Williams P.S. Boards - Upgrade / Repair Questions

Hello All !

I've begun to install Bob Roberts' Williams PS repair kits (parts &
connectors). I've managed to make a working board (works but resets my
Joust after 10 minutes or so) non-working. Replaced all the caps, the 7905
& 732 regs, the 2N6057 & 2N3055 (not shorted).

All the LEDs come on. Game won't even boot up now. I've taken voltage
measurements but don't have the numbers available to put into this e-mail -
they were all present but low. I could give the exact measurements later
if this helps. Here's my questions:

1. Are there any other commonly failing parts on these boards I should
consider replacing?

2. Do R14, R15 & R6 (The 5W resistors) usually need replacing too? They
all seem to be way out of (5%) tolerance. In the circuit the 2 ohm
measures out at 3 ohms. The .12 ohm measures out at 10.8 ohms and the .27
ohm measures out at 11.9 ohms.

3. Is there a good FAQ or other document(s) regarding Williams power supply
problems, symptoms and diagnostics procedures somewhere you can point me to ?

4. I've got probably 20 or so 4116 RAMs in a tube somewhere, do you think
they've really blown or is the RAM errors from the low TTL voltage from the
power supply ?
 
Another PS board in my Defender made it through the upgrading and worked
fine for a few days of playing. It now gives me a RAM error in both Joust
(locks up with RAM error screen) and Defender (plays but with garbage on
the screen, resets shortly after).

I really want to be able to keep my Williams games original and I'm not
interested in installing new switching power supplys. I do however, have
one of Bob Roberts' new switching power supplys that haven't been installed
in any game yet. Maybe I'll use it for testing purposes to ensure that the
RAMs are OK. I have a Joust 2 that seems to have a good working power
supply in it. Maybe I should use it for testing purposes.

Whadda ya think ? Am I way out of line here ? Any suggestions or guidance
would be much appreciated because I still have a couple cocktail tables & a
couple more uprights to do this upgrading work to.

Thanks !

Steve Winslow

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Received on Sun Oct 29 09:42:18 2000