Hi all.
Recently I got myself a 6128 - a dream come true after all these years!
However, there were a few things wrong with it, like a dodgy disk drive and some dead keys.
Well, the drive was easy enough to sort out thanks to a new drive belt, but the keys are a different matter.
I've been doing a lot of research, and Gryzor and 00WReX (cheers guys!) have been providing a lot of advice and suggestions, but so far we are out of luck.
The following keys are dead:
DEL SPACE Z X V , .
and on the numeric keypad 0 and .
Of course most of you will recognise these as being on the same line on the keyboard membrane.
Now, I've gone over the membrane lines with a microscope, under a bright light, and I can't find any breaks or fractures.
I've cleaned the keyboard contacts both on the motherboard keyboard connectors and on the keyboard ribbon.
I've removed all the dust and grime I could find.
But nothing has helped. The same set of keys are still dead. :'(
I've even pressed the contacts on the membrane directly while the cpc was on, and that same set of keys were the only ones that didn't work.
Does anyone have any suggestions?
Is there some way of checking where the break is using a multimeter (is that what it's called?) or something like that?
I learned from 00WReX that both the AY chip and joystick logic passes through the keyboard connector circuits, and those all work fine, so the connectors on the motherboard must be ok.
Could there be a fracture in the ribbon in the bit that plugs into the motherboard?
(ie. the part of the line hidden behind the thin bit of plastic)
Could I (should I???) perhaps trim the ribbon and check if the newly exposed lines will work?
:o
Thanks for any help.
Definately good to get others input...but just to clarify, I mentioned that the keyboard connector circuits go off from the connector into both the AY sound chip as well as the 74LS145 decoder chip.
You mentioned that you get no "X" from the keyboard but the Joystick fire button produces an "X". So my thought is that hopefully this indicates that the AY chip & decoder chip are actually OK.
But the actual keyboard ribbon cable connector socket on the motherboard could still be the issue...even a dry solder joint, etc.
Just for reference, attached is the keyboard switch matrix and the keyboard connector component of the schematic diagram.
Ervin's 6128 has lost all the keys off connector no.10 in the switch matrix...
Cheers,
Shane
Don't know if this is of any help but I had a fracture in my Spectrum +3's keyboard ribbon, rendering some of the keys inoperative. I simply applied some graphite over the fractured point with a pencil and the keys started to work.
You said that you didn't see any fractures but I suppose it wouldn't hurt to try to apply graphite on the exposed part of the ribbon on to the suspected line.
I may as well give it a go!
Thanks.
Even if you can't see the fracture, it's good to go over the track with some conducting silver paint, which you can get in most good electronic suppliers. That usually solves most problems.
Bryce.
Quote from: Bryce on 19:23, 07 April 12
Even if you can't see the fracture, it's good to go over the track with some conducting silver paint, which you can get in most good electronic suppliers. That usually solves most problems.
Bryce.
Thanks Bryce. I'll try that.
Just wondering though, on the 6128 keyboard membrane, the tracks themselves aren't accessible. They have a black coating over them inside the membrane. Will tracing over those with conducting paint work?
In any case, this means that I have to take the dual-foil membrane apart, doesn't it? :o
I think what Bryce is talkng about is described & shown in pictures quite well here (but Bryce may want to confirm this)...
http://www.migman.com/eq/saitek/pc-dash-repair.php (http://www.migman.com/eq/saitek/pc-dash-repair.php)
Not a CPC but the idea can be for any connector of this type.
Cheers,
Shane
Quote from: 00WReX on 05:57, 08 April 12
I think what Bryce is talkng about is described & shown in pictures quite well here (but Bryce may want to confirm this)...
http://www.migman.com/eq/saitek/pc-dash-repair.php (http://www.migman.com/eq/saitek/pc-dash-repair.php)
Not a CPC but the idea can be for any connector of this type.
Cheers,
Shane
That's a fantastic link!
Thanks (once again!) Shane. I can't wait to give it a go!
Can't do it tonight though - family Easter duties. ;D
Alrighty, I'm now a bit confused!
(Sorry about all of this, but I don't know very much about electronics)
Here is one side of the connector containing the non-working line.
(http://i69.photobucket.com/albums/i57/poppichicken/1.jpg)
Here is the other side:
(http://i69.photobucket.com/albums/i57/poppichicken/2.jpg)
Am I supposed to be tracing over the black line in the first picture?
(The black line corresponding to the faulty line).
:-[
Yup the black line! :)
Yes, that's exactly what I meant, but just the first centimetre of the track. Sand the tracks with a very fine sandpaper first, it will give you a more reliable result.
Bryce.
Quote from: Badstarr on 17:46, 08 April 12
Yup the black line! :)
Cool, thanks. :)
That's exactly the sort of confirmation I need, to stop me being scared!
Quote from: Bryce on 22:06, 08 April 12
Yes, that's exactly what I meant, but just the first centimetre of the track. Sand the tracks with a very fine sandpaper first, it will give you a more reliable result.
Bryce.
Fantastic, thanks Bryce.
I'll go and get some fine sandpaper today, and give it a go!
The thought of ruining the ribbon is making me paranoid, but with all the information that you guys have given me, I'm feeling a lot more confident.
Remember to be very gentle with the sandpaper, you don't want to rub the contact away or damage the cable...just a light buff is all.
Just like the person in the link mentions...
And definately make sure you have nothing coarser than 800 grade sandpaper...remembering that the lower the number the coarser the sandpaper.
Quick chart - Sandpaper
30 grit
60 grit extremely coarse
80 grit
100 grit
120 grit recommended for general purpose, drywall patches, furniture re-finishing
180 grit
220 grit
240 grit recommended for general purpose, furniture
320 grit
400 grit recommended for fine finishing, polishing, gilding
600 grit
800 grit
1000 grit recommended for fine polishing, hand rubbed finishes and gilding
1200 grit
1600 grit extremely fine. Polishing, jewelry
Cheers,
Shane
If you have a multimeter you will be able to check the continuity on the lines once the fluid has dried. Just be careful you dont scratch the traces with the probes. A cheap and cheerful multimeter will do and will prove useful for many CPC repair projects. If your repair does not solve the problem you can easily use it to check the connections to the AY sound chip and the decoder chip to make sure the problem doesn't reside there. Either way good luck with the repair!
Quote from: Badstarr on 11:20, 09 April 12
If you have a multimeter you will be able to check the continuity on the lines once the fluid has dried. Just be careful you dont scratch the traces with the probes. A cheap and cheerful multimeter will do and will prove useful for many CPC repair projects. If your repair does not solve the problem you can easily use it to check the connections to the AY sound chip and the decoder chip to make sure the problem doesn't reside there. Either way good luck with the repair!
Thanks Badstarr. That's exactly the sort of thing I need to know.
I hope it isn't anything other than the membrane ribbon though. If it is, I'll probably be well and truly stuck. :'(
Well, looks like I won't be needing this thread any more.
:'( :'( :'(
Thanks everyone for your input and advice.
May I direct everyone's attention to this thread instead?
WTB: 6128 keyboard membrane (http://www.cpcwiki.eu/forum/classifieds/wtb-6128-keyboard-membrane/msg43766/#msg43766)
Failing that, is it possible to hook up an external keyboard to the 6128 somehow?
I know of the CPCKey project, but there's no way in hell I'd be able to construct something like that.
Still not working?? Is it possible that your CPC has the wrong keyboard installed? I know there are a few different layouts for the CPC, its just a hunch really, maybe someone with a bit more knowledge in this area can advise you. All the CPCs I have, have the same layout apart from my first generation 464 which has different connectors anyway.
Another thing that may be worth trying is to jump the connections from the keyboard connectors on the main PCB to check if the missing letters come up on screen. If they do then you know all you need is a working keyboard, its just a mystery as to why your keyboard doesn't work. Have you checked the membrane inside the keyboard unit?
There are no other keyboard projects for the CPC and due to the way the CPC reads the keys, all other/new keyboard projects would be as complicated as the CPCKey project.
So what exactly went wrong? Do you have pictures? How about sending the membrane to someone who has experience doing this type of repair? Or have you really destroyed it?
Bryce.
What happened ?? This does not sound good at all...
Well, let's just say I was a bit too thorough, when I gave the connector on the non-working line a "gentle" sanding.
I thought I was exposing the line under the black stuff. Unfortunately, I was actually exposing the plastic ribbon material itself, through the black stuff. And the worst thing is that I did it to all 8 lines. When I realised what I had done, I panicked, and "cleaned" it all up by neatly sanding off the lines from the end of the connector.
I really cannot begin to explain what the heck I was thinking.
Since then, I've tried using a conductive silver pen on the original dead line, and that didn't work.
I haven't tried that on the other lines yet (i.e. the lines that originally worked).
I also tried cutting a long, thing piece of aluminium foil, and sticking it to the good part of one of the other lines, and then into the keyboard connector. The good news is that it made that line of keys work! The bad news is that the same technique didn't work on the originally-dead line. Which of course means that the originally-dead line has a problem elsewhere.
I wish I had just let it be, and put up with my mostly good keyboard!
I reckon this calls for more gratuitous use of the "Cry" smiley:
:'( :'( :'( :'( :'(
A bummer, but not the end of the world. I'm sure a replacement can be easily sourced.
Bryce.
Quote from: Bryce on 15:21, 10 April 12
A bummer, but not the end of the world. I'm sure a replacement can be easily sourced.
Bryce.
I really hope so.
I know that in the grand scheme of things, this is one of those "meh, so what?" kind of things, but it is indeed a bummer, as I've wanted a real CPC for such a long time, and now that I've got my hands on one, I've messed up.
Anyway, I won't give up.
8)
:o :o :o
Ahhh...nooooo...
:( :( :(
Don't beat yourself up too badly (easier said than done, I know), these things do happen though...It will all turn out OK.
I will definately keep a good eye out for one...my 6128's are functional, so a bit reluctant to dismantle a worker, but one will definately come up that's for sure...
Trouble is, I suppose it's still not 100% proven that it's the membrane that's the issue...well, it is now but you know what i mean.
Shane.
Quote from: 00WReX on 15:36, 10 April 12
:o :o :o
Ahhh...nooooo...
:( :( :(
Don't beat yourself up too badly (easier said than done, I know), these things do happen though...It will all turn out OK.
I will definately keep a good eye out for one...my 6128's are functional, so a bit reluctant to dismantle a worker, but one will definately come up that's for sure...
Trouble is, I suppose it's still not 100% proven that it's the membrane that's the issue...well, it is now but you know what i mean.
Shane.
Yep, I'll keep my eyes pealed for one!
Ironic isn't it? In trying to fix what *may* have been a small problem, I've created a much bigger one.
Just thinking about it...did you only rub the 1st centimtre or so...roughly only the area above (on top of) the white backing section ??
Maybe all is not lost...maybe, possibly, you could cut the ribbon just above the white backing section and start again...
Can you post up a picture ??
Not sure if it will work, but it's sounding like you have not got much to lose at the minute...
Shane.
Quote from: 00WReX on 15:49, 10 April 12
Just thinking about it...did you only rub the 1st centimtre or so...roughly only the area above (on top of) the white backing section ??
Maybe all is not lost...maybe, possibly, you could cut the ribbon just above the white backing section and start again...
Can you post up a picture ??
Not sure if it will work, but it's sounding like you have not got much to lose at the minute...
Shane.
That's exactly the next thing I'm going to try.
Do you have any recommendations regarding the type of glue to use, to stick the thick plastic to the end of the ribbon?
(i.e. remove the rigid plastic strip from the current end of the ribbon, and stick it to the "new" end of the ribbon).
I'm way too embarrassed to post a picture of the way it looks at the moment.
It's all a bit of a dog's breakfast.
:(
Not sure about the best glue to re attach the rigid white section...let me think about it (getting late, I need sleep).
BUT...do not worry about that part just yet. Really that white backing section is just to add thicknes to the ribbon to press it against the contacts in the connector & also to add rigidity to the ribbon when inserting into the connector.
You could probably, I'm pretty sure just hold it firmly against the the rear of the ribbon when you insert it...that would probably be good enough for starters to just see if the ribbon fix has worked...
Shane
Good plan. You can re-glue the white plastic bit with any general glue, but I would probably choose some type of super-glue. Move the white bit first, then cut the ribbon. Also, the tracks are standard 2,54 pitch, 1.8mm width. I would suggest making some sort of mask/template to temporarily tape onto the ribbon to make the silver paint job a little bit easier and neater.
Bryce.
Thanks guys.
I *should* be asleep now, but I can't let it go.
I've cut off the end, and found that the rigid plastic bit is still quite self-adhesive.
So I've stuck it onto the new end of the ribbon.
I've also applied conductive ink to the tracks (using a toothpick) as neatly as I can.
Once it has dried and cured, I'll give it a test.
Probably at this time tomorrow night!
Alrighty, I'm off to get some shut-eye.
Man, this thread makes me sad, really. :(
Let us know how it went when you wake up!
Hi Gryzor.
I tried the "fixed" connector this morning before breakfast, and it didn't work. I'm not sure why.
:(
Anyway, today I went to an electronics store and got myself a multimeter, with a view to trying some other things tonight.
Luckily, before I began, I logged on to this wonderful forum (it's always my first stop on the net), and I found a very generous offer from ynot.zero regarding a 6128 keyboard membrane.
;D
I think I'll see how that goes before I do any more surgery on my broken membrane.
I am once again full of hope!
Fingers crossed!
Yay for the community then. Even if you don't find out what's wrong with the one you have...
However, it's a shame because you'll have to wait to use the HxC :(
Quote from: Gryzor on 15:09, 11 April 12
Yay for the community then. Even if you don't find out what's wrong with the one you have...
However, it's a shame because you'll have to wait to use the HxC :(
That is indeed true... but if the replacement keyboard is successful, at least I
will be able to use the HxC!
;D
Okay, using the multimeter, I've identified where the problem is.
And it appears to be the place where the original problem was, before I stuffed it all up!
It's the spot where all 8 lines come together, where the 2 foils are stuck together over the spot where all 8 lines "merge".
Taking the membrane foils apart has made the problem much worse, as now none of the 8 lines have conductivity over that point where the 8 lines merge. It appears that when I pulled the foils apart, it damaged the lines. Sigh...
I did a heck of a lot of testing with my cheap and cheerful multimeter, and it didn't matter where I tested on the originally non-working line - there was conductivity. Once I put on of the probes on or past the merging of lines, I lost conductivity.
I *may* be able to fix it, but it will take a lot of time and patience, and a steady hand.
Most likely my attempt will fail.
Nonetheless, if the replacement is ok, I won't be trying to fix this one anymore.
I guess the upshot of all this is that the membrane is pretty much fine, apart from the merging bit.
All the key pressure pads appear to work.
WARNING: long (but hopefully fascinating) post ahead!
(BONUS: Ridiculous photos included at the end!)
Alrighty, the replacement membrane from ynot.zero is on the way.
I am so grateful - I can't even begin to express how thankful I am. :)
While I wait for it to arrive, the dead membrane of course continues to haunt me.
Last night I stayed awake way too late trying various things with aluminium foil tape and a multimeter.
The first few ideas I had showed brief sparks of promise, but really didn't get anywhere.
I discovered that aluminium foil tape doesn't conduct particularly well, when you stick smaller lengths of it together in order to make longer traces.
So I thought, why not stick two fat bits of the foil tape together (adhesive side to adhesive side), and then trim it to a narrow strip?
I did so, and of course it was conductive across the length of the strip.
I then started by sticking one end to the bit that goes into the motherboard keyboard connector (being careful to leave aluminium exposed on the bit which actually plugs in to the connector). Then I used narrow strips of non-conductive adhesive tape to stick the foil to the membrane, along one of the black lines.
Where the black line bent around corners, I folded the aluminium foil strip over itself to change direction.
I worked my way around to the first circular sensor thing, carefully covering the foil strip with tape as I went along.
When one line was done, I tried plugging the membrane back into the cpc.
And holy cow... it worked. The numbers along the top of the keyboard, that are connected to that membrane line, all worked! I could not believe it!
I then did the same for the second line. Because I had covered the first line in tape, the second repair line remained isolated from the first repair line, and after some patient folding, sticking, and multimeter testing, I had a working second line!
As it stands now, all the keys along the top (connected to the first two trace lines) work!
EXTREMELY HACKY, but it works! ;D
(Could this be one of the hackiest keyboard fixes/mods ever?)
I'm not sure it's worth trying to fix the entire membrane, as it will become a rather messy amalgamation of aluminium foil and adhesive tape, but I'm just excited that I've been able to make some of it work using my crude and clueless techniques!
(http://i69.photobucket.com/albums/i57/poppichicken/foil1-1.jpg)
(http://i69.photobucket.com/albums/i57/poppichicken/foil2-1.jpg)
Regardless, none of this will matter if the replacement membrane is in good condition. But I had to try, didn't I?
:)
Hahaha, good to see you persist with it...sounds like you are learning a bit along the way, especially now that you have a multimeter.
Just wondering why you went so far with the aluminium foil...If those lines were working prior to you sanding the connnector away, would have thought you would only need to go only a few centimetres along the ribbon, and not even get near the actual membrane ??
It may be required for you original faulty line though, have you had any luck testing the continuity with your multimeter and in indentifying the break (on the original faulty line) ?
Is one of the lines you have attempted to re-create the original faulty one (without pulling one of mine apart, i can't remember what line looks after what key range) ?
Cheers,
Shane
Quote from: 00WReX on 03:40, 13 April 12
Hahaha, good to see you persist with it...sounds like you are learning a bit along the way, especially now that you have a multimeter.
Just wondering why you went so far with the aluminium foil...If those lines were working prior to you sanding the connnector away, would have thought you would only need to go only a few centimetres along the ribbon, and not even get near the actual membrane ??
It may be required for you original faulty line though, have you had any luck testing the continuity with your multimeter and in indentifying the break (on the original faulty line) ?
Is one of the lines you have attempted to re-create the original faulty one (without pulling one of mine apart, i can't remember what line looks after what key range) ?
Cheers,
Shane
Yep, I certainly am learning quite a lot. Being a stubborn bugger certainly helps!
Though I won't be building my own circuit board just yet! :)
The foil tape had to go onto the membrane because when I pulled the membrane apart, the glue that was holding the 2 halves together must have taken some of the black line with it, right where the ribbon expands out into the rest of the membrane. I probably went a bit further than I needed to, possibly out of paranoia, or perhaps enthusiasm. ;D
The original faulty line hasn't been fixed yet.
(It's the one at the top of the photos).
I thought I'd test some lines that used to work before I broke it all.
From what I understand, it appears that the original problem was caused by pretty much the same problem (though it wasn't caused by me!). According to my multimeter tests, the entirety of the original line is fine along the membrane, but at the point where it all converges to the ribbon, conductivity is broken.
Ahh, I see...thought there must be a reason for those lengths of foil.
Yeh, I know what you mean about being stubborn...got a bit of that myself, get something in my head and I can be like a dog with a bone.
All good though because you tend to learn a bit.
Cheers,
Shane
Just re-read a couple of earlier post's...yes you did already mention the pulling apart of the membrane damaging the lines...
I forgot all about that bit ::) And I had read it previously ???
I blame it on old age :D , along with too much work & not enough sleep ;D
Cheers,
Shane
Quote from: 00WReX on 06:20, 13 April 12
Just re-read a couple of earlier post's...yes you did already mention the pulling apart of the membrane damaging the lines...
I forgot all about that bit ::) And I had read it previously ???
I blame it on old age :D , along with too much work & not enough sleep ;D
Cheers,
Shane
:laugh:
No problem, a lot of stuff has been discussed in this thread, so it's easy to forget what has happened thus far.
I'm with you there on old age, too much work and not enough sleep!
Speaking of old age, it's amazing to think that I defeated Jet Set Willy 26 years ago, and Head Over Heels 25 years ago. And I still remember those moments!
Uh oh, time to go wildly off topic!
I remember seeing Alien 8 for the first time, in what was then my local computer store.
I even remember the colour scheme of the screen that I first saw (red and yellow, with orange from stippling), which way I was facing and where the cpc was in relation to the door of the shop!
Same thing with Elite. I can remember the moment like it was yesterday.
Funny the sorts of things that stay in memory eh?
I often wonder if my unhealthy desire to have a working 6128 is a result of trying to hang on to those moments so tightly, tooth and nail.
Totally agree with you mate.
I think the "hanging onto fond memories" aspect is probably the case for a fair few people, not only on this forum...but people who still use & collect retro things in general.
Did you have an Amstrad back in the day or did you use a mates ?
I have a few interesting stories (well interesting for me) around a few of my CPC's and how I obtained them, but might bore others to death.
Just quickly...
I still have my original 464 from 1985...and it is in mint condition...I also have the very first 464 I laid eyes on and used...my good mates one.
I also have a couple of ex South Australian High School 6128's (what was Strathalbyn High School), another long story with those.
Both my mates & the high school computers I obtained in 2003 after chasing up some real long shot's and not very likely leads...
Just recently my nostalgia got the better of me & I purchased a small collection of another brand 8-bit computer, purely because I had fond memories of using them as my local High School computer for the duration of my time there.
Anyway, I've already gone on too much...old age again, now I'm telling stories...
Cheers,
Shane
That's brilliant - I love reading stories like that.
"When I was a boy..." :laugh:
I did indeed have a cpc back then - a 464 with green screen monitor!
On special occasions the MP1 was used to add a bit of colour to proceedings.
I remember the first time I saw Sorcery running in colour - my jaw just dropped.
Gryzor was of course just mindblowing as well.
I went to (long since closed) West Lakes High School back in those days, and they had a room full of 6128's.
I knew how to use them better than the teacher; not many people had home computers back then.
We used Tasword a lot to learn how to "use computers".
And we played some crappy cricket game with stickmen when the teacher wasn't nearby. :)
[EDIT] I think it was this one: http://www.cpc-power.com/index.php?page=detail&num=2207 (http://www.cpc-power.com/index.php?page=detail&num=2207)
It'd be amazing if I could find out whatever happened to those 6128's, but I wouldn't even know where to start.
I suspect that some of the teachers may not even be with us any more... time marches on.
I had a few friends with CPC's, and some with C64's, so I got to play on both sides of the fence.
Great days indeed.
A few of our stories can be found here...
Your Earliest Memory of the CPC? (http://www.cpcwiki.eu/forum/general-discussion/your-earliest-memory-of-the-cpc/)
and here
NEW ATARI 600XL COMPUTER IN CLOSED NEVER OPEN BOX (http://www.cpcwiki.eu/forum/other-retro/new-atari-600xl-computer-in-closed-never-open-box/msg33549/#msg33549)
;D
Cheers,
Shane
Fantastic stuff!
Might be time to re-read that earliest memories thread.
Your post in the atari 600xl thread about how you got those 2 6128's is astonishing.
You lucky bugger! ;D
That lot must be worth quite a bit, though I can't imagine you'd ever want to sell any of it!
QuoteI knew how to use them better than the teacher; not many people had home computers back then.We used Tasword a lot to learn how to "use computers".
I know that feeling. When I was in school we also had CPC6128's and I used to do my assignments in 510 minutes and then played Camelot Warriors with my teacher 8)
Also, a great moment I remember is when I brought Samantha Fox Strip Poker... boy, what a show! ;D
Sorry for breaking up you trip down memory lane and wandering back to original subject:
Cool fix erwin, but I doubt it would last very long and to put it in Australian speak, it's probably as reliable as a 80's Holden, but well worth the bother just for the learning aspect.
Bryce.
Quote from: Bryce on 09:30, 13 April 12
Sorry for breaking up you trip down memory lane and wandering back to original subject:
Spoil sport ;D
Quote from: Bryce on 09:30, 13 April 12
Cool fix erwin, but I doubt it would last very long and to put it in Australian speak, it's probably as reliable as a 80's Holden, but well worth the bother just for the learning aspect.
Bryce.
That's totally unfair Bryce...an 80's Holden would never have been that reliable :D
Anyway, where did you learn about the Aussie Holden ? (woops, off topic again) :)
Cheers,
Shane
I guess that multimeter is earning its keep! Congratulations on at least restoring some functionality, any victory in these matters represents a good learning experience. The keyboard I'm using on my GX4000 plus modification is getting a little problematic I think it may be a faulty membrane as all the connections seem ok so I may have to use the keyboard from the faulty 6128 I just bought. Well at least as a temporary solution. I suppose the keyboard membrane gets the most mechanical punishment so some problems are to be expected. I might have a try making a membrane from scratch when I have the time, just for the hell of it ;D
Quote from: Bryce on 09:30, 13 April 12
Sorry for breaking up you trip down memory lane and wandering back to original subject:
Cool fix erwin, but I doubt it would last very long and to put it in Australian speak, it's probably as reliable as a 80's Holden, but well worth the bother just for the learning aspect.
Bryce.
Yeah you're probably right, it likely isn't the most reliable solution.
Incidentally, I've always driven Holdens, and they've been great!
I've now got 4 lines wired up, including the one that caused all this hassle in the first place.
Out of those 4 lines, it's that original one that now
still isn't working with my hacky fix!
>:(
I get a reading on the multimeter from the space bar's sensor to the ribbon, so the keys are actually registering.
It seems that the keyboard connector might be the culprit.
Grrr... all this hassle because of that!
[EDIT]
Then again I'm not so sure.
When I use multimeter probes from the top of the connector (on that line) to the soldered bit under the connector (where the connector plugs into the motherboard), I get a reading. So at least current is indeed flowing through the connector on that line.
But I don't know where else to look. :(
I can't tell on the back of the motherboard where those lines lead. They're really thin and many lines don't actually seem to connect to anything...
Quote from: Badstarr on 13:31, 13 April 12
I guess that multimeter is earning its keep! Congratulations on at least restoring some functionality, any victory in these matters represents a good learning experience. The keyboard I'm using on my GX4000 plus modification is getting a little problematic I think it may be a faulty membrane as all the connections seem ok so I may have to use the keyboard from the faulty 6128 I just bought. Well at least as a temporary solution. I suppose the keyboard membrane gets the most mechanical punishment so some problems are to be expected. I might have a try making a membrane from scratch when I have the time, just for the hell of it ;D
Yeah not bad for a cheap and cheerful unit!
(It was only $10).
Making a membrane from scratch would be fascinating. What would you use to create the lines for each key group?
Quote from: 00WReX on 09:38, 13 April 12
Anyway, where did you learn about the Aussie Holden ? (woops, off topic again) :)
I know they brought the Monaro over to the UK a few years back, not sure if they released it in Europe via Opel?... wouldn't mind owning one to hoon around in :D
Vauxhall Monaro (http://en.wikipedia.org/wiki/Holden_Monaro#Vauxhall_Monaro)
Depending on which flat cable you're actually fixing/testing - One of the sockets is connected directly to IC101 (74LS145) pins 1 to 11 (skipping pin 8). These are the output signals to the keyboard. When the CPC is running, the keyboard is scanned by switching one of these pins to GND one after another. The other flat cable is connected directly to the AY, pins 7 to 14. If a key is pressed, the corresponding pin of the AY will go low and the CPC knows what you've just pressed. Test each pin of both connectors to the ICs to make sure each connection is really working.
Bryce.
Quote from: Bryce on 13:59, 13 April 12
Depending on which flat cable you're actually fixing/testing - One of the sockets is connected directly to IC101 (74LS145) pins 1 to 11 (skipping pin 8) . These are the output signals to the keyboard. When the CPC is running, the keyboard is scanned by switching one of these pins to GND one after another. The other flat cable is connected directly to the AY, pins 7 to 14. If a key is pressed, the corresponding pin of the AY will go low and the CPC knows what you've just pressed. Test each pin of both connectors to the ICs to make sure each connection is really working.
Bryce.
Alrighty, I've been doing just that.
And it looks as though all the messing around with the keyboard has been a waste of time.
One of the pins of the AY appears to be dead. So it's hopeless. I have no idea how to fix this. :'(
I ruined a perfectly good membrane because I didn't know what I was doing.
I went along the AY pins, and matched up the pins with the pins on the keyboard connector.
All of them had current except the one that (I think) connects to the line that SPACE etc are on.
Apologies for the photo quality:
(http://i69.photobucket.com/albums/i57/poppichicken/ay1.jpg)
(http://i69.photobucket.com/albums/i57/poppichicken/ay2.jpg)
@ervin: You could try to smudge some graphite over the remaining lines with a pencil. Worked for my +3 membrane and it is a commonly known way of unlocking old Athlon and Duron cpu multipliers.
Quote from: protek on 14:12, 13 April 12
@ervin: You could try to smudge some graphite over the remaining lines with a pencil. Worked for my +3 membrane and it is a commonly known way of unlocking old Athlon and Duron cpu multipliers.
Great idea! I'm off to try it right now!
That's not going to help if it's the AY that's dead. Are you sure that the pin isn't working? Define it "not having current"? Do you mean it doesn't connect to the connector?
Bryce.
Quote from: Bryce on 14:29, 13 April 12
That's not going to help if it's the AY that's dead. Are you sure that the pin isn't working? Define it "not having current"? Do you mean it doesn't connect to the connector?
Bryce.
I think the AY itself is ok.
Certainly when I press CLR, I get that familiar beep.
When I multimeter between the faulty little silver dot (techie term :) ) and the AY leg thing, 7 out of the 8 that I presume connect to the keyboard connector show current.
It's when I try to check the little silver dot (second silver dot from the left in the second photo above), there is no current between it and the corresponding AY leg.
EDIT: I've just read that post back to myself - I sound so clueless!
Ah well, let's face it, I am!
EDIT 2: I've had a look at the AY underneath the motherboard.
Everything seems clean and intact.
It's just the bit on top that stuffed.
Incidentally, I'm amazed at how compact the motherboard is. Just seems so small compared to modern boards.
Of course, it is around 1 million times simpler!
Why are you measuring the little dots, you should be measuring between the cable connector and the AY pins.
Bryce.
Quote from: Bryce on 14:42, 13 April 12
Why are you measuring the little dots, you should be measuring between the cable connector and the AY pins.
Bryce.
I tried that, and there is no current between the cable connector and the bad pin.
(However, there IS current between the cable connector and the dot in front of the bad pin).
The other pins do show a reading between themselves and the cable connector.
I just noticed that on the other AY pins, there is current between the little dots and their respective pins, but the bad pin doesn't.
Is there any damage to the PCB in that area (check the bottom side too)? Maybe the track is broken? If the AY is ok, you may have to make a wire link from the AY pin to the correct connector pin.
Bryce.
Just a quick question from me,
Ervin has indicated that the "X" on the keyboard is not working but when the joystick fire button is pressed it produces an "X".
I would have though this would have been using the same data line into the AY at some point ?
Cheers,
Shane
Yes, but the pin he mentioned isn't responsible for the X either, so I assume the AY is ok and there is a break somewhere else.
Ok erwin, here's something to try. Get a piece of wire and starting with the first pin of output connector (keyboard doesn't need to be connected) hold the wire on pin 1 and then run the other end along the contacts of the input connector (the one attached to the AY), a row of characters will appear on the screen. Now do the same for pin 2 and so on. That way you will be 100% sure whether the PCB or AY really has a problem.
Bryce.
Quote from: Bryce on 14:50, 13 April 12
Is there any damage to the PCB in that area (check the bottom side too)? Maybe the track is broken? If the AY is ok, you may have to make a wire link from the AY pin to the correct connector pin.
Bryce.
The PCB appears to be ok. To my inexperienced eyes, at least.
Quote from: Bryce on 15:03, 13 April 12
Yes, but the pin he mentioned isn't responsible for the X either, so I assume the AY is ok and there is a break somewhere else.
Ok erwin, here's something to try. Get a piece of wire and starting with the first pin of output connector (keyboard doesn't need to be connected) hold the wire on pin 1 and then run the other end along the contacts of the input connector (the one attached to the AY), a row of characters will appear on the screen. Now do the same for pin 2 and so on. That way you will be 100% sure whether the PCB or AY really has a problem.
Bryce.
Thanks for the tip Bryce.
I've done as you have suggested, and here are some results:
In this picture, I've tested the line from the keyboard that isn't producing anything.
I presume the weird characters are related to the CTRL and DEL keys etc?
Anyway, V X etc are appearing, and they are the characters that aren't working with normal keyboard use.
(http://i69.photobucket.com/albums/i57/poppichicken/3.jpg)
Then I tested the next line in the keyboard connector.
The keys on this line work with normal keyboard use.
(http://i69.photobucket.com/albums/i57/poppichicken/2-1.jpg)
Does this mean that the AY is ok?
Yikes, the old keyboard continuity connection checking dance! Something I'm all too familiar with! Fear not though, from my brief skim through the recent posts on here I can see that a fix will most likely be possible! The worst case scenario is that you might have to do a little soldering to reinstate the connection that looks to be missing at the AY. It may be worth getting a decent soldering kit to keep your new multimeter company, you seem to be prepared to get your hands dirty which is a good thing! Everyone makes mistakes along the way to learning a new skill.
The AY connections should go direct to the poly connector where you plug the keyboard in, so you just need to trace the correct pin on the connector and solder a fly cable to the correct pin on the AY assuming its not just a simple dry joint situation, which seems fairly likely based on your description. Also check the schematics section on the main wiki as it's always good to have a map to guide you where you need to be, it may be all a bit confusing if you aren't familiar with electronics but take some time to study them and you will soon start making sense of them! But do always exercise caution though when working with electricity!
As for building a membrane I was thinking about going for a more robust option, maybe using some old fashioned wires and tougher plastic, I think Amstrad used a similar solution for one of the 464 keyboards and from what I remember they are considered practically indestructible!
I'm all with you badstarr, sound advice, but I think he should wait until the new keyboard has arrived. It's still not clear whether there's a problem on the board at all. If he plugs the good board in and it stil has problems, then he can start soldering IC pins, but until then, I'd hold back on the PCB experiments. You don't want to break anything further if it's not necessary.
Bryce.
Quote from: protek on 14:12, 13 April 12
@ervin: You could try to smudge some graphite over the remaining lines with a pencil. Worked for my +3 membrane and it is a commonly known way of unlocking old Athlon and Duron cpu multipliers.
That trick didn't work, but it did lead to something else...
IT IS WORKING!!!
;D ;D ;D
I dabbed a bit of conductive ink over the offending broken line (from the little dot to the AY pin), waited for it to dry, cured it under a bright light, and now SPACE, Z, X etc work for the first time!!!
I am so chuffed right now!
With my aluminum foil repair, I'm not too sure that the key repeat rate is consistent, but it's only a temporary solution, so that's ok.
THANKS EVERYONE for all of your help. I could never have done this without you.
WooHoo...well done, your persistence with this has been impressive.
Good to see you did not throw your hands in the air and give up. :)
Hopefully when the replacement membrane arrives it will all work as good as new.
Also just noticed that from the screenshot your 6128 is an "Awa" and not the later "Amstrad"...it's only a single link on the motherboard that changes this, but it indicates yours is an earlier Australian delivered 6128. Cool. :)
Cheers,
shane
Thanks Shane.
It's been a heck of a ride, and it isn't over yet, but there is light at the end of the tunnel!
The hacky way I've fixed the keyboard isn't really ideal, as the key repeat rate seems a bit wrong, but it'll tide me over until a proper working membrane arrives.
Yeah, I noticed the "Awa". It means that this computer is 26 or 27 years old, I believe.
It's amazing that these things still work after all these years!
Oh man, this is touching indeed =) Have lots of fun! And, hey, what about the HxC?
Thanks Gryzor.
The HxC hasn't arrived yet.
Hopefully it'll arrive this week, I can't wait to try it.
Hi all.
Just wanted to let you know how this has all ended up.
My aluminium foil method turned out to be a bit of a dud.
I just couldn't get all 8 keyboard lines to work consistently, and without "cross-contaminating" each other with current.
So in a fit of rage I ripped them all off.
(Actually, I removed them really carefully).
I then tried various ideas, related to conductive ink, foil and conductive ink, conductive silver paint, more ink, more paint, more foil etc. etc. etc. I'm surprised that I had the patience to try so many things, quite frankly!
Anyway, in the end I came up with a successful solution!
The 8 tips of the membrane were re-created using aluminium foil tape, cut into short, narrow strips.
I then painted over the entire narrow part of the membrane with conductive silver paint. :o
Once that dried, I etched gaps between the 8 lines using a sharp object. 8)
In the end, I had 8 lines connected to the main membrane body with the paint, and at the end of narrow part of the membrane the aluminium foil strips connected with the paint.
And it worked! Some keys had a sort-of-rubbery feel to them for some reason, and (as I've mentioned before) the key repeat rate seemed slightly off and inconsistent, but that's okay, because I had a fully working keyboard! (Even the keys that didn't work and led me on this adventure in the first place).
Here's how it looks.
(http://i69.photobucket.com/albums/i57/poppichicken/Photo1.jpg)
(http://i69.photobucket.com/albums/i57/poppichicken/Photo2.jpg)
(http://i69.photobucket.com/albums/i57/poppichicken/Photo3.jpg)
(http://i69.photobucket.com/albums/i57/poppichicken/Photo4.jpg)
It isn't a perfect solution of course.
And that's where ynot.zer0's generosity has come in.
The VERY SAME DAY that I got the above solution finished, my replacement membrane arrived.
I gave it a good thrashing, and it all works perfectly.
No rubbery key response, no key repeat problems.
Just a perfect 6128 keyboard. AT LAST.
;D
Okay, that's enough from me.
Thanks again everyone for all your help and suggestions.
This is a wonderful community that I feel very privileged to be a part of.
Good to hear your keyboard is now finctioning perfectly. :)
Well you certainly get my vote for "Most artistic / creative repair job 2012". I admire your perseverance. I would have given up two days earlier :D
Bryce.
Nice one mate, that's good to hear :) very nice of ynot.zer0 as well :)
Cheers,
Shane
Looks like a proper mess, but who cares, as long as it works. So, from what I understand it was a matter of conductivity after all?
;D
If you think
that looks like a mess, you should have seen how it looked at various points during all the crazy ideas I tried.
It's amazing that the thing is still intact!
:laugh:
Quote from: Gryzor on 13:39, 27 April 12
Looks like a proper mess, but who cares, as long as it works. So, from what I understand it was a matter of conductivity after all?
Yes, sort of - once I had started butchering the membrane (trying to figure out if it was indeed the cause of my original keyboard problems), it did indeed become a matter of conductivity.
But the original problem had nothing to do with the membrane. :-[
It was caused by a dead pin to the AY chip. This was fixed with a quick application of conductive silver paint.
(When I say quick, I mean
after all the time spent figuring out where the actual problem was, using a multimeter).
I'm still amazed that the butchered membrane works!