Re: Asteroids PCB repair help

Following up more.

On Nov 9, 2012, at 10:53 PM, Ian Eure wrote:

> Been busy with other projects, circling back to this stuff.
>
> On Aug 19, 2012, at 5:03 PM, Rodger Boots wrote:
>
>>
>>> PCB #1 (rev 02), the board that came in my Asteroids: No clock. Replaced Y1 crystal, LS04 at B5, no change. Traced the lack of clock to a failed pullup resistor R29. Board will now boot and play for a few minutes, then start drawing scrambled vectors and reset. Appears to be the watchdog, since I see RST on the CPU activating. Test mode is the same. I'm not sure how to approach this one. Vector timer?
>> Make sure processor is a 6502A.
>>
> It is a 6502A.
>
>
>> Make sure +5 is right AT GAME BOARD.
>>
> It's correct, reading just over 5v on the far side of the PCB.
>
>
>> If still bad, cool EPROMS/PROMS one at a time to see if one is heat sensitive.
>>
> Will report back. I let it run for 5-10m and the problem didn't recur, so I don't know. I'll just let it go for a few hours when I have more time.
>
I cooled off the PROMs, and the game stabilized. I pulled them all, cleaned legs, reseated, and the board appears to be stable now. I ran it for a couple hours and racked up some high scores with nary a sign of resetting.

Haven't worked on the other two boards any more yet.
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Received on Sun Nov 11 19:50:51 2012