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General Category => Technical Support => Topic started by: keropi on 00:39, 17 June 16

Title: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 00:39, 17 June 16
Hiya...


well... I accidentally powered on my 6128+ with a 9v PSU instead of the 5v one (polarity was correct though)  :doh:
And Now when I power the machine I get this screen:

(http://i.imgur.com/xbUANsW.jpg)


Any idea/guess of what I killed? I get this screen with the basic cartridge and a black screen with no cartridge in the slot.


TIA for any help/tips. Kinda bummed atm  :(



edit:
found Bryce's over-voltage guide (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/a-guide-to-over-voltage-on-a-cpc/), replace ram and hope for the best?  :-X
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: ||C|-|E|| on 01:14, 17 June 16
It has border, so I think that there is a good chance that the RAM is failing  :)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: chinnyhill10 on 01:20, 17 June 16
It has border, so I think that there is a good chance that the RAM is failing  :)


Yeah, looks like the RAM. I've got a Speccy here that has had its RAM fried by higher than expected voltage.


Can't remember the layout of the Plus machines, but do a quick check to see if any of the RAM chips are getting hot. All the failed chips in the Speccy were red hot after 30 seconds. May save you replacing the lot.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 01:36, 17 June 16
thanks for the replies fellows  8)
I will report back tomorrow morning - I just don't have the heart to try anything today...  gonna take the machine with me and open it up on my workbench at the office. I'll let you know how it goes, I really hope it's the ram... wish me luck!





Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 10:01, 17 June 16

Just had a look at the machine, I can feel one of the RAM chips (the outer left) getting really hot and this seems to affect the "Amstrad 40464" and 74LS38 ICs that are next to it. I have tested the 74LS38 and it checks out fine , it survived the ordeal.
I am in the process or removing all 4 ram ICs and putting sockets.
Sadly I have no 41464 ram chips in my stash, is there any other compatible part I could use? Maybe 2x larger ram chips instead of 4?
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 10:22, 17 June 16
Nope stick with 41464. They are quite easy to find. And pray that the ASIC hasn't been damaged because that's not replaceable. Then stand in a corner and hit yourself with a big stick for doing something so stupid to your plus! :D

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Duke on 10:34, 17 June 16
Isn't it possible to use the 41256 (it's lots cheaper overhere atleast <$1 pcs), according to RAM - C64-Wiki (https://www.c64-wiki.com/index.php/RAM) :
"If you need one of the 4164 chips, you can also use a 41256 instead. You have to solder a short piece of wire between pins 1 and 16 of that chip ...."
Of course thats for C64, but should be OK for CPC aswell, Bryce? Of course using same amount of chips (and wasting the remaining space of the chips).

I have to do a ram replacement to my 6128 aswell :)

Nope stick with 41464. They are quite easy to find. And pray that the ASIC hasn't been damaged because that's not replaceable. Then stand in a corner and hit yourself with a big stick for doing something so stupid to your plus! :D

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 10:35, 17 June 16
yeah... keeping same psus with different ratings at the same place is not a clever idea  :picard2:
This is what I fear , some custom Amstrad IC died. I have Z80s, AY and 74xxx here but if that large asic in the middle is fried then this is a lost cause. It doesn't seem to get any warm though, so there is still hope maybe  :-X
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 10:36, 17 June 16
Yes, that's possible, but having messy jumper wires in the CPC for the sake of saving a few cents? Up to you.

Bryce.

@keropi (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1781): I have labels on my PSU cables directly at the computer side plug with Voltage and polarity written on it. Too many similar PSUs that are all lying under the same desk.

The fact that you are getting the screen/border would suggest that at least some parts of the ASIC are still working.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 11:01, 17 June 16
Yeah well lesson learned. I was too lazy to put a label and thus I used another multi-purpose PSU that looks the same.
Since I don't have suitable ram here I'll just remove the damaged one and power up  to see if anything else gets really hot.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 11:41, 17 June 16
1 Stück NEC D41464C-10 DRAM 64K x 4 | eBay (http://www.ebay.de/itm/1-Stuck-NEC-D41464C-10-DRAM-64K-x-4-/231976644819?hash=item3602e2b0d3)

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 11:49, 17 June 16
I already found the auction for me, the one you linked Bryce has +12eur shipping cost to Greece...
KM41464AP-12 64Kx4bit MOS DRAM DIP 18 1PC | eBay (http://www.ebay.co.uk/itm/KM41464AP-12-64Kx4bit-MOS-DRAM-DIP-18-1PC-/321923624718)


I removed all ram, powered on and I don't get any IC with high temps. The only one that gets slightly warm (maybe 18~20 degrees? one just feels a really slight warmth when touching it) is the large asic. The screen I get now is the following with rolling garbage:


(http://i.imgur.com/DHl8V00.jpg) (http://imgur.com/DHl8V00)


I'd love to have some ram atm for testing - even with some patching but unfortunately I can't find any suitable. I am really curious whether the machine survived or not .
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 12:06, 17 June 16
You'll know soon enough when the RAM arrives.

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: ||C|-|E|| on 12:42, 17 June 16
About the RAM, the cheapest chips I found, by far, as these:

5PCS Dynamic RAM IC NEC DIP-18 UPD41464C-10 D41464C-10 UPD41464C D41464C | eBay (http://www.ebay.co.uk/itm/272081105571?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

5 for 1.96 pounds or 2 something euros including delivery cost. I used 2 of them the upgrade the 464 Plus and work well  :)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 13:47, 17 June 16
About the RAM, the cheapest chips I found, by far, as these:

5PCS Dynamic RAM IC NEC DIP-18 UPD41464C-10 D41464C-10 UPD41464C D41464C | eBay (http://www.ebay.co.uk/itm/272081105571?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

5 for 1.96 pounds or 2 something euros including delivery cost. I used 2 of them the upgrade the 464 Plus and work well  :)

Good price, but with 3 weeks delivery time, it's not for people impatiently waiting to find out whether their 6128+ is dead or not.

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: dragon on 14:04, 17 June 16
Quote
author=Bryce link=topic=12109.msg128710#msg128710 date=1466148127]


Nope stick with 41464. They are quite easy to find. And pray that the ASIC hasn't been damaged because that's not replaceable. Then stand in a corner and hit yourself with a big stick for doing something so stupid to your plus! :D

Bryce.

Well tecnically is replaceable, as is selling in donberg electronics or an alternative is sacrificed a gx4000.

Anyway, i not sure if is necesary a working ram to test some features of  the asic. Or at least with the minimum ram working of video memory page.

The test cartridge maybe not used ram, or at least very little.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 14:21, 17 June 16
Good price, but with 3 weeks delivery time, it's not for people impatiently waiting to find out whether their 6128+ is dead or not.

Bryce.


heh true, make that 5 weeks for delivery here - everything from the far East takes at least a month to arrive here  ;D
I am getting some loaner ram , I believe I'll know soon enough if the machine works or not.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: ||C|-|E|| on 14:25, 17 June 16
Good price, but with 3 weeks delivery time, it's not for people impatiently waiting to find out whether their 6128+ is dead or not.

Bryce.

Certainly true, I waited because I was not in a hurry, hehe  :) Good news is that it took less than three weeks, the modules were here in around 10 days. Still not good in you are in a rush, though...
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 14:28, 17 June 16
Well tecnically is replaceable, as is selling in donberg electronics or an alternative is sacrificed a gx4000.

Anyway, i not sure if is necesary a working ram to test some features of  the asic. Or at least with the minimum ram working of video memory page.

The test cartridge maybe not used ram, or at least very little.

I've mentioned this here before somewhere: Donberg DOES NOT possess any stock, they are a reseller of stock they believe exists somewhere in the world. They are a one/two person enterprise in a small office. Try buying one from them and see if it ever arrives.

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: ||C|-|E|| on 14:37, 17 June 16
A GX4000 would be the way to go, but the process is difficult. I would probably buy a new Plus if the ASIC was fried. Having somebody to remove it from the GX4000 and doing the transplant would be expensive, unless you are doing it yourself  :)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Dr Tiger Ninestein on 16:48, 17 June 16
So it's possible to take an asic from a gx4000 and put it into a plus?


I did wonder if this was possible but always assumed it had to be from another plus.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: TFM on 17:53, 17 June 16
1 Stück NEC D41464C-10 DRAM 64K x 4 | eBay (http://www.ebay.de/itm/1-Stuck-NEC-D41464C-10-DRAM-64K-x-4-/231976644819?hash=item3602e2b0d3)

Bryce.


Of course they are from .... Ireland!  :laugh: :laugh: :laugh:
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: ||C|-|E|| on 18:03, 17 June 16
So it's possible to take an asic from a gx4000 and put it into a plus?


I did wonder if this was possible but always assumed it had to be from another plus.

It is possible, but the chip is heat sensitive. The process of desoldering and putting it back would be not trivial, you need to have quite a lot of experience  :)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: dragon on 18:13, 17 June 16
I've mentioned this here before somewhere: Donberg DOES NOT possess any stock, they are a reseller of stock they believe exists somewhere in the world. They are a one/two person enterprise in a small office. Try buying one from them and see if it ever arrives.

Bryce.

Oh i not know that thanks for the info!

So it's possible to take an asic from a gx4000 and put it into a plus?


I did wonder if this was possible but always assumed it had to be from another plus.

Is the same chip. From plus to gx4000 only change how is conected phisically.

And today gx4000 is very easy to find new at least here in spain.



Anyway  respect to the electrocuted plus . You don 't have a  cartridge  with a socket eeprom or something.? I build a test cartridge time ago, only to a precaution if he or  the gx4000 fails.

Until you cannot view, you can deslize in the menus taking as referènce the cartridge in the winape, and try things as the sound or colours in the border.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 19:29, 17 June 16

Of course they are from .... Ireland!  :laugh: :laugh: :laugh:

Everybody knows that Bielefeld doesn't exist, but since when has it moved to Ireland???

Bryce.

Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: TFM on 19:50, 17 June 16
Everybody knows that Bielefeld doesn't exist, but since when has it moved to Ireland???

Bryce.


Look at the chips.  ;)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: gerald on 20:44, 17 June 16
I already found the auction for me, the one you linked Bryce has +12eur shipping cost to Greece...
KM41464AP-12 64Kx4bit MOS DRAM DIP 18 1PC | eBay (http://www.ebay.co.uk/itm/KM41464AP-12-64Kx4bit-MOS-DRAM-DIP-18-1PC-/321923624718)


I removed all ram, powered on and I don't get any IC with high temps. The only one that gets slightly warm (maybe 18~20 degrees? one just feels a really slight warmth when touching it) is the large asic. The screen I get now is the following with rolling garbage:


(http://i.imgur.com/DHl8V00.jpg) (http://imgur.com/DHl8V00)


I'd love to have some ram atm for testing - even with some patching but unfortunately I can't find any suitable. I am really curious whether the machine survived or not .

Have you checked the removed RAM 2 by 2 in the 1st bank socket (IC110 / IC111)?
With a bit of luck two of them are still OK and the plus only need the 1st bank to boot
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: TFM on 20:46, 17 June 16
At the Wiki I can't find a decent picture of the Plus PCB, only GX4000. Can somebody give a pointer? Just asking, because it may help here.  :)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: gerald on 21:01, 17 June 16
At the Wiki I can't find a decent picture of the Plus PCB, only GX4000. Can somebody give a pointer? Just asking, because it may help here.  :)
what's wrong with these (http://www.cpcwiki.eu/index.php/Mainboard_Versions#CPC_6128.2B) ?
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: TFM on 21:28, 17 June 16
what's wrong with these ?

They are perfect!!! I will add a link to the Plus page, so people can find it. Thanks Gerald!  :) :) :)


EDIT: Done.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 22:22, 17 June 16

Look at the chips.  ;)

Oh yeah, didn't notice that before :)

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 23:36, 17 June 16
Well, I hope it doesn't come to replacing the ASIC.... I have done some smaller pitch smd IC replacements in the past with my "good quality amateur equipment" (a 90eur weller soldering iron, quality flux, leaded solder - nothing special but nothing utterly crapish) but there were two important factors at play:
a. I could destroy the old IC (thus the pcb pads end up like nothing was ever soldered on them)
b. I had a brand new replacement IC


I am more than sure I can remove the old ASIC from my mobo and solder a replacement but I doubt I can successfully remove an ASIC from a donor board so that it won't have bent legs or heat damage with my current equipment. I do hope it doesn't come to this.


Atm all 4 ram ICs are removed and binned, sockets are soldered in their place and on Tuesday morning I will receive the loaner ram .
It is encouraging that with the dead ram onboard both the 74LS038s under it also became hot after a while but they test OK in my tester. The ASIC during that time didn't even come close to being hot so I do hope that the ram took all the stress... but there is no way of telling until the replacement ram arrives.


Oh the wait is killing me , like 9v on a 5v cpc  ;D ;D ;D
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 23:43, 17 June 16
The ASIC should be removed / soldered with hot air, not an iron. Get someone else to do it for you if it comes to that.

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: dragon on 23:47, 17 June 16
To the database, this guy fried the gx4000 with 11v in the 5v entrance.

Only ram and z80 die.

Repairing Console Amstrad GX4000 | nIGHTFALL Blog / RetroComputerMania.com (http://www.nightfallcrew.com/10/03/2013/repairing-console-amstrad-gx4000/)

You probably maybe have lucky.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 23:53, 17 June 16
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)
no guts no glory  :P


@dragon (http://www.cpcwiki.eu/forum/index.php?action=profile;u=251)
good to have a little more hope, I got some Z80s here as well, they are the TOSHIBA ones though like TMPZ84C00AP-6 and TMPZ84C00AP-8




If the 6128+ ends up being fine I'll open a thread about scart cable / non-amstrad monitor connection. With the help of a good friend I realized that using a TTL Sync as RGB-enable voltage is a really dirty thing that leads to image deterioration (especially on lcd panels) and TTL-luma isn't that great either ...  maybe someone has delved deeper into this , especially the ttl-luma output....
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Duke on 00:05, 18 June 16
I think the z80 will be OK, when it can setup the crtc (screen shot).
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: chinnyhill10 on 00:08, 18 June 16
To the database, this guy fried the gx4000 with 11v in the 5v entrance.



Really really common. Killed at least 2 of mine like that.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 11:57, 18 June 16
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225)
no guts no glory  :P

...and no ASIC if you butcher it with an iron! :D

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: dragon on 12:43, 18 June 16

Really really common. Killed at least 2 of mine like that.

And the asic survive?.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Duke on 12:49, 18 June 16
Completely agree, use hot air as Bryce said, atleast to remove it. I would use hot air to put it back it on aswell, but you can get away with using an iron and plenty of flux :)

...and no ASIC if you butcher it with an iron! :D

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 14:28, 18 June 16
well yeah, it's no brainer that you need a hot air station to remove a smd IC like the ASIC in order to trsansplant it afterwards.
I never said I could remove a working ASIC and then transplant it using only my soldering iron for both tasks, that would be quite impossible  :D 
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Duke on 17:04, 19 June 16
Good :)

Just replaced the ram on my cpc6128 that got 12V (grey screen of death) and it's fully working again. Only thing damaged was the RAM, hopefully you have same luck.
The RAM chips I got were V53C256P80L (41256) so just had gnd pin 1 (A8). This was regular CPC of course, not a plus.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: TFM on 19:27, 20 June 16
Didn't the guy who made the JustCPC once tell that he has an internet source for ASICs? Forgot his name, but can't hurt to get in touch with him - just in worst case scenario.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: gerald on 20:15, 20 June 16
Didn't the guy who made the JustCPC once tell that he has an internet source for ASICs? Forgot his name, but can't hurt to get in touch with him - just in worst case scenario.
Yes he (Piotr) said that he has a source. But that's all he said  ;D
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 10:40, 21 June 16
And he was probably talking about Dönberg too.

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: dragon on 11:50, 21 June 16
Should be more easy buy the rights to amstrad. Take the tapes from steve gane, and made a fpga that find one new.lol.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 12:47, 21 June 16
Time to update the topic, I just got the RAM ICs and gave the machine a quick test: it works fine  ;D


(http://i.imgur.com/pjJpnLo.jpg) (http://imgur.com/pjJpnLo)


(http://i.imgur.com/lM8F3LY.jpg) (http://imgur.com/lM8F3LY)


Luckily it was only the RAM that failed (don't know if it was only one or two all ICs, I just replaced them all) and it seems everything went back to normal.

Thank you all for your support, input and help!
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: robcfg on 12:52, 21 June 16
Congratulations, lucky man!  8)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: 1024MAK on 14:29, 21 June 16
Congratulations, lucky man!  8)
Yeah, what he ^ said  :laugh:

Mark

Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: ||C|-|E|| on 16:14, 21 June 16
Congratulations! It seems that the electrolytic capacitors in that Plus have been replaced as well  :laugh: and there is an extra red wire next to the LED connector, and probably an ABBA switch too somewhere, right?  :D
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: TFM on 18:37, 21 June 16
Glad to see it works again! As we say "Mehr Glück als Verstand". Hope it will never break again.  :)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 22:19, 21 June 16
@TFM (http://www.cpcwiki.eu/forum/index.php?action=profile;u=179)
thanks, I'll make sure the PSU won't be mistaken again  8)


@||C|-|E|| (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1447)


You Sir are correct  ;D


I replaced the caps when I got the machine, it just seemed a good idea to replace the ones after the power input and then I just decide to replace them all with chemicon/panasonic ones as there are not that many to begin with...


There is indeed an ABBA switch under the 3.5" floppy:


(http://i.imgur.com/YccWcVa.jpg) (http://imgur.com/YccWcVa)


And this is the red wire deal:


(http://i.imgur.com/OCwY5za.jpg) (http://imgur.com/OCwY5za)


(http://i.imgur.com/ipKKbhB.jpg) (http://imgur.com/ipKKbhB)


I have installed a small switch above the power input , after discussing the video quality issues with a good friend (roy.bates for those that are on AmiBay as well).
Basically he pointed that the "+5v RGB ON signal" that is used in scart RGB cable schematics is the TTL-SYNC output from the motherboard which is not meant to be used like that and causes image quality degradation especially on LCD panels (at least my LG sets did not like that much, had issues from ghosting to pixel crawling).


So this switch just selects what PIN1 on the RGB port is: either stock TTL-Sync for use with Amstrad monitors or +5v via a resistor so you get correct RGB Switching voltage at a scart plug. After I did this all my image quality issues went away.


Now I must also mod the TTL-LUMA signal at the scart plug, I believe it will be better if I use a 680ohm resistor in series which along the internal 75ohm termination of monitors it will result in a better/more-standard signal.


Ofcourse if anyone has a better idea please share - the machine came with the b/w monitor and TBH this went to storage as I will be using the 6128+ most of the time with a 1084 or a rgb-capable tv set in case I remove it from my desk.


Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 10:43, 22 June 16
Very neat work there. I like the plastic strip you added under the drive. The RGB switch is a cool idea too. Haven't seen that done before.

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 11:23, 22 June 16
Thanks Bryce!
Credits for the 5v/ttl_sync idea should go to roy.bates though, it was his idea  8)


The plastic profile under the drive was indeed a success, if you look at the other pics there are actually 2 profiles that are screwed under the drive and the whole assembly is hotglued on the bottom shell part.
The plastic profiles are measured in height so that the drive also tops under the upper shell, meaning there is no space for it to move upwards after the case is closed. It's really solid once closed.


The only thing I don't like at the whole deal is a part at the floppy head switch filling, you can see it's not even on top... luckily you can't really see it in real life , the photos do enhance it though  ::)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: Bryce on 11:29, 22 June 16
I'll congratulate Roy then, next time I'm talking to him :D

Bryce.
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: ||C|-|E|| on 12:13, 22 June 16
All very neat, as Bryce said, and useful!! I really like how it is done. On the other hand, this is the first time I see the video mod as well, very nice indeed  :)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 12:33, 22 June 16
Yes it was a nice idea, it does solve issues with lcd panels as they are mostly more sensitive than crt ones. But even on a crt panel having a ttl signal acting up as voltage is not that great either - sure it works but it's kinda wrong (unless ofcourse you have something like the 1084 were rgb switching voltage is not needed at all)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: ||C|-|E|| on 14:36, 22 June 16
It would be very nice to properly document the mod in the wiki  :)
Title: Re: Accidentally used a 9v PSU on the 6128 plus, what's the damage?
Post by: keropi on 17:18, 22 June 16
Maybe these pics help so others can understand it?

The main point here is to control what goes to SCART pin16 (it is the RGB enable pin and if it is in the 1~3v range then the monitor gets the signal that a RGB source is connected) . So we need SCART pin16 to have a correct voltage for this plus we want to it to be "real" voltage and not a TLL signal that can carry with it other information that mess up with the monitor.


For this purpose we need to install a Single Pole Double Throw (SPDT) switch, so we control what goes to pin1 of the 6128 PLUS.
- we need to lift R87 from one side just like in the pics below (resistor end is the stock TTL Sync signal and the motherboard via that is now not-connected goes straight to pin1 of the RGB port)
- find a good 5v point nearby to get our RGB enable voltage via a 150ohm resistor to bring it around ~1.7v so that it is within specs.


Here are a couple of pics with the points that I used, I hope they are self-explanatory:


(http://i.imgur.com/z9PNvvM.jpg) (http://imgur.com/z9PNvvM)


(http://i.imgur.com/uCxiDvn.jpg) (http://imgur.com/uCxiDvn)