Hello chaps!
Well I got this 6128. I put it into the monitor to see if it would work. I put the volume up so I could hear if it was on. Whist on, the power light was okay for several seconds but no display would appear.
Then, the light went out and I could hear nothing. The computer seems to have gone.
If I turn off the monitor with the computer on, then turn the monitor back on, the light flashes once and I can hear a little click from the disc drive.
The same happens when the computer is turned on after the monitor has been off. Is it just static?
There did come with it a generic 5v power transformer, and when I use that the light does come on and there is a high pitch whistle. Is this side effect of the power adapter being incorrect or something else? The monitor works fine with my 464..
Or does it look like it is broken? :'(
Quote from: Blurredman on 08:38, 17 June 11
Hello chaps!
Well I got this 6128. I put it into the monitor to see if it would work. I put the volume up so I could hear if it was on. Whist on, the power light was okay for several seconds but no display would appear.
Then, the light went out and I could hear nothing. The computer seems to have gone.
If I turn off the monitor with the computer on, then turn the monitor back on, the light flashes once and I can hear a little click from the disc drive.
The same happens when the computer is turned on after the monitor has been off. Is it just static?
Or does it look like it is broken? :'(
it could be the power in the monitor itself.
disconnect the 12v cable, so cpc takes less from monitor.
or, if possible try it with an alternative monitor or power supply.
the monitors have something in them which fails with age (voltage regulator? transistor??). I remember it going on my monitor, and it would cause it to just shut off.
this would cause power problems.
another thing to check out, is the power switch on the cpc may be bad, it may need to be taken out, dismantled, and cleaned and then put back together - I have found this on one cpc, and when I cleaned it, it worked great after.
also clean the connectors for the power if you can.
another thing to also try is to clean the edge connectors just in case there is some kind of short on them.
Oh god, I think I just ffffed up the situation very drastically.
Looking at the supply that has been provided it seems to be the culplrit. It's 18v, and it's a pitty I didn't see that before I plugged it into the 464!
Now neither of thecomputers boot using normal monitors (i have a green screen too) and the only way to get them to boot would create a blank screen box in the centre of the screen using the other power adapter.
I have ffffed it ffffing up!! ffs. It looks like I have two dead CPC's, just. like. that. :'( :'(
Yes, that will have certainly killed them. The whistling sound was probably the transformer overloading as the current rose (because it was burning through the ICs), I doubt either are repairable at this stage. If you are really, really lucky, then only one component shorted completely and saved the others, but it would take some major work to find out what had survived and what's dead.
Don't plug them into the monitors any more, otherwise you'll have two dead monitors too.
Bryce.
18v into the 5v?
or 18v into the 12v?
I'm hoping you broke something that wasn't too important and which can be replaced.
blank screen box indicates crtc is probably working, z80 probably too.
not sure what could be wrong.
Well the 6128 is DOA, cost me a fair bit of money.
The 464's are common enough but it's just upsetting.
I've got two computers weighing a few lbs which ain't worth shit no more, minus expence.
Well the fact that the 18V was plugged into the 5V socket isn't good (I assume it was the 5V, because, (A) A 464 doesn't have a 12V connection, and (B) I assume the PSU had a plug and not a socket). However, if you are getting a box in the middle of the screen all may not be lost and they might be repairable, but it's not going to be an easy repair.
Bryce.
I may be able to modify my emulator to simulate this fault. it may give a better idea to what has gone wrong.
The problem is, the CPC doesn't have any power protection inside the keyboard, all the protections (Over-voltage and over-current) are within the monitor, so plugging 18V into the 5V socket supplied all the ICs with way too much voltage. The smoothing capacitors and resistors can all take 18V, but most ICs will burn through at about 7V. In the best case scenario, one of the cheaper and easily replaceable 74LSxx ICs went first (and quickly) causing a full short-circuit and saved the other IC's, but if the weakest link was the AY or any other custom IC, then it's not good.
There is a repair-service guy here (Spain or Portugal I think). Or if you like, you could send me the PCBs (not the whole CPC, case, Keyboard!) and I could take a look at whether there's anything worth saving.
Bryce.
Well, there happens to be the same model motherboard on ebay. I'm going to try and go for that, hopefully others on this forum and elsewhere don't have the same ideas. ::) ;D
The guy selling the 6128 covered himself well. :'(
Why was there a 18V PSU included with the CPC? Are you sure it really supplies 18V?
I just took a quick look through the Datasheets: The most likely candidates (what went bang first) are the ULA, Z80, CRTC and AY, followed by the Memory shortly afterwards, the ROM would fail next and the the 74 Logic ICs last. The fact that the CRTC still seems to work, would suggest that the Z80, ULA or AY has fully shorted and possibly protected the rest.
Bryce.
Quote from: Bryce on 10:14, 17 June 11
Why was there a 18V PSU included with the CPC? Are you sure it really supplies 18V?
I just took a quick look through the Datasheets: The most likely candidates (what went bang first) are the ULA, Z80, CRTC and AY, followed by the Memory shortly afterwards, the ROM would fail next and the the 74 Logic ICs last. The fact that the CRTC still seems to work, would suggest that the Z80, ULA or AY has fully shorted and possibly protected the rest.
Bryce.
I think the z80 must be working to some degree because it set up the crtc, and the gate-array too, because you are getting a display.
I think ay/memory could be bust... but I can't be sure for definite.
Quote from: Bryce on 10:14, 17 June 11
Why was there a 18V PSU included with the CPC?
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320710088078&ssPageName=STRK:MEWNX:IT (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320710088078&ssPageName=STRK:MEWNX:IT)
That's what it was. I assume any idiot who wanted to test something at least reads the power requirements and doesn't stick any old phone charger or whatever in it.
I only used it (and consequently blew my 464) because my dad said, surely try the power adapter supplied with it to see if it is the monitor at fault. God if I could turn back time!
I can only presume it would have costed too much money to standardise which voltage power female connector could fit which male plug, that hurts bad when things are the way they are! :'(
@Arnoldemu: Would the default settings of the CRTC not give a box? If not, then the Z80 and ULA might be OK, and if the box is blank/all one colour, that would suggest that the memory might have survived too, otherwise you would have random colours all over the place? So my bets are on the AY.
Bryce.
Quote from: Bryce on 10:30, 17 June 11
@Arnoldemu: Would the default settings of the CRTC not give a box? If not, then the Z80 and ULA might be OK, and if the box is blank/all one colour, that would suggest that the memory might have survived too, otherwise you would have random colours all over the place? So my bets are on the AY.
Bryce.
Assuming it's a standard CRTC (not a costdown; no idea what it defaults to), then defaults are all 0's for the registers with no hsync and no vsync, so you should expect a black screen if it's gone. To get a letter box z80 must have executed the rom enough to set it up. Also, crtc doesn't generate the video, the ULA does. So chances are that is working to some degree.
I would say at this point that neither machine even boot up (and therefore give a display at all) without the 18v transformer. Nothing appears at all using the proper 5v one..
Quote from: Blurredman on 10:34, 17 June 11
I would say at this point that neither machine even boot up (and therefore give a display at all) without the 18v transformer. Nothing appears at all using the proper 5v one..
ok, if the power light is on and the screen is black, then it could be anything at all.
R.I.P.
Well you can always use them for spare parts (as the original ebay seller suggested).
Bryce.
Quote from: arnoldemu on 10:38, 17 June 11
ok, if the power light is on and the screen is black, then it could be anything at all.
No power light. Or at least, only for a split second when you touch the switch.
I've just had another try (with the greenscreen)
And, the 464 does indeed power up with a box. All one colour, as far as i can make out between the verticle lines on such a screen..
BUT, this only happens when the computer is turned on BEFORE the monitor. If the monitor is turned on before the computer then nothing.
Unfortunately, the same does not happen with the 6128, it simply makes the screen flicker once (but brightly) when turning on. Either way, i'm going to be looking for a replacement board for the 6128.
A question however, would it be safe to be switching such chips you describe between the completely broken 6128 to the 464 in a hope that grasping straws, what might not work on the 464 works on the 6128? Or the fact that nothing comes on means that everything is gone?
Quote from: Blurredman on 10:47, 17 June 11
I've just had another try (with the greenscreen)
And, the 464 does indeed power up with a box. All one colour, as far as i can make out between the verticle lines on such a screen..
BUT, this only happens when the computer is turned on BEFORE the monitor. If the monitor is turned on before the computer then nothing.
Unfortunately, the same does not happen with the 6128, it simply makes the screen flicker once (but brightly) when turning on. Either way, i'm going to be looking for a replacement board for the 6128.
A question however, would it be safe to be switching such chips you describe between the completely broken 6128 to the 464 in a hope that grasping straws, what might not work on the 464 works on the 6128? Or the fact that nothing comes on means that everything is gone?
most of the chips are normally soldered except the z80 and perhaps gate-array.
you can't just swap the gate-array unless they are exactly the same model.
I wouldn't advise it either. The 464 may be repairable, but I think the 6128 may have been broken before it ever got to you.
Bryce.
Very well. I won't make it worse then :P
As far as the 6128 is concerned, I am trying to get a replacement mainboard.
As for the 464, the colour is constant but every few lines (2 or 3) there is a darker line. What does that suggest in terms of replacing chips?
Can you make a photo of the problem?
Quote from: arnoldemu on 11:26, 17 June 11
Can you make a photo of the problem?
On the colour monitor it just displays one colour and the monitor can be turned on before the computer and it will boot up (maybe a fault of the green screen) the lines are just the green screen type of display.
On the colour monitor it displays a dark turquiose type colour. But has a mix of colours in it to make it that. Looking closer it has yellow andmaybe green.
I don't have the convenience of a digital camera..
Got another 6128 today.
So I plug it into the monitor. Nothing, just a box.
Now, I have plugged both the new 6128 and the 464 i blew on the tv using the modulator, and they both show exactly the same thing, a red box in the middle..
I wonder which chip(s) is/are the culprit?
Well, here's some pictures. It's on a black and white TV, But you get the jist of it, I don't want to loose more technology :P
Those are pictures of both the 464 and the new 6128.
As you see it's just a box, on a colour TV it is a red box with blue background (on both the 464 and the 6128). And on a colour monitor it is a turquiose box with a black background.
It is hard to make out because of the sun.
(http://i56.photobucket.com/albums/g164/Blurredman/Picture001.jpg)
(http://i56.photobucket.com/albums/g164/Blurredman/Picture002.jpg)
It doesn't make any sort of sound when turned on.
Any ideas? Bryce suggested the RGB cable in the monitors having overcharge on them, and as such destroying the RGB connection on the board. Might this be the case? If so, how to fix?
I don't see the pictures.
I disabled the 8255/AY in my emulator. BASIC starts up. Keyboard is not responsive and no sound.
Screen will probably roll, colours are good. So it seems the 8255 may not be at fault here.
For 6128: Points towards ram/PAL (memory management chip within 6128). Really not sure what the problem is you are seeing.
EDIT: Now I do.
Try removing the PAL 16L8 from the 6128 motherboard, see if anything changes (I doubt it).
I have overridden it before (but then the machine is 64k only), will see if I can find my info.
There are some links on the board that can be joined to override it too, but mine is just stuffing some wires into the socket that is there.
Can you not see the box in the telly!?!
There is a box, nothing rolls or scrolls, I've described the colour in my previous post.
EDIT
Is the 16L8 (Mine says HAL16L8 BTW) the controller for the 2nd lot of 64k memory?
Quote from: Blurredman on 17:53, 20 June 11
Can you not see the box in the telly!?!
Is the 16L8 (Mine says HAL16L8 BTW) the controller for the 2nd lot of 64k memory?
The box is visible. It looks like the border is rendered, but not the bytes to be displayed on the screen.
And yes. The Pal chip controls the 2nd 64k on the 6128.
If you like to have in-depth info about these kind of chips:
http://en.wikipedia.org/wiki/Programmable_Array_Logic (http://en.wikipedia.org/wiki/Programmable_Array_Logic)
It also explains, albeit shortly, the difference between PAL and HAL (negligible IMO).
Well for large-scale industrial production the difference between PAL and HAL is minimal, but for a hobbiest there's a huge difference. HAL doesn't exist in the hobby world, whereas PAL can be really useful. And GALs are even more useful :)
Regarding Blurredmans broken CPC's, there's not a lot more he can do at this stage, there could be multiple problems, but without any measurement equipment, he has done all that can be done.
Bryce.
Hopefully some time in the next 24hours i'll have another 6128 (a third).
After buying a broken one, and breaking the 2nd. I'm going to pick this one up to see it working.
I have also measured the voltage of the monitor input cables and compared them to the two modulators I have.
The modulators show no voltage at all on any pins which I imagine to be normal being an input.
However the monitors show and output of 0.5V AC from the middle pin which I believe is the 'luminescence' pin? This must be the source of the two CPC's I have blown up.
What is this and can I be got rid of for future use without damaging more CPC's?
I've come into some good fortune, I've purchased two 6128's and a green screen. :o
All working except the usual disc drive issue.
Origionally I was there to pick up the one, but he offered the other for an extra note. So here we are.
Cool. Now stop plugging the other ones into anything! :D
Hope it didn't cost you too much. The lesson was expensive enough already.
Bryce.
Good cannibalising on CPC 6128 ?
RAM : get yours working CPC into the 256K world...AY : you can get a second one as extension, was done in a book...
Z80 : a classical CPU, perhaps to manage your new external soundchip arcade style ?
CRTC : some are good, others are bad, just make sure your working CPC has the best one.
;D
Anyway a second disk drive is always good too... even if 3".
Quote from: MacDeath on 23:32, 21 June 11
Anyway a second disk drive is always good too... even if 3".
I am planning the 5.25" route. Make use of my drives. Make a nice wooden case with switches for side and drive :laugh:
The ABBA switch will have to be on the CPC, not the drive. you need to access pins inside the CPC that don't go to the drive.
Bryce.
I want to know, does the new one work fine?
The various tutorials for fitting external disc drives aren't very detailed. As far as I was aware it was just an issue of touching pins 31 and 32 or something like that (haven't looked into it versy seriously yet) and I was wondering if that could be done by keeping just two card connectors and one pin connector. The pin connector being inside the box with wires from switches connecting to the various pins if that was possible. Am I right in thinking that there must be no twist in the cable at all aswel?
Yes arnoldemu, I bought two yesterday which work. Got one disc drive to work, but I have no flat belts for the others to work indefinately.
Quote from: Blurredman on 16:03, 22 June 11
The various tutorials for fitting external disc drives aren't very detailed. As far as I was aware it was just an issue of touching pins 31 and 32 or something like that (haven't looked into it versy seriously yet) and I was wondering if that could be done by keeping just two card connectors and one pin connector. The pin connector being inside the box with wires from switches connecting to the various pins if that was possible. Am I right in thinking that there must be no twist in the cable at all aswel?
Yes arnoldemu, I bought two yesterday which work. Got one disc drive to work, but I have no flat belts for the others to work indefinately.
For connecting my drives, I use an external pc power supply.
I use a PC floppy drive cable with the edge connector on it.
and a suitable 3.5" drive with ready signal.
All connected together very easily with no modification.
You bought two more? One has to admire your perseverance... :)
5"1/4 ? can you still find disk for those ? :o
QuoteYou bought two more? One has to admire your perseverance...
And also broke them...
No wonder CPC are getting that expensive these days... ;D
Quote from: MacDeath on 19:33, 26 June 11
5"1/4 ? can you still find disk for those ? :o
And also broke them...
No wonder CPC are getting that expensive these days... ;D
Sorry for breaking them, both were my fault, one by ignorance and the other by naivity. :'( The other was broken before I recieved it.
Sure 5.25" discs are around, I just bought a pack of 10 unopened for just over £5. Plenty on ebay, many unopened boxes. They're more fun then 3.5".
Thx to you my personnal collection got a recent raise up in value, the rarer the more expensive...
But pleaaaase, don't ever never put your hands on an Amstrad PLUS.
Those are already quite expensives. Why don't you just try ZX Spectrum instead ?
;D
/joke
I remember well my first PC AT286 EGA had both 3"1/2 HD (1,44meg) and 5"1/4 HD (1,2 meg).
This was a complete luxury at the time, i was the happy guy who could actually do copy from both format at school.
So most games ended in my hands (actually my brother's hand... he was the specialist, I was the snotling gamer...)
Also this was great compaired to Amiga500 or AtariST owners... my games could use far less disks...
Anyway, most commercial games actually used DD disks (720K.. often a pair.) because not everybody had good HD drivers.
Good point was that most PC/16bit games of the era didn't need you to be a Hacker, but to only have access to a Photocopy machine.
Anti-Piracy was mostly through some stuff in original documentation or perhaps also the LucasArt card Disks test.
Most PC from the time had only one format or the other... rarely both.
Also having them in HD...
5"1/4 in HD were cheap as hell and could easily and safely be carried inside hardcover schoolbook.
But on CPC, what is the max format you can get with 5"1/4 disks ?
360K? 1,2 meg ?
The sad part with Amstrad's 3" disk was the lack of DD (720k) but on some PCW. and those are said to have so issues when writing in Normal "simple" 2x180k (2x178K)...
anyway :
(http://upload.wikimedia.org/wikipedia/en/d/d3/Dontcopythatfloppy.jpg)
:D
Good post.
Why I use 5.25? Because I can, surely they're more fun to use then 3.5"? I have a 5.25" on my PC and a 5.25" on my CPC, I would be in the same situation if they were both 3.5".. Except, I have more unformatted and unused 5.25" discs then 3.5. Plus, if I used 3.5", i'd get confused as I have soooo many 3.5" floppy discs with different formats, for PC, for Acorn etc. :laugh:
This makes it simple, 3" and 5.25" are for Amstrad :P
Since I don't have ParaDOS or any thing like that, the Amstrad formats the floppy the only way it knows how! 180k per side. I have a switch on the 5.25" for it to read the other side so I don't have to punch holes in my floppies and possibly wreck them trying :)
The discs I am using however can be formatted as 1.2MB IBM as they're High density. I'll need to post some picks of the final product. I have been given one of those external USB disc drive bays, the 5.25" floppy drive is a tad long, but some sellotape over the holes will not make you think twice :laugh:
Okay, I managed to get a hold of my fathers digital camera, and using the colour monitor this is the result:
(http://i56.photobucket.com/albums/g164/Blurredman/P1060492.jpg)
(http://i56.photobucket.com/albums/g164/Blurredman/P1060494.jpg) (http://s56.photobucket.com/albums/g164/Blurredman/?action=view¤t=P1060494.jpg)
(http://i56.photobucket.com/albums/g164/Blurredman/P1060495.jpg) (http://s56.photobucket.com/albums/g164/Blurredman/?action=view¤t=P1060495.jpg)
Have you tried the little potentiometer at the rear of the monitor ?
The 6128 really does look dead.
The CRTC hasn't been setup, could be dead z80 or anything.
The 464 is alive enough to setup the crtc, but I really can't say what is broken.
Ok. So the monitor does work. That's a start.
Bryce.
It was the unsuccessful removal of the HAL/PAL chip that made it become a flickering mess instead of being what it was (a box like the 464). I did notice though on the 6128 that the CPU was indeed at an angle in the holder. But straightening it made it no better ::)
Yes bryce the monitor works, but with the already broken CPC's. I don't want to plug a working CPC into the monitor incase the monitor makes the CPC do as the broken ones do. ;)
Why did you remove the PAL, that would just disable the RAM.
If the monitor is producing that picture on a broken CPC, I very very much doubt, that it would damage a working CPC. But I'm not going to guarrantee it 100%. I'd go with 99.999% though.
Is that the monitor, that you think broke the others?
Bryce.
yes
Very strange indeed.
Bryce.
btw, when I removed the pal on my machine (which i did with it off and I did it very carefully, it gave the same result as on the 464).
same happens with a bad pal I think.
I then put some wires in to patch it to 64k and the machine booted.
I bought a new pal and put it in and the cpc worked.
so I was just wondering if this was the cause.
the crazy lines indicates the crtc has not been setup. all this is done in rom, so it seems either the z80 or the rom is stuffed or both.
Okay, so it's possibly the HAL chip or ROM. Obviously, the Hal is the cheapest and easiest to replace so i'll look into that first.
On the 464, what chip number is it?
It's very annoying this :laugh:
Okay everyone. I took a risk! And here we have it:
(http://i56.photobucket.com/albums/g164/Blurredman/P1060496.jpg)
The monitor WORKS! I know many one or two of you were thinking "how could he risk ANOTHER CPC" but, if I told you my heart was not beating as I was hovering over the power button I would be lying, and that shows that I do care!
Well congratulations! My 99.999% was only 0.001% wrong :D
I love the multimeter. You use retro test gear to repair retro computers, now that's what I call dedication.
Bryce.
P.s. Careful! There's some dodgy looking bloke hanging around in your garden! :D
Edit: This also means that it wasn't the monitor that broke the CPCs, it must have been something else....?
Quote from: Blurredman on 18:07, 28 June 11
Okay, so it's possibly the HAL chip or ROM. Obviously, the Hal is the cheapest and easiest to replace so i'll look into that first.
On the 464, what chip number is it?
It's very annoying this :laugh:
hal is on 6128 only.
for the 464, I would suggest the ram.
if you have a multimeter and you're not scared to use it, you could try using the "clock" function to see if some of the chips are alive by checking their clocks are ticking over.
EDIT: Looking at the picture I don't think that multimeter will be sufficient. sorry. I was thinking a slightly more modern one, one which can check frequencies.
@Arnoldemu: How did you program the PAL/HAL? Do you have the configuration file?
Bryce.
Quote from: Bryce on 11:25, 29 June 11
@Arnoldemu: How did you program the PAL/HAL? Do you have the configuration file?
Bryce.
I didn't. I bought one from ebay, and it's a miracle it worked!
I wish I had a configuration file to make another, but I don't think one exists, and I don't think the PAL is readable (I think it's been protected from reading)?
Well it's not that they are read-protected, more the fact that they just don't have a read function. Once the fuses have been set, the only way of finding out the configuration is by testing every possible input combination, creating a truth-table from the output results and then re-writing the fuse configuration file. A lot more work than it's worth.
Bryce.
Quote from: Bryce on 09:02, 29 June 11
Well congratulations! My 99.999% was only 0.001% wrong :D
Actually, your 99.999% was 100.00% wrong, but anyhow... :p
Oh, you got a kitty! :)
? Why was it 100% wrong? The monitor obviously didn't damage the CPCs.
Or am I missing the pun?
Bryce.
Nah was just kidding; it's philosophical: when you're wrong, you're wrong. Can't be half-pregnant, for instance...