dead keybaord after minor surgery

[ivansc]

Sorry to be a pain, but I have hunted high & low for the answer to this one:   Been a while since I had the cover off a 1200 & in installing a 2.5" hard drive in a newly-acquired A1200, I appear to have succeeded in mis-seating the keyboard ribbon cable.
I have reopened the case and double checked that the cable is now qaccurately installed, but sadly I now have no response from the keyboard on the QWERTYUIOP{} keys - all the others work OK so it looks like I zapped either an address line on the keyboard itself or on the keyboard chip.
Since I no longer even remember which chip controls the keyboard, any slightly more expert advice would be greatly appreciated, including any possible sources of keyboard chips if that is what I fried. *sigh*
Thanks in anticipation Ivan

[mikeymike]

I would have thought cable would be more suspect - check for dust/crap in the socket, and don't forget the clamps on either side of the socket...

I think I've done something similiar on my A1200, but down to improperly seated cable.

[that_punk_guy]

mikeymike, you neglected to say:

"Welcome to Amiga.org!"

:-)

[mikeymike]

You might have noticed that I have never said it :-)

[bloodline]

mikeymike wrote:
You might have noticed that I have never said it :-)

Never said what?

[that_punk_guy]

That's disturbing on so many levels.

(I don't know what that level thing is about, I just meant to say I'm disturbed by that, but the "on so many levels" thing sounds kinda cool, my new sig is bugging me because although it's more readable than the old one, and more stylish, it looks kinda strange like I'm not used to it and Dale just tried to eat an empty tin can and it was raining and sunny and all kinds of things at the same time today and I took this picture of myself with Dale, like in tha hood with graffitti on the walls and I realise I am not helping with this dude's problem.... Uh, let me see...)

Compressed air!

:-)

[KennyR]

No, I doubt if you zapped a chip.

The problem is more likely to be the ribbon cable itself - I once scraped the conductor off it when I put an HD in my A600 and I got no keyboard response at all when it was in.

The cure was a bit dramatic but it worked - i just snipped the scratched bit off with scissors, and reseated it in the socket.

[Castellen]

@punk_guy: :-P

@ivansc:
Yep, that's a fairly common problem.  I agree with KennyR that the keyboard microcontroller (the mask programmed HC705 beside the ribbon cable socket) should be fine.

When plugging in/removing the keyboard a few times, the conductive pads on the end of the ribbon cable get small holes scratched in them, and the connector pin no longer makes reliable contact.
Sometimes if you pull the ribbon about 1mm up from the bottom of the connector BEFORE pushing down the retaining clip it'll work good again.

Otherwise you can look carefully and see where the damage is, then trim a little off the end, so that the holes are below the connector's pins.

[Cass]

When plugging in/removing the keyboard a few times, the conductive pads on the end of the ribbon cable get small holes scratched in them, and the connector pin no longer makes reliable contact.

That's the problem, definatelly! I had a similar problem with the ribbon cable of my A600: Two rows wouldn't work... You may also try the graphite spray on the contacts (where the cable is scratched).

Another little problem on my A500 KB: the
Help ( ) / * +
Keys won't work! What's going on with this? The pads and the layer aren't worn, even though I cleaned & retouched with the graphite all the keys (there was no improvement :-( ).
________
Vapir No2 Vaporizer

[Castellen]

The A500 keyboard is a bit different to the A600/1200 as it's connected by serial data in the same fashion as the big box Amigas.

Take the keyboard apart and find the PCB track (row) which is common to the faulty keys and use a multimeter to check the track continuity from each keypad to the input pin of the keyboard microcontroller.
Chances are there could be a broken track, or dirt/grime on it somewhere causing the row to be held permanently active.

[Cass]

I've checked the plastic pad, up to its insertion on the microcontroller plate. It seamed to be OK, maybe is something at the pad's junction with the plate, or the microcontroller's circuit?

Anyway I have my A500 in Greece, and I'll have the chance to look it carefully on vacations...
________
20seh

[ivansc]

Dern you guys are quick!  Guess I suspected the ribbon cable all along but at my age (and with my geriatric eyesight) I was reluctant to start really LOOKING at the end of the cable. Still at least it is a no brainer to fix..... Thanks once again.
As a matter of interest, anyone have a cheap source of VGA to 23 pin adapters for Amiga video, and either an accelerator or a memory card for an Amiga1200? I am sick of mine telling me I have the date set wrong all the time & getting the R/T clock chip this way would be a good excuse to speed the little varmint up a bit! My other Amiga has a Blizzard 50hz card in it & the "new" one does seem like a real slug by comparison!
Thanks again for the help guys.

[Jope]

Another little problem on my A500 KB: the
Help ( ) / * +
Keys won't work!

What keymap are you running?

[Cass]

What keymap are you running?

I have to say that are the keys on the numeric keypad. As for the keymap, doesn't even matter: it's the plain ROM 1.3 default setup.
________
Free themes

[Jope]

Cass wrote:

What keymap are you running?

I have to say that are the keys on the numeric keypad. As for the keymap, doesn't even matter: it's the plain ROM 1.3 default setup.

Ah, young grasshopper, but that's where you're wrong. :-)

The default ROM keymap for 1.3 is an A1000 keymap - the extra keys in the numpad are missing on A1000 keyboards. You need to load a keymap to get them. USA is the ROM keymap, USA1 is the A2000/500 USA keymap and USA2 is dvorak. (just double checked the keymap names, it's been a long time since I ran 1.x daily ;-)