:'(
I knew it was going to happen one day... and this was NOT caused by LambdaSpeak hardware development.
I simply confused 4.5 V position on my PSU with the 12 V position... that didn't go to well with my 464 :-[
It still powers up, but shows gray screen. See screenshots attached. Any ideas, what's the most likely component that I fried? So stupid... well I still have some other CPCs, but that was my favorite :-[ Please help me fix it.
Thanks, friends!
Candidate number one is the RAM. If you are really lucky one of the RAMs shorted and stopped the 12V from damaging anything else.
Bryce.
Quote from: Bryce on 08:36, 06 December 17Candidate number one is the RAM.
Thanks Bryce.
Is there a straight forward way to figure out which RAM chips got burned, using logic probe or similar?
Also, can I just use the RAM from another CPC, are they all compatible? (Same question I would have
about different Gate Array / ASIC / ... versions - all plug and play and 100% pin compatible?)
Quote from: LambdaMikel on 16:48, 06 December 17
Is there a straight forward way to figure out which RAM chips got burned, using logic probe or similar?
Usually when a RAM chip is dead, it tends to heat up, way more than the good ones.
Give 5v to the motherboard and take temp readings of the chips.
You might be able to tell just by touch.
Quote from: LambdaMikel on 16:48, 06 December 17Same question I would have about different Gate Array / ASIC / ... versions - all plug and play and 100% pin compatible?)
Seems the answer is no:
http://www.cpcwiki.eu/index.php/Gate_Array_and_ASIC_Pin-Outs
Looking at my board, it seems it has support for 40010 and the older 40007 and 40008!
Has anybody tried swapping another Gate Array into the empty extra socket before?
I am asking because I still have another 40007 / 40008, but no 40010 for Gate Array testing.
Have a look here
Gerald Ram Test ROM
Quick and dirty RAM test for CPC (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/quick-and-dirty-ram-test-for-cpc)
Ray
Great, thanks for the link the MEMTEST.bin
Now I only have to figure out how to burn a lower ROM with my XMem.
Btw, the RAM chips indeed all get quite hot.
Can someone give me hint how to install RamTest.bin please? I have an XMem. I am using "exrom.bas" from XMem tools disk A, and then it shows that ROM 0 = 64, ROM 1 = 01, and LOWER ID = 71. So after "filename? " I loaded ramtest.bin, and tried all 3 IDs, but when I booted in XMem boot mode, I either got a pixelated screen or colorful vertical stripes. What am I doing wrong? I am using a 6128. After that, I have to run "setup" from XMem tools disk again, in order to get the XMem Firmware 3.14 back again, so it seems to be replacing some system roms, but it doesn't work.
Quote from: LambdaMikel on 06:47, 07 December 17
Can someone give me hint how to install RamTest.bin please? I have an XMem. I am using "exrom.bas" from XMem tools disk A, and then it shows that ROM 0 = 64, ROM 1 = 01, and LOWER ID = 71. So after "filename? " I loaded ramtest.bin, and tried all 3 IDs, but when I booted in XMem boot mode, I either got a pixelated screen or colorful vertical stripes. What am I doing wrong? I am using a 6128. After that, I have to run "setup" from XMem tools disk again, in order to get the XMem Firmware 3.14 back again, so it seems to be replacing some system roms, but it doesn't work.
Flasher from the disc can do it. Program the required lower rom into slot 7. The xmem does not remap slot 7 as only a small number of cpc 6128 machines can support it. So the xmem uses slot 7 for the lower rom.
Sent from my ONEPLUS 3t using Tapatalk
Thanks guys. OK, so I tried |flash,"ramtest.bin",71 (= &47) and after that, when I boot the 6128 from XMem
Boot, I am getting pixelated screen.
OK, figured it out by now... it was my DSK / HFE image creation process which was bad.
Was able to flash and run it now - thanks to all who helped!
Unfortunately, I am seeing a lot of red... probably not a good sign, uhh? (http://www.cpcwiki.eu/forum/Smileys/SoLoSMiLeYS1/lipsrsealed.gif) (http://www.cpcwiki.eu/forum/Smileys/SoLoSMiLeYS1/embarrassed.gif%20%5Bimg%20alt=:'(%5Dhttp://www.cpcwiki.eu/forum/Smileys/SoLoSMiLeYS1/cry.gif) (http://www.cpcwiki.eu/forum/Smileys/SoLoSMiLeYS1/doh.gif)
I think from this we can assume that I burned ALL my RAM chips?? :o >:( :laugh:
No Not yet
Just replace 1 (One) Ram Chip and re run the RamTest.
Good luck
Ray
It could be a good time to install socketed RAM though :D . I mean, Bryce always says that if it is not broken don´t fix it, and it could be that only one chip is damaged. However, nothing stops you now from removing all of them and install new ones. Even if only one chip is not OK, you will probably heat all the others by removing and reinstalling it and since you have the board outside and so on... ;D
P.D: besides, a board with only one socketed RAM chip does not look nice! :laugh:
I do agree.
While you are at it, socketing the ram chips will make your life a lot easier while trying to find the faulty ones.
Quote from: ||C|-|E|| on 13:43, 08 December 17However, nothing stops you now from removing all of them and install new ones.
Only my extremely bad desoldering skills. I am ok soldering, but never figured out how to desolder properly. I already damaged 2 trace trying to remove the first RAM chips... I am afraid I won't have enough time to do this (took me 2 hours for one chip - family is getting mad) :'(
If you're desoldering a bad through-hole IC, don't even bother trying to take it out in one piece. Use sidecutters to cut all the pins, then you can remove each pin individually.
Thanks Pelrun, thats a great suggestion.
To desolder, what I like to do is to use quite a lot of braid and flux :) . Before cutting the pins of the ICs, I remove as much solder as I can with the braid and then I proceed to cut. This is good because it prevents tensions on the board that otherwise can appear when cutting. Once the IC is completely gone, I take the pins, one by one, with a pair of pliers. You grab the pin, heat it a little bit with the iron and it is dead easy to remove it. Having the proper cutter it is very important too. Actually, if the tool is very good, you can cut the pins without removing the solder first, but I prefer to do it anyway.
I removed the IC from this 6128 board using the technique above and, as you can see, it looks nice and clean :)
(https://c1.staticflickr.com/3/2867/33690767731_88b142602a_o.jpg)
Quote from: ||C|-|E|| on 23:58, 08 December 17Once the IC is completely gone, I take the pins, one by one, with a pair of pliers.
Thanks, that is a good technique - I used tweezers, and it worked pretty well. The remaining pin fragments from the ICs I was able to push through by heating the solder point and pushing some wire through, such that I could pick it then up from the other side. Thanks for suggesting it. All solder points are empty now.
Now I need to remove more solder because the holes are still blocked by solder. Desoldering braid is difficult to handle, too, IMHO. Maybe I have the wrong iron for that kind of work... I have this pump, but frequently it doesn't suck up all the solder. Just enough for the hole to remain to be blocked :-X
I guess before putting in sockets I will also need to figure out how to reconnect the two brocken tracks / traces.
Btw, the 40010 Gate Array didn't get damaged - I tested it in a 6128. No problems.
Quote from: LambdaMikel on 07:19, 11 December 17
I guess before putting in sockets I will also need to figure out how to reconnect the two brocken tracks / traces.
Hi MikeI just run a length of wire wrap (Kynar Wire .025mm 30AWG) or equivalent (Solid Insulated wire).From the pin on the socket back to where the Track (Trace) starts , Please don't try and fix the Track (Trace)Good luckRay
Quote from: LambdaMikel on 07:19, 11 December 17
Thanks, that is a good technique - I used tweezers, and it worked pretty well. The remaining pin fragments from the ICs I was able to push through by heating the solder point and pushing some wire through, such that I could pick it then up from the other side. Thanks for suggesting it. All solder points are empty now.
Now I need to remove more solder because the holes are still blocked by solder. Desoldering braid is difficult to handle, too, IMHO. Maybe I have the wrong iron for that kind of work... I have this pump, but frequently it doesn't suck up all the solder. Just enough for the hole to remain to be blocked :-X
I guess before putting in sockets I will also need to figure out how to reconnect the two brocken tracks / traces.
Btw, the 40010 Gate Array didn't get damaged - I tested it in a 6128. No problems.
If you cut the pins at the right point you don't need to poke the pins out with wire. I did a tutorial (with pictures) here of how to do it: http://www.cpcwiki.eu/index.php/IC_Repair
Bryce.
Quote from: Bryce on 08:46, 11 December 17If you cut the pins at the right point you don't need to poke the pins out with wire. I did a tutorial (with pictures) here of how to do it: http://www.cpcwiki.eu/index.php/IC_Repair (http://www.cpcwiki.eu/index.php/IC_Repair)
Very useful tutorial! Yes, I didn't have these very fine cutters, so I couldn't get too close to the pins somehow. Need to get better equipment for that kind of job.
Has anyone ever tried compressed air to blow out the solder from the holes? This is really the hardest part of the job I think.
Bryce, what kind of iron are you using for the wick. It never seems to be doing a lot for me. Maybe the tip of my iron is to fine, or it doesn't have enough watts?
Not sure what desolder wick/braid you are using, but the difference between good and bad is night and day.
Or more importantly, the difference between removing solder really easily, or actually destroying a board...and I am not exaggerating.
I once purchased some cheap Chinese braid, that you could probably call a clone as the labeling looked similar to a brand name one.
It was simply unusable, and if I had persisted, would have started destroying things.
My brand of choice is Goot Wick. I actually, swear by it.
I just recently removed all eight RAM chips in an Atari 800XL with this alone and it took me roughly an hour and a half.
And that was non destructively removing the chips, in the end I re-used seven of the eight as only one was dead.
I even have a cheap desolder station that works well, but for me, the wick is my go too.
Cheers,
Shane
Quote from: LambdaMikel on 16:53, 11 December 17
Very useful tutorial! Yes, I didn't have these very fine cutters, so I couldn't get too close to the pins somehow. Need to get better equipment for that kind of job.
Has anyone ever tried compressed air to blow out the solder from the holes? This is really the hardest part of the job I think.
Bryce, what kind of iron are you using for the wick. It never seems to be doing a lot for me. Maybe the tip of my iron is to fine, or it doesn't have enough watts?
Huuuum... that solder should definitely go just with braid and enough flux. I tend to use this one:
https://www.ebay.co.uk/itm/15m-Reel-of-2mm-Chem-Wik-Solder-Remover-Wick-Mop-Desoldering-Braid/272289238812?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 (https://www.ebay.co.uk/itm/15m-Reel-of-2mm-Chem-Wik-Solder-Remover-Wick-Mop-Desoldering-Braid/272289238812?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649)
with flux similar to this:
http://www.ebay.co.uk/itm/New-flux-soldering-paste-in-the-20g-tin-for-electronics-SMD-plumbing-DIY-etc/253018379203?epid=2255531445&hash=item3ae91213c3:g:Bk8AAOSwIVhaKCtC (http://www.ebay.co.uk/itm/New-flux-soldering-paste-in-the-20g-tin-for-electronics-SMD-plumbing-DIY-etc/253018379203?epid=2255531445&hash=item3ae91213c3:g:Bk8AAOSwIVhaKCtC)
What I do is to impregnate the braid with the flux, then I put it on top of the hole with the solder and then I heat it until all the solder goes into the braid by capillarity. In very rare cases, it may be necessary to add a little bit more of fresh solder to help the process, but this is not common. Then, as Bryce said, if you cut the pins close to the IC, it is very easy to take them off with a couple of pliers :) .
However, I would say that the way I do it is pretty old fashion. Nowadays you have this odorless liquid flux that works very well and it is not messy, like the one I use. Actually, I always need to clean all my boards afterwards with isopropanol. I just keep working with it because I have tons and I feel really at home with the stuff :) .
Regarding the iron, I would definitely go for a soldering station. You can buy reasonably cheap ones that do the job very well and will allow you to avoid overheating the board. I bought an Atten from RS components and I am really happy with it. It is nothing special, but more than enough for my needs, and it was less that 50 pounds :)
P.D: for the traces, Audronic advice is very good, you can just use a very thin cable and it will do the trick. The picture shows an AMX mouse that had a bad track and I just bridged the two positions with that little yellow wire. You could try something like that.
(http://www.cpcwiki.eu/forum/index.php?action=dlattach;topic=12129.0;attach=19845;image)
Hi LambdaMikel, I had to do exactly the same process as you in a non working cpc, the same "grey screen of death" and finally I repaired it and came to life after changing the ram and, as strange as it sounds, a resistor which was in the way of the INT signal from the 40010 IC... read here: http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/grey-screen-of-death-(revisited)/ (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/grey-screen-of-death-(revisited)/) and here (in greek, but you can google translate) http://underground.iamretro.gr/index.php?threads/%CE%95%CF%80%CE%B9%CF%83%CE%BA%CE%B5%CF%85%CE%AE-amstrad-6128-%CE%BC%CE%B5-%CE%BA%CE%B1%CE%BC%CE%BC%CE%AD%CE%BD%CE%B5%CF%82-%CE%BC%CE%BD%CE%AE%CE%BC%CE%B5%CF%82.8555/ (http://underground.iamretro.gr/index.php?threads/%CE%95%CF%80%CE%B9%CF%83%CE%BA%CE%B5%CF%85%CE%AE-amstrad-6128-%CE%BC%CE%B5-%CE%BA%CE%B1%CE%BC%CE%BC%CE%AD%CE%BD%CE%B5%CF%82-%CE%BC%CE%BD%CE%AE%CE%BC%CE%B5%CF%82.8555/)
Of course you should put dip sockets, because it will be easier in the future to replace damaged ram chips, I did it in that way, and it's also better for testing the ram.
I have an iron with 25 watts, and it was hard to desolder, it took me two days to achieve it, and in the process I broke some tracks which I had to patch with small cables. A trick is to hot the board with some heat air pistol or a dryer for the hair, and the apply the iron, it will be more easy.
So, review your tracks with a multimeter in order to check continuity. I recommend you to find an amstrad service manual in order to detect where the problems with tracks could be.
Good luck!
Quote from: LambdaMikel on 16:53, 11 December 17
Very useful tutorial! Yes, I didn't have these very fine cutters, so I couldn't get too close to the pins somehow. Need to get better equipment for that kind of job.
Has anyone ever tried compressed air to blow out the solder from the holes? This is really the hardest part of the job I think.
Bryce, what kind of iron are you using for the wick. It never seems to be doing a lot for me. Maybe the tip of my iron is to fine, or it doesn't have enough watts?
I use an Ersa iCon Nano with a chisel tip for most work. Usually set around 360°C. Definitely only use branded braid, the cheap shit usually doesn't contain enough flux (if any). Also, buy yourself a flux pen to add more where required.
The old solder will be very dry and, as the PCB was wave soldered, it will contain zero flux. So although it may sound counter-productive, add some new solder to each hole before you try removing the solder with braid.
Bryce.
I've been using a cheap desoldering iron:
(https://i.ebayimg.com/images/g/qbQAAOSwhQhYz2lf/s-l500.jpg)
https://www.ebay.co.uk/itm/30W-220V-50Hz-Electric-Vacuum-Solder-Sucker-Desoldering-Pump-Iron-Gun-E-Class-/172584401671
For $30, it makes removing through hole chips ridiculously easy. You just have to be careful when releasing the red button, as it spits out everything it sucked (so point it away from your board!)
But you've no idea of how hot it is, so it could be destroying parts or even the PCB!
Bryce.
I have no idea how hot my regular iron is either ¯\_(ツ)_/¯
You raise a valid concern, but these things tend to be not hot enough instead of way too hot.
I've damaged a pcb before, trying to remove a chip with a simple soldering iron. The thing was stubborn and I was new to soldering, I ended up breaking some of the pads when yanking it. With this desoldering tool, I haven't had a single problem. Put it over the stub, press the button and do a circular movement to detach the pin, and done. Sometimes I use a pair of tweezers and shake the pin back and forth to snap it from the hole if its still attached.
For freeing the pins from the solder in the hole you can get these: https://www.ebay.de/itm/8PCS-Lots-Hollow-needles-desoldering-tool-electronic-components-Stainless-steel/172280051221 (https://www.ebay.de/itm/8PCS-Lots-Hollow-needles-desoldering-tool-electronic-components-Stainless-steel/172280051221?hash=item281cb0f615:g:WFoAAOSwMsVXjdVl)
You just push the hollow point over the end of the pin and into the hole. Much safer than shaking the pin with a tweezers.
Bryce.
Oh, very nice! I like that.
Quote from: Bryce on 15:00, 12 December 17
For freeing the pins from the solder in the hole you can get these: https://www.ebay.de/itm/8PCS-Lots-Hollow-needles-desoldering-tool-electronic-components-Stainless-steel/172280051221 (https://www.ebay.de/itm/8PCS-Lots-Hollow-needles-desoldering-tool-electronic-components-Stainless-steel/172280051221?hash=item281cb0f615:g:WFoAAOSwMsVXjdVl)
Exactly what I was looking for! Will order a pair these... much better than the wire I used (and the leads of some components, such as resistors).
I finally have sockets in the board. I used a can of compressed air to blow out the solder from the holes. I guess I really need a better iron or better desoldering wick. And then, who on earth designed this board??? The spacing / pitch of the RAM ICs doesn't fit the IC sockets! I had to bend the IC socket pins - the width didn't match! For that reason, I also couldn't use the standard spring-loaded IC sockets, but had to use the round ones. The spring-loaded ones would just pop out of the socket while I was trying to bend the pins to make it match and push them in.... what a nightmare.
Quote from: pabloingreece on 06:39, 12 December 17
Hi LambdaMikel, I had to do exactly the same process as you in a non working cpc, the same "grey screen of death" and finally I repaired it and came to life after changing the ram and, as strange as it sounds, a resistor which was in the way of the INT signal from the 40010 IC... read here:
Thank you Pablo, that is good information, very useful!
I did the memtest.bin again with all RAM ICs removed by now, and I would have expected an all red screen. It still shows some weird patterns after the border changes, so maybe some other components are damaged as well. I will know soon - my RAM should arrive in 2 days.
Btw, does anybody know what the screen of memtest.bin should look like with all RAM chips removed, and all other chips being fine?
Another concern I have - I accedentially heated some ceramic capacitors quite a bit during the unsoldering process... are they going bad easily from that?
Quote from: khaz on 13:46, 12 December 17I've been using a cheap desoldering iron:
Wow! Quite a weapon! Hopefully I will never have to go through such an extensive desoldering job again, but if, I will consider using this tool.
Quote from: LambdaMikel on 18:11, 12 December 17
Thank you Pablo, that is good information, very useful!
I did the memtest.bin again with all RAM ICs removed by now, and I would have expected an all red screen. It still shows some weird patterns after the border changes, so maybe some other components are damaged as well. I will know soon - my RAM should arrive in 2 days.
Btw, does anybody know what the screen of memtest.bin should look like with all RAM chips removed, and all other chips being fine?
Another concern I have - I accedentially heated some ceramic capacitors quite a bit during the unsoldering process... are they going bad easily from that?
I think the test is only for testing with ram connected, if you don't have any ram, I don't think it tests any other component in the board.
In my case, I think the ram stopped the overvoltage to go further, because all the other components were fine, also the fried resistor could have acted as protection. So wait for the ram chips, check track continuity and check then if the ram test is ok.
If this does not resolve the problem, then will see.
Quote from: LambdaMikel on 18:11, 12 December 17
I did the memtest.bin again with all RAM ICs removed by now, and I would have expected an all red screen. It still shows some weird patterns after the border changes, so maybe some other components are damaged as well. I will know soon - my RAM should arrive in 2 days.
Btw, does anybody know what the screen of memtest.bin should look like with all RAM chips removed, and all other chips being fine?
I've just tested that and what you see is expected. RED mean all bit a read at 1, which is expected for floating TTL bus. The moving pattern is a effect of the floating bus and other activity.
The pattern changes after the border change are linked to the Z80 activity.
If all RAM is good the screen should be black. The memory is cleared by the last test pass.
Quote from: LambdaMikel on 18:11, 12 December 17
Another concern I have - I accedentially heated some ceramic capacitors quite a bit during the unsoldering process... are they going bad easily from that?
That should not be a problem.
Quote from: gerald on 20:34, 12 December 17I've just tested that and what you see is expected. RED mean all bit a read at 1, which is expected for floating TTL bus. The moving pattern is a effect of the floating bus and other activity. The pattern changes after the border change are linked to the Z80 activity.
That is good to know! This gives me hope that by replacing the RAM the CPC can be fixed. Thanks for this test, Gerald!
My RAM arrived today. I also tried to fix the traces. It got better for sure, but still some errors. Is it possible to tell what the remaining problem is? I checked all PINs of the RAM ICs with the logic probe if they receive pulses while RAMTEST is running, they are all active by now, after having fixed the tracks. Maybe the patch cables are too long?
Oh, I forgot one defect track... now the screen grizzle is gone, but the border still shows a red bar.
What could that be, what does it mean?
Mark the Ram chips.
Move 4 up to new position, replace the 4 that were moved from the old position.
and see if the Red bar (s) has changed position
Good luck Ray
Welcome back, beloved 464 ;D
Sorry I did that to you... I did such a poor job desoldering. But good learning experience.
Happy I was able to resurrect it.
Thanks to all who helped, you guys rock!!! 8) ;D
Ok thats good.
? what was finally wrong ?
Thanks Ray
Quote from: Audronic on 08:40, 15 December 17
? what was finally wrong ?
I replaced all the RAM chips, socketed them. I don't know which individual RAMs were bad, I suppose all, according to MEMTEST.
Then, there were more traces disconnected than I thought, caused by crude desoldering. I had made highres pictures of the traces before I put the sockets in; I inspected them, and that way I found the first bad tracks.
But then some disconnected traces weren't very visible. I finally looked at the PINOUT for the 4164 RAM chips and figured that A0 - A7 should be connected identically to all 8 chips, so I tested continuity with my multimeter between all pairs of corresponding data bus pins, and figured out that a couple more connections were broken -> more wires. Finally, everything was green in RAMTEST.
So it was really the combination of understanding the pinout of the 4164 and the continuity tests that enabled me to fix the problem.
Look at it, working again :) Congratulations! :D
Quote from: ||C|-|E|| on 22:08, 15 December 17Look at it, working again :) Congratulations! :D
Thanks :)
Great news! as I told you, I had te same problem, same broken tracks. I reviewed the schematics of the service manual and before removing I made some photos. So, I understand completely the awesome feeling of bringing back to life the old friend of us, the cpc.
Good job!