mounting it on the board where the removed components were, we should be able to resurrect the PCW 9512 monitor. Isolating the mains supply is easy because it passes through an easily recognisable choke called L001. On one side of this is the power supply, on the other is the mains input, switch and fuse. So if we take the choke out and wire its input connections directly to our new power supply, we will benefit from the PCW's power switch and internal fuse circuit. When the PCW is reassembled, it will look completely normal.


Note: There is no 24v supply in this scheme (for powering the printer) but it could be added if a suitable 3 way power supply can be found (24v / 12v / 5v). In terms of power requirements, I would say you need 3A for the 12v supply, 2A for the 5v and 2A for the 24v.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 18:01, 09 February 17
JonB look like a good idea to try, looking at the regulator part in the schematic, seem not be to hard to do, just drop a small 12v 5v inside the case (there plenty of space) and bingo  ;D .

Looking at the 8256 shematic i think the choke is L4001 here.
The 5v volt regulator as you say goes to the sync ic on the top seem to be the only one that take 5v.
What i don't get is the 5v line change to 12v adj half way and then change back to 5v again.
(https://thumb.ibb.co/mBYATv/amstrad2.png) (https://ibb.co/mBYATv)


Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 18:54, 09 February 17
I meant to refer to L5001 which is the choke next to the power switch at the bottom left of the schematic.


The "12v adj" label is referring to the trimmer to the left of it. The line is 5v.

Anyway, all that old junk can be removed, so don't worry about it. But make sure the power cable that is plugged into to the main board is connected.

Oh, and the switched mode power supplies often have voltage trimmers on them, so I advise checking their outputs with a meter with a load, and adjusting where necessary.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 02:44, 10 February 17
Hey man you are a damn genius it seems to work, i just bridged 12v and 5v and gnd to the main board from an ATX psu.
And the monitor glow i can hear it also, still dont rewired the motherboard to the monitor but look promising  :P
https://ibb.co/cwP61F (https://ibb.co/cwP61F)
https://ibb.co/gKuaTv (https://ibb.co/gKuaTv)
(https://thumb.ibb.co/cwP61F/20170209_213732_1.jpg) (https://ibb.co/cwP61F)
(https://thumb.ibb.co/gKuaTv/20170209_211811_1.jpg) (https://ibb.co/gKuaTv)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 09:40, 10 February 17
Hmm, yeah. I though it might. Well done!


Now why didn't I think to use one of my XT power supplies for a quick test? Too busy with uIDE, I suppose... Anyway, I have ordered a 5v 8A / 12v 3A supply from eBay so I will be hacking the monitor board soon.


Meanwhile, how about a better tube? http://www.cpcwiki.eu/forum/nc100-nc200-pcw-pda600/pcw-8256-white-screen/ (http://www.cpcwiki.eu/forum/nc100-nc200-pcw-pda600/pcw-8256-white-screen/)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 17:25, 10 February 17
Right, then - let's give it a go!


I dismantled my machine and gave it all a good clean, including the CRT and boards. After the "massacre of the innocents" (removal of all High voltage parts of the circuit, as well as a bunch of other parts from the low voltage side), we have this:


 [ You are not allowed to view attachments ]


The space is for a drop-in 12v / 5v power supply which I have on order. The connections are as below - lft hand brown wire is 12v, right hand brown wire is 5v, blue wire is GND and the red jumper gets 12v to the CPU board's power cable to run the floppies.


 [ You are not allowed to view attachments ]
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 17:32, 10 February 17
Et voila!


 [ You are not allowed to view attachments ]
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 17:47, 10 February 17

There is still a problem though. The screen flickers on drive access. The monitor's 12v supply is connected directly to the motor power supply, maybe this is it. But the power supply has 8A. The 9512 supply is not the same as the 8256, see attached. The power lines are on sparate circuits. Maybe I took too much out. Or maybe I can fix it with a big smoothing capacitor. Any ideas?




9512 Power supply schematics:
 [ You are not allowed to view attachments ]
 [ You are not allowed to view attachments ]
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 19:50, 10 February 17
You can try using a choke to filter the line that go the floppy drive.
Also a simple one is just to use a small separated 12v supply for the disk drive.
Or use a more modern floppy drives the 3.5 ones I'm using only use the 5v line no need for 12v.

Or use caps filters on the floppy motors:
https://www.pololu.com/docs/0J15/9
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 19:50, 10 February 17
Must say you removed all that components quite fast what do you used ?.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 19:28, 11 February 17
Desoldering station. This one:


http://www.ebay.co.uk/itm/172508276166
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 20:42, 11 February 17
I have the cheaper version http://www.ebay.com/itm/30W-220V-Automatic-Electric-Suction-tin-Vacuum-Solder-Sucker-Desoldering-Pump-/271756761687?hash=item3f45f71a57:g:G44AAOSw-W5UyPqd
But have an eye on the bigger one like you got, much easier to clean that the self contained one.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 20:44, 11 February 17
its alive master its alive!
(https://thumb.ibb.co/fwFGka/20170211_153813.jpg) (https://ibb.co/fwFGka) (https://thumb.ibb.co/jsNwka/20170211_153802.jpg) (https://ibb.co/jsNwka) (https://thumb.ibb.co/cMAhQa/20170211_153754.jpg) (https://ibb.co/cMAhQa)
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 20:51, 11 February 17
What i can confirm is the same issue on the 12v line, if you load from the disk drive the screen flicker a little.
After running the amperimeter on the 12v line the monitor only load 0.9 amp, and this power supply have like 20 amps on the 12v so no overload. Probably just noise from the floppy motor.
Also the monitor only load a few miliamps  on the 5v so no problem.
The digital motherboard use 0.8 amps 5v.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 00:05, 12 February 17
its alive master its alive!


EXCELLENT IGOR! NOW PASS ME THE ELECTRODES!!! MWAHAHAHAHAHAHAHAAAAA!
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 00:06, 12 February 17
@Sebastian Blanco (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1801)


While we're on the subject, what's that isometric game you are running? And isn't it time you cleaned it?  :D
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: robcfg on 00:13, 12 February 17
The game is La Abadía del Crimen (The Abbey of Crime), which @Habi (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1314) ported from CPC to PCW.


It's the computer version of The Name of the Rose and a masterpiece of programming.


You should definitely check it, but it's though as hell, don't forget to get a guide  ;D
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 02:39, 12 February 17
Hahahaha yes need a good clean, but first i like to get my messy workbench clean off all junk and finish the revival.
Also yes it is abadia del crimen, i don´t understand the game a monk get to me and start to talk and then i loose.
Still trying to fix the motor interference to the monitor ,the funny thing is that this disk drive is only +5 but it make the monitor flicker when it moves. Looks like it pull low the power line low or something.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: 1024MAK on 13:50, 12 February 17
Try a filter, for example ceramic capacitor, high current inductor, and another ceramic capacitor.

Code: [Select]
                        L1
DC in ---------+-------mmmm-------+--------- out to device
               | C1               | C2
               =                  =
               | 220nF            | 220nF
0V in ---------+------------------+--------- 0V
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: 1024MAK on 13:53, 12 February 17
Use one filter between the PSU and the monitor circuitry, another between the PSU and the disk drive, for each supply line.


Mark
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 17:18, 12 February 17
Now that's interesting, Mark, I have one of those inductors that I pulled off the power circuit. It has 2 coils, 4 legs and is marked 1022C. It used to carry the mains voltage (live and neutral) to the power board. Might work?
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 07:28, 16 February 17
Hey jonb can you post the link to the psu you purchased for the PCW ?, i need to buy one.
The ones i got are quite nasty and very noisy.

Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 19:12, 16 February 17
This one


http://www.ebay.co.uk/itm/Open-Frame-Power-Supply-5V-8A-12V-3A-12V-0-5A-60W-/302221584948


But I haven't tried it yet.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 17:05, 17 February 17
I fitted the new power supply and it is working, but I still see motor interference.

I tried the circuit that Mark suggested, but it didn't help. Maybe because the inductor I used was the big one from the mains input line (I think it is L1 on the schematic).


@1024MAK how important are the inductor / capacitor values?

No interference with uIDE accesses though!
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: 1024MAK on 20:53, 17 February 17
Well, ideally you choose the values of the capacitors and the inductor to act as a blocking filter at the fundamental frequency of the interference. But that means finding out the frequency and doing the calculations. Search the Internet for "π-filter" (PI filter) and for "T-filter" for more info...

The mains choke that you have is not likely to be suitable. You need an inductor (a DC type that will not saturate with the normal DC current flowing) that can pass a high DC current (2A or more) with a high inductance. Go for a fairly high inductance value. Here are some examples from Farrell UK (http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&categoryId=700000005459&sort=P_PRICE&pageSize=25&showResults=true&sf=502,731&pf=110127171,110127172,110127243,110148614,110148616,110148617,110172601,110178564,110188286,110188935,110191129,110192850,111692488,111692495,111692502,111692510,111692513,111692518,111692520,111692523,111692527,111692529,111692532,111692538,111692542,111692544,111692547,111692551,111692553,111692629,111692634,111692638,111692641,111692645,111692651,111692656,111692660,111692666,111692676,111692728,112030504). Higher values of inductance are more effective for lower frequencies of interference.

You can also add low ESR 470uF electrolytic capacitors in parallel with C1 and C2 in my ASCII schematic shown above.

The filter cannot help if the interference is getting through via the 0V line.

Mark
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 20:58, 17 February 17
I fitted the new power supply and it is working, but I still see motor interference.

I tried the circuit that Mark suggested, but it didn't help. Maybe because the inductor I used was the big one from the mains input line (I think it is L1 on the schematic).


@1024MAK how important are the inductor / capacitor values?

No interference with uIDE accesses though!


A capacitor and a diode and you should be fine.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: 1024MAK on 21:50, 17 February 17
The problem is, without knowing what is happening electrically, any proposed solutions are guess work.
An "isolation" diode followed by a electrolytic "storage" capacitor may help if the problem is the PSU output voltage dropping (dipping) with a sudden high current load.

If this is the case, then a "star" wiring system may help as well. By this I mean, run separate wires from the PSU output terminals to the computer, another set for the monitor circuitry, and a third set for the disk drive power feed.

You may have to use all three ideas (filters, diodes, star wiring). If you do, the filter should be after the diode.

Mark


Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 00:34, 18 February 17
The problem is, without knowing what is happening electrically, any proposed solutions are guess work.


Understood, and sorry, I wasn't complaining, just reporting back.


I will have to explore these other options as I really don't want to be buying yet another power supply. I have all the parts scavenged from the PCW's power board, although I'm soon to be a bit busy sorting out these uIDE orders (quite a few of which need me to assemble....  ???

Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: 1024MAK on 02:34, 18 February 17

Understood, and sorry, I wasn't complaining, just reporting back.
Never said anything about complaining  :-\

Don't do a Beyoncé and put a ring on it, but do put a digital storage 'scope on it!  ;D

Mark
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 03:31, 18 February 17
@1024MAK (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1522)


What would be a suitable Digital Storage 'scope ?


Thanks     Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: 1024MAK on 03:42, 18 February 17
What would be a suitable Digital Storage 'scope ?
One that can capture a "waveform" using the "single trace" / "one shot" trigger (where you arm it, then when the 'scope senses the change in level for triggering, it records one "waveform" into it's memory). You can then view it on screen after the event.

Or are you asking which 'scope should you buy?

Mark
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 07:10, 18 February 17


Or are you asking which 'scope should you buy?

Mark

Hi Mark

Yes " Or are you asking which 'scope should you buy?"

Thanks    Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 11:15, 18 February 17
I can answer that: Rigol DS1054Z 4 channel scope with hackable firmware that upgrades it to a much higher specification that you normally have to pay four times the amount for.

Disclaimer: It's the only one I have direct experience with, but it seems like most people swear by them. Check out the eevblog forum, the "best scope" question comes up often.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 12:39, 18 February 17
Or the MSO Version. It's more difficult to hack, but it has a 16 channel Logic Analyser built in.

Bryce.

Gesendet von meinem Motorola DynaTAC 8000X mit Tapatalk.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Audronic on 00:28, 19 February 17
Thanks JonB - Bryce


I will have a look for them.


Ray
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: 1024MAK on 02:50, 19 February 17
I have a Rigol DS1052D Mixed Signal Oscilloscope and a PicoScope 3206MSO 200 MHz 2 Channel Pico PC Oscillosope

The PicoScope 3206MSO model that I have is no longer made, but later models are available.

I also have a 20MHz dual channel analogue 'scope and an earlier PicoScope model.

Mark
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 12:08, 19 February 17
I won't list all the scopes I have, but one of them is a Rigol MSO1104S-Z. It's hackable but the hack requires opening the scope and dumping the contents of the FPGA via JTAG, which most users probably won't be happy doing. I'Ve hacked mine, but even without being hacked, it has everything that you would need for retro repair and development.

Bryce.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 03:26, 20 February 17
I can confirm that using separated +12 and +5 psus fix the problem no interference at all.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 16:20, 20 February 17
Which ones did you buy?
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 00:14, 24 February 17
Just a pair of random switched psus pick them in a flea market, the 12v one is 3 amps and seem to be from a hard drive and the +5 also 3 amps switched.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 05:23, 26 February 17
(https://s27.postimg.org/5sihqu8xb/20170226_000320.jpg) (https://postimg.org/image/5sihqu8xb/)
(https://s23.postimg.org/arynyj7vb/maquina.jpg) (https://postimg.org/image/arynyj7vb/)

I have only to clean it now :P
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 05:38, 26 February 17
maybe this dc - dc filter can work to clean the 12v line.
http://www.ebay.com/itm/New-RTF-LC-FILTER-FPV-DC-Filter-Noise-Eliminator-for-RC-Quadcopter-Low-Cut-DIY-/201571234633?hash=item2eee94f349:g:QrYAAOSwO~hXIctE
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 12:43, 26 February 17
I have ordered one - we'll see if it works!
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 13:17, 26 February 17
How many amps does the system pull from the 12V rail? That filter will already be struggling at a little over 1A.

Bryce.

Gesendet von meinem Motorola DynaTAC 8000X mit Tapatalk.

Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 13:44, 26 February 17
The listing said it handles 2A, is that not enough, or are you thinking it's a piece of junk (per comments on the CPC5v thread, which I totally undertstand) ?


Anyway.. it doesn't cost much to try.
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Bryce on 22:08, 26 February 17
No, I was just asking how much current the PCW pulls from the 12V rail. If it's less than 1A, then this device will be fine (assuming it does what they claim), if it's close to 2A, then the device won't be much help.

Bryce.

Gesendet von meinem Motorola DynaTAC 8000X mit Tapatalk.

Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: JonB on 23:45, 26 February 17
I'll let you know in a month when it turns up.. :D
Title: Re: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O
Post by: Sebastian Blanco on 17:00, 27 February 17
I have check this on the 12v line from the PCW and it takes 0.9 amps for the monitor.