A500 Keyboard Problem

08 October 2007, 10:00

I'm trying to repair the keyboard on my old A500. I've seen a similar post on here where the guy could not reset with Ctrl+amiga+amiga keys. Mine has that problem, aditionally the number keys above the QWERTY keys don't work, nor does the + symbol but curiously the - does. The num keys on the numpad work, but most of the others don't

I assume the problem is on the keyboard PCB at the top right? There are no other problems I've noticed with the machine - it warms up straight away and boots without problems etc.

I've stripped the keyboard and looked for dead components but can't see any on a visual check and a quick checkout with the old multimeter reveals that most things seem okay. One of the small ceramic capacitors grudgingly gives a reading so I might change it. I haven't checked the two small transistors out in detail other than a quick continuity test across the two outermost legs. Is it worth changing these as a precaution? I had thought about desoldering them and testing properly as my multimeter does have a transistor tester.

Anyway.. I may well be barking up the wrong tree entirely, so any help is much appreciated.

CRAZG · 08 October 2007, 10:06

You may be able to pickup a non working A500 for the price of a resistor, and grab the keyboard off that.

Jope · 08 October 2007, 18:24

Ooops, wrong answer first. Sorry.

So .. get a new keyboard like has been suggested. Ebay should have them.

08 October 2007, 19:36

I was thinking about doing that, but I'd kind of like to fix this one. I have an A600 as well so I do have a usable machine so can wait to fix the 500 for a bit. Resistors and transistors cost pennies anyway.

Jope · 10 October 2007, 08:06

Either the membrane is broken or the keyboard controller. Open the keyboard, whip out your magnifying glass and start looking at the tracks that lead to your non-working keys.

Or just forget about it and get a cheap replacement kbd. :-)

10 October 2007, 14:08

Hmmm... Hadn't thought about the membrane being the problem. I don't fancy looking for faulty tracks on that! The keyboard worked fine last time the 500 was out, so I wonder if it's the controller.

I may well buy another for spares as the machine's not getting any younger ('87 model with '91 replacement motherboard) and I guess spares will only get scarcer, then maybe I can have a play fixing this keyboard afterwards...

08 October 2007, 10:00	#1
jonzo Posts: n/a	A500 Keyboard Problem I'm trying to repair the keyboard on my old A500. I've seen a similar post on here where the guy could not reset with Ctrl+amiga+amiga keys. Mine has that problem, aditionally the number keys above the QWERTY keys don't work, nor does the + symbol but curiously the - does. The num keys on the numpad work, but most of the others don't I assume the problem is on the keyboard PCB at the top right? There are no other problems I've noticed with the machine - it warms up straight away and boots without problems etc. I've stripped the keyboard and looked for dead components but can't see any on a visual check and a quick checkout with the old multimeter reveals that most things seem okay. One of the small ceramic capacitors grudgingly gives a reading so I might change it. I haven't checked the two small transistors out in detail other than a quick continuity test across the two outermost legs. Is it worth changing these as a precaution? I had thought about desoldering them and testing properly as my multimeter does have a transistor tester. Anyway.. I may well be barking up the wrong tree entirely, so any help is much appreciated.

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08 October 2007, 10:06	#2
CRAZG 2 heads are more than 1 Join Date: May 2007 Location: Tauranga / New Zealand Posts: 38	You may be able to pickup a non working A500 for the price of a resistor, and grab the keyboard off that.

08 October 2007, 18:24	#3
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	Ooops, wrong answer first. Sorry. So .. get a new keyboard like has been suggested. Ebay should have them.

08 October 2007, 19:36	#4
jonzo Posts: n/a	I was thinking about doing that, but I'd kind of like to fix this one. I have an A600 as well so I do have a usable machine so can wait to fix the 500 for a bit. Resistors and transistors cost pennies anyway.

10 October 2007, 08:06	#5
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	Either the membrane is broken or the keyboard controller. Open the keyboard, whip out your magnifying glass and start looking at the tracks that lead to your non-working keys. Or just forget about it and get a cheap replacement kbd. :-)

10 October 2007, 14:08	#6
jonzo Posts: n/a	Hmmm... Hadn't thought about the membrane being the problem. I don't fancy looking for faulty tracks on that! The keyboard worked fine last time the 500 was out, so I wonder if it's the controller. I may well buy another for spares as the machine's not getting any younger ('87 model with '91 replacement motherboard) and I guess spares will only get scarcer, then maybe I can have a play fixing this keyboard afterwards...

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