TECH: Robotron

[zepromz]

[ukvac] TECH: Robotron
My Robotron PCB is ill
Played fine for ages, started giving odd flashes of vertical "jailbar"
effect, then crashed/froze. I rebooted it, and its not even getting to
the rug test, just light blue vertical bars. Any ideas, Chad/Dave maybe?

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[Dave2084]

Re: [ukvac] TECH: Robotron
At 00:30 16 12 00, you wrote:
>Played fine for ages, started giving odd flashes of vertical "jailbar"
>effect, then crashed/froze. I rebooted it, and its not even getting to
>the rug test, just light blue vertical bars. Any ideas, Chad/Dave maybe?

You getting any error codes of the ROM board?

Standard Reflex actions for any totally dead Williams is:

1. Check you're getting +5v, -5v and +12v AT THE 4116 RAM CHIPS
PSU Problem most likely ...

2. Check you've got signals on the address and data lines of the RAM chips
74153 problem as a rule ....

3. Check all the signals generated by the clock cct.
lots of 7474's here and a 74107, these ARE prone to failure.

4. Check the ribbon is OK ... I've started getting an alarmingly high
number of bad ribbons recently and the 40 offset (4x 10 way) ribbon head is
not easy to find!

If you have another ROM board (not Defender though) try it to rule that
out, though its most likely the CPU. Stargate, Joust and Sinistar (Splat!
if you have one!) will also work .

Let me know how you get on ....

Dave Langley
Williams Documents + More On-line @ www.robotron-2084.co.uk

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