Hi,
here is my problem, i hope someone will be able to help me.
I have a Qwerty CPC6128 which has "Keyboard" problems, in fact i think it isn't a keyboard problem.
When I hit the DEL key for example, it makes a lot of strange characters on the screen, other keys are OK.
And when i use a joystick i don't have the Arrow characters, but strange characters instead.
I changed the Z80, I change the keyboard to see if it was related.
Every thing else is working great : Disc, Parados, Megaflash when connected.
Any clues ? :'(
Can you swap the ay? I had a similar issue once, and a new ay fixed it.
Dodgy Firmware ROM?
Bryce.
Quote from: CraigsBar on 16:11, 21 October 14Can you swap the ay? I had a similar issue once, and a new ay fixed it.
Ok, i will try tomorrow with a new AY (if i have one...)
Quote from: Bryce on 16:11, 21 October 14
Dodgy Firmware ROM?
Bryce.
I will try also ;-) , i must have a Parados Eprom somewhere ::)
It's very unlikely to be the AY, no AY failure could cause those effects. Only try a different AY if it's already socketed. It's also more likely to be the Firmware/BASIC ROM, not the AmsDOS (where ParaDOS goes).
Bryce.
Ok,
i'm going to desolder the Basic ROM first just to try a "good" one !
Thank you again :)
If it isn't the ROM or the AY, then it could be the PIO8255.
Good luck!
Well in order :
The basic, the AY and then the PIO
Got a lot of work ;-)
Thank you
Yes, but later you got a socket for all of them! And that's awesome! 8)
Quote from: TFM on 17:12, 23 October 14
Yes, but later you got a socket for all of them! And that's awesome! 8)
Yes, but it also means that you have destroyed perfectly good hard to get parts if you just blindly swap them all.
Bryce.
Quote from: Bryce on 18:35, 23 October 14
Yes, but it also means that you have destroyed perfectly good hard to get parts if you just blindly swap them all.
Bryce.
He only swaps the broken parts.[nb]Or the parts having been suggested here.[/nb]
Quote from: TFM on 19:57, 23 October 14
He only swaps the broken parts.[nb]Or the parts having been suggested here.[/nb]
Not all the parts suggested here are broken. The AY is very unlikely to be broken.
Bryce.
Well, we will see at the end... we could actually do some bets ;)
I guess the AY has a bigger chance to be broken than the PIO. Also if the Basic-ROM would be broken, you would rater get random effects or just altered keys, but the way he describes it the problem is located in key scanning, in particular the AY reports a bunch of keys not pressed.
One quid on the AY ;)
He says the DEL key produces "lots of characters". Any AY problem can give you wrong or no character, but no AY failure would cause lots of characters to appear. You get two characters if an AY internal pull-up resistor fails, but it still gives the correct character first. Even if they all failed, I don't think it would cause that and it would effect all keys the same.
Bryce.
Dirty keyboard membrane or failing membrane contact to the motherboard, maybe?
Quote from: robcfg on 14:41, 24 October 14
Dirty keyboard membrane or failing membrane contact to the motherboard, maybe?
That still wouldn't cause multiple strange characters to appear.
Bryce.
My friend once repaired 464 and 6128 which had problems with kays with bigger numbers than 70. Sequences of characters on screen in each of them were different, but, after changed AY problem disappeared.
He said that it looks like AY had a gates that PIO uses to operate the keyboard and joystick. But such AY which making problem in CPC still playing well in sound cards for ZX Spectrum.
I guess cause was test connecting something strange to joystick port.
Quote from: Bryce on 21:12, 23 October 14
He says the DEL key produces "lots of characters". Any AY problem can give you wrong or no character, but no AY failure would cause lots of characters to appear. You get two characters if an AY internal pull-up resistor fails, but it still gives the correct character first. Even if they all failed, I don't think it would cause that and it would effect all keys the same.
Bryce.
I bet you a beer it's the AY! Because if it fails, it can start delivering random bits so you get lots of characters when pressing one key. ;)
Quote from: robcfg on 14:41, 24 October 14Dirty keyboard membrane or failing membrane contact to the motherboard, maybe?
He exchanged the keyboard already. :)
yes i tested the keyboard, so it is not that.I just removed the 40025 today, so i will solder the socket tomorrow and test it 8) First answer tomorrow 8) Who will win ? ;D
My best wishes! Hope it will work again soon!
Hi Talrek,
just fixing a CPC+ at the moment and it has a similar problem to what you describe. Is this the series of characters you get when you press DEL? If so, changing the AY doesn't solve the problem, nor does changing the ROMs. Unfortunately, this is a plus, so it doesn't have a 8255 PIO, but I'll let you know as soon as I've found the issue...
Bryce.
:laugh: I was just going to reply that i changed the Basic and AY and it doesn't work :laugh: :laugh:
All this work for "almost" nothing (in fact i have the luck to have now a CPC with two more sockets ;D [size=78%])[/size]
Then i saw your message : it is EXACTLY the same characters when i hit the DEL key.
Do you want that i try to change the 8255 PIO (even if i think it isn't the cause...) ??
Quote from: Bryce on 14:39, 25 October 14
Hi Talrek,
just fixing a CPC+ at the moment and it has a similar problem to what you describe. Is this the series of characters you get when you press DEL? If so, changing the AY doesn't solve the problem, nor does changing the ROMs. Unfortunately, this is a plus, so it doesn't have a 8255 PIO, but I'll let you know as soon as I've found the issue...
Bryce.
If that was one of the boards I sent you then it looks like the AY swap did not fix it for me 7 years ago and my memory is failing :(
Sorry.
Quote from: talrek on 17:43, 25 October 14
:laugh: I was just going to reply that i changed the Basic and AY and it doesn't work :laugh: :laugh:
All this work for "almost" nothing (in fact i have the luck to have now a CPC with two more sockets ;D [size=78%])[/size]
Then i saw your message : it is EXACTLY the same characters when i hit the DEL key.
Do you want that i try to change the 8255 PIO (even if i think it isn't the cause...) ??
Ok, so we have exactly the same issue, good to know. The plus doesn't have a PIO, so that's not going to be the issue. However, I have noticed that this PCB also has problems with the floppy drive, does yours too? Also one other thing that I noticed. Mine has a French keyboard and an English ROM, what about yours?
Hopefully I can check it some more today and maybe find the solution.
Bryce.
Bit 7 or D7 is stuck. All these keys are on the same bit but over multiple keyboard columns. Is there a short somewhere between keyboard and ay?
Just had a thought. If a test program was designed to be run from |cpm then you could force a link on the board to boot com when cpc starts, that may make it possible to run some keyboard tests.
A better test program would run from Rom, but that needs extra hardware to start it putting it out of the reach of many.
Quote from: arnoldemu on 11:28, 26 October 14
Bit 7 or D7 is stuck. All these keys are on the same bit but over multiple keyboard columns. Is there a short somewhere between keyboard and ay?
Yes, that's what I thought too, but I can't find the spot where it's happening.
Bryce.
Quote from: Bryce on 12:55, 26 October 14
Yes, that's what I thought too, but I can't find the spot where it's happening.
Bryce.
I have attached a dsk I made.
If /exp is setup so disc rom is 0, the cpc will autoboot from this when started up. No idea if the plus will auto start I never tested it.
The display will show lines. Red blobs will appear when a key is pressed.
Without any keys pressed it should just be vertical lines. If keys are pressed, or held by the hardware red blobs will appear.
From left to right are the bits with a line, with the lines going down the screen.
Bit 7 on the left and bit 0 on the right.
From this it should be possible to work it out a bit more easily.
Quote from: Bryce on 10:51, 26 October 14
Ok, so we have exactly the same issue, good to know. The plus doesn't have a PIO, so that's not going to be the issue. However, I have noticed that this PCB also has problems with the floppy drive, does yours too? Also one other thing that I noticed. Mine has a French keyboard and an English ROM, what about yours?
Hopefully I can check it some more today and maybe find the solution.
Bryce.
English keyboard and ROM for me.
No problem with External Floppy drive.
With the joystick i have multiples characters before the arrows :
Thanks, Talrek can try this, but unfortunately the floppy drive is dead on my PCB too, so I'd need to fix that first. I'll continue the manual search first.
Bryce.
Quote from: Bryce on 13:29, 26 October 14
Thanks, Talrek can try this, but unfortunately the floppy drive is dead on my PCB too, so I'd need to fix that first. I'll continue the manual search first.
Bryce.
If I create a cart version would that help?
Eventually I could extend it to detect and pin point the problem, and add other testing to diagnose other problems.
It would be excellent, but no need anymore, I've found the problem. Here's what's normally on each scan pin (coming from the ASIC in my case):
[attach=2]
And here's what's on pin 1 of CP104 (ie: pin 80 of the ASIC):
[attach=3]
As you can see, the signal is inverted (or not being inverted to be exact), which is causing the mess. On Talreks CPC I suspect IC101 (74LS145) has failed, as it is responsible for these signals on a classic CPC. In my case the ASIC seems to have dropped an inversion stage :( All is not lost however, I'll cut the trace and add an external inverter and see if that can solve the internal failure.
Bryce.
Edit: Hmmm, looks like this is an ex-CPC. I added an inverter and it was still causing problems. Then I connected all pins up to my Logic analyser to see what's happening. Although the signal is now correctly inverted, the pulse is about 4 times longer than it should be and also not at the correct time. This isn't something that can be easily fixed externally, so we have a dead ASIC. Time to look at the second plus that Craig sent me. It has a questionable ABBA mod that needs to be removed and it currently boots to a blue border with yellow box, so RAM is the first suspect.
wooooowwww :o :o :o
Ok if you say so.... i will try a good one so..
I keep in touch :)
Quote from: talrek on 15:47, 26 October 14
wooooowwww :o :o :o
Ok if you say so.... i will try a good one so..
I keep in touch :)
I would be interested to see the result from my programming because then i could detect this in code and tell somebody to try that chip first.
Unfortunately my PCB wasn't in a state to read disks, but Talrek could still test it on his CPC. If not, it's relatively easy to simulate this failure, so I can test it later if Talrek doesn't.
Bryce.
Quote from: Bryce on 14:35, 26 October 14
It would be excellent, but no need anymore, I've found the problem. Here's what's normally on each scan pin (coming from the ASIC in my case):
[attach=2]
And here's what's on pin 1 of CP104 (ie: pin 80 of the ASIC):
[attach=3]
As you can see, the signal is inverted (or not being inverted to be exact), which is causing the mess. On Talreks CPC I suspect IC101 (74LS145) has failed, as it is responsible for these signals on a classic CPC. In my case the ASIC seems to have dropped an inversion stage :( All is not lost however, I'll cut the trace and add an external inverter and see if that can solve the internal failure.
Bryce.
Edit: Hmmm, looks like this is an ex-CPC. I added an inverter and it was still causing problems. Then I connected all pins up to my Logic analyser to see what's happening. Although the signal is now correctly inverted, the pulse is about 4 times longer than it should be and also not at the correct time. This isn't something that can be easily fixed externally, so we have a dead ASIC. Time to look at the second plus that Craig sent me. It has a questionable ABBA mod that needs to be removed and it currently boots to a blue border with yellow box, so RAM is the first suspect.
Oh Shambles!!
Sorry :( Is the 2nd one the one that originally had an STS Copymod on it? I don't remember either of those actually having an ABBA switch?
Craig
Quote from: Bryce on 16:04, 26 October 14
Unfortunately my PCB wasn't in a state to read disks, but Talrek could still test it on his CPC. If not, it's relatively easy to simulate this failure, so I can test it later if Talrek doesn't.
Bryce.
I think I could simulate it too. I am guessing that you can press any key, and when you do the result is replicated across all keyboard lines. So that pressing a joystick direction will give a different set of keys than delete, but this assumes nothing shows until you press a key.
An alternative is a key always appears stuck because an input always stays low, so both could be tested for.
I think if the membrane failed you could see all keys in a column be unresponsive, or more than one if it is a partial failure.
Quote from: CraigsBar on 16:04, 26 October 14
Oh Shambles!!
Sorry :( Is the 2nd one the one that originally had an STS Copymod on it? I don't remember either of those actually having an ABBA switch?
Craig
CPC Laptop. (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/cpc-laptop/msg88077/#msg88077)
:)
The socond one had a chip piggybacked onto the 74HC14, some tracks cut and wires hanging from the floppy port..... and now works :)
Bryce.
IT WORKS !!!!!!!!!!!!!!
8) 8) 8) 8) 8) 8) 8)
It was the problem... damn IC :laugh:
So, i'm sorry i am not able to test your disk as the CPC works now :-[
Result! Congrats.
@TFM (http://www.cpcwiki.eu/forum/index.php?action=profile;u=179): Guinness or Reissdorf Kölsch please :D
Bryce.
Yes really thank you !!!
If you come by France near Bordeaux i would offer you a beer :D
Marking solved!
Quote from: Bryce on 17:36, 26 October 14
Result! Congrats.
@TFM (http://www.cpcwiki.eu/forum/index.php?action=profile;u=179): Guinness or Reissdorf Kölsch please :D
Bryce.
Ok, Guinnes ready for pick up. However it wasn't the BASIC ROM either ;) Happy to see that the problem is solved. :)
hi All,
I bought a 6128+ just recently on ebay, and although it was advertised as working it has the exact same (observed) problem described here as per the image in reply#20. I have 2 6128+ machines and I have swapped keyboards and they both show the same problem on the faulty 6128+ but both work perfectly on the good 6128+. On the faulty one however I found out that the guy who sold it to me modified the 6128+ to use a different PSU plug which is another annoying thing (that wasn't advertised). Whether he did or not, one of the smaller chips has an extra wire wired to it on this 6128+ also.
Any queues as to what I should look at to isolate and fix this problem?
Thanks, Julian
Unfortunately, this probably means that the ASIC is faulty and this isn't a part that you can get, other than removing one from another Plus. Which is kind of pointless. That's an ex-Plus you have there.
Sorry,
Bryce.
I guess that sucks... could there be a firmware fix for it? if the del key is held down, those same extra characters appear but it does register as a del key too.
On the plus I tested there were several additional problems inside the ASIC, no amount of Firmware fiddling is going to fix this.
Bryce.
Hey all :) so I have a CPC 464 which boots up seemingly pretty well to a small HDTV I have (although a slight image wobble which I'll leave for now)
But the keyboard isn't entirely working.
The Caps lock, c, b, n, m, /, \, plus 2 and + on the numpad won't respond. According to the technical specs, this makes sense - one of the lines on the matrix of the membrane has expired.
I've opened up the 464 and given everything a good clean and looked at the membrane. It all looks intact, so I guess a new membrane is needed.
Does anyone know where I can get one? :)
Quote from: Bryce on 22:36, 29 August 15
Unfortunately, this probably means that the ASIC is faulty and this isn't a part that you can get, other than removing one from another Plus. Which is kind of pointless. That's an ex-Plus you have there.
Sorry,
Bryce.
I know one shop selling asic chip but is no cheap :( .
Semiconductor: 40489 - AMSTRAD-IC GATE ARRAY (http://www.donberg.ie/catalogue/40489.html)
Amstrad made much more componets that plus computers builded :).
I had a 6128 in storage. I had cleaned the membrane carefully.
But some keys didn't work. I removed the membrane carefully cleaned the lines on the membrane where it goes into the connector. I used a bit of spit and cleaned it very carefully and dried it.
now all my keys work again!
So in my case, the membrane was good and I either needed to re-insert it again, or the end had become a bit dirty.
Two times I've done this and both times it worked great.
So try this if you've not done this already.
Quote from: gladders on 23:01, 21 October 15
Hey all :) so I have a CPC 464 which boots up seemingly pretty well to a small HDTV I have (although a slight image wobble which I'll leave for now)
But the keyboard isn't entirely working.
The Caps lock, c, b, n, m, /, \, plus 2 and + on the numpad won't respond. According to the technical specs, this makes sense - one of the lines on the matrix of the membrane has expired.
I've opened up the 464 and given everything a good clean and looked at the membrane. It all looks intact, so I guess a new membrane is needed.
Does anyone know where I can get one? :)
In motherboard keyboard connection, there is a sort of paper behind, pushing more the contact area, this paper does lose weight over time. Just add a paper more...
Quote from: gladders on 23:01, 21 October 15
Hey all :) so I have a CPC 464 which boots up seemingly pretty well to a small HDTV I have (although a slight image wobble which I'll leave for now)
But the keyboard isn't entirely working.
The Caps lock, c, b, n, m, /, \, plus 2 and + on the numpad won't respond. According to the technical specs, this makes sense - one of the lines on the matrix of the membrane has expired.
I've opened up the 464 and given everything a good clean and looked at the membrane. It all looks intact, so I guess a new membrane is needed.
Does anyone know where I can get one? :)
464 Membranes are pretty robust. Check first whether it's really the membrane by bridging a wire between the non-working line (at the connector on the PCB with membrane dis-connected) to any of the contacts in the other keyboard connector. That way you can be sure where the problem actually lies. If the characters still don't appear, the problem is on the PCB (most likely the AY-3-8912).
Bryce.
Sorry Bryce I am not that technical...what do you mean by bridging a wire? :( I don't have any equipment, just a screwdriver and some pliers!
No problem, no fancy tools or technical knowledge required. At the connector you need to take a piece of copper wire and connect it as shown in the picture below. Start at the top pin of the left connector and connect this pin to each of the contacts in the right connector one after another. Each time you touch them you should get a character on the screen (although not in all cases). Then move to the second contact of the left connector and go through all right pins again. If any of the characters you're missing (C,B,N,M etc) come up, then the mebrane really is the problem.
Bryce.
Thanks Bryce, I'll try to buy some wire from Maplins tonight and give it a go :)
I thought AY was controlling the keyboard on 6128 and on 464 was an intel chip :-X
Can't remember correct.
Quote from: VincentGR on 15:12, 22 October 15
I thought AY was controlling the keyboard on 6128 and on 464 was an intel chip :-X
Can't remember correct.
All CPCs have the same sound & keyboard chip, that way they are 100% compatible about that. :)
Quote from: Bryce on 10:32, 22 October 15
No problem, no fancy tools or technical knowledge required. At the connector you need to take a piece of copper wire and connect it as shown in the picture below. Start at the top pin of the left connector and connect this pin to each of the contacts in the right connector one after another. Each time you touch them you should get a character on the screen (although not in all cases). Then move to the second contact of the left connector and go through all right pins again. If any of the characters you're missing (C,B,N,M etc) come up, then the mebrane really is the problem.
Bryce.
I wrote an program to support this in an graphic way (see System Utilities), example here:
Keyboard Clash CPC6128 - YouTube (http://www.youtube.com/watch?v=wF0SbEJEO0A)
Quote from: Bryce on 10:32, 22 October 15
Bryce.
Hey Bryce, I haven't had the chance to test the keyboard as you suggest, but I have given the membrane a good clean and double checked everything else and it all looks fine, although I have noticed one of the connectors for the membrane's ribbons seems a very tiny bit loose on the motherboard, so I suspect it's that :(
Would you know who could repair it for me?
Actually, forget that - found a wire today and tested, and I can get those missing characters up! So it must be the membrane then?
Where do I find replacements, folks? :)
I think I have found the culprit having followed all the traces. All the faulty keys have one trace in common which gather into a single trace going into the ribbon that interfaces into the motherboard - and that trace has right at the end of the ribbon, a nasty scratch, on the black side.
How do I repair that kind of damage - silver paint as the other side, or something else?
I use "Silver Conductive Wire Glue Paste" to repair all kind of keyboards.
I even open a ZX+2 membrane in half to repair traces next to keys.
It works fine, it is elastic and drys almost instantly.
Quote from: VincentGR on 01:08, 26 October 15
I use "Silver Conductive Wire Glue Paste" to repair all kind of keyboards.
I even open a ZX+2 membrane in half to repair traces next to keys.
It works fine, it is elastic and drys almost instantly.
So do I apply it to either side of the membrane or just to the silver side? The damage that I see is on the 'black' side of the membrane ribbon, not the silver side...
The black side is where the conductor is, it needs to be added there.
Bryce.
As Bryce said.
Thanks, sounds weird considering people are telling me to get silver conductive and I'm ignoring the silver side :p
HAhHAHAAHAH
Explanation: The silver/carbon traces are black because they have oxidised. The other side still looks silver because the air can't get at it, you're looking at it through the plastic foil.
Bryce.
Ah I see!
So do I need to open up the whole thing to double check, risking tearing, or just worry about the ribbon?
Sorry for all the questions.
Quote from: gladders on 16:12, 26 October 15
Ah I see!
So do I need to open up the whole thing to double check, risking tearing, or just worry about the ribbon?
Sorry for all the questions.
I'd just repait the crack you can see and then retest. If it works, then leave it at that.
Remember: If it's not broken, don't fix it.
Bryce.
I am glad to report that following a dab of silver conductant, another CPC 464 is back to full health :)
Thanks for your help!
Congratulations, happy gaming.
Bryce.
Perfect!!!