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Old 30 October 2010, 23:17   #1
orange
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A500 keyboard, reset problem

Strangely one A500 here won't reset unless the keys are pressed for about 6seconds or more. is that normal? (because the manual says to always wait 5sec or something)
when pressed shortly caps lock blinks one time and there is no reset.
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Old 30 October 2010, 23:22   #2
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Does this machine have a ROM switcher inside it? Some automatic ROM switchers used the old 'three finger salute' to change ROMs.

It could just be dirty contacts on the keyboard though.
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Old 31 October 2010, 00:10   #3
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no ROM switcher.the kbd contacts seem fine, everything else works.

could it be some capacitor that takes time to 'fill up'?
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Old 31 October 2010, 01:54   #4
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That was going to be my next suggestion, that the caps need to be replaced. Electrolytic caps can have that 'ramp' effect that you describe, particularly if they have dried out or leaked.

Take a good look at the caps, to see if any have 'raised' or 'domed' heads, compared to others on the board; that's a strong clue that the capacitor has failed.
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Old 31 October 2010, 18:05   #5
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they all look normal. I need schematics for that little PCB, anyone got it?
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Old 31 October 2010, 20:01   #6
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Quote:
Originally Posted by orange View Post
they all look normal. I need schematics for that little PCB, anyone got it?
What little PCB? As fas as I am aware, the standard A500 doesn't have a little PCB; do you know if your machine has been upgraded at all?

It sounds as if someone has added in a RAM upgrade at some time in your machine's past. How much memory does your machine display at the Workbench screen?
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Old 31 October 2010, 20:43   #7
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Quote:
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they all look normal. I need schematics for that little PCB, anyone got it?
I could send you a working one that no longer has LEDs in it. You could easily move those from your old controller board.
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Old 31 October 2010, 22:48   #8
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hey Jope, that's nice of you, but its not worth the trouble, really. I have several a500. and i just like repairing stuff. if it fails its not a big problem waiting several seconds to reset .

@Merlin
every A500 keyboard has little PCB in the corner, unlike A1200.
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Old 31 October 2010, 23:31   #9
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Ahh, I see. It's been quite some time since I had an A500 in bits.
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Old 04 November 2010, 20:11   #10
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@Merlin

you were right from beginning, it was bad contact on one of keys. so I used liquid silver and some graphite spray; works great now.

thanks.
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Old 04 November 2010, 20:51   #11
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Thought so; a great result!!
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