Williams P.S. Boards - Upgrade / Repair Questions

HI Gents!

Thanks Chris & John for the responses. I just took measurements off of two
different boards that I have worked on. Both boards were tested in my
Defender upright. Here are the numbers:

Board #1 (Currently gives RAM error - will play but resets after a moment.
 A dotted line runs across the top of the screen.)

Connector 4J2 Pin # Expected Measured
                        1 -5V -5V
                        2 KEY
                        3 +12V Reg +11.55V
                        4 -12V Reg -14.78V
                        5 +12V Unreg +12.5V
                        6 +12V Unreg +12.5V
                        7-11 GND
                        12 +5V +5.1V
                        13 +5V +5.1V
                        14 +5V +5.1V
                        15 +5V +5.1V

Connector 4J3 1 6.3VAC 4.78VAC
                        2 6.3VAC 5.15VAC
                        3 27V Unreg 20.7V
                        4 N/C
                        5 KEY
                        6 GND

Board #2 Had symptoms as board #1 and nearly the same measurements as above
with the following exceptions found on connector 4J3.

Connector 4J3 1 6.3VAC 4.8V
                        2 6.3VAC 4.9V
                        3 27V Unreg 20.7V
                        4 N/C
                        5 KEY
                        6 GND

Connector 4J1 from the Transformer in Defender measured out as follows:

                        1 GND (BLK wire)
                        2 N/C
                        3 21.9VAC
                        4 N/C
                        5 10.8VAC
                        6 N/C
                        7 KEY
                        8 64.4VAC
                        9 45.2VAC
                        10 N/C
                        11 42.2VAC
                        12 35VAC

Chris, my schematic doesn't specify what the voltage should be at specific
points in the circuit. I would really like to get my hands on those. It
doesn't even mention what should be found at the couple different test
points on the board. Whaddya think ?

Thanks again for all your help !

Steve

At 03:00 PM 10/29/00 - 0500, you wrote:
>Steve,
>
> I was just working on one of these last night as a matter of fact. Which
>readings are low and what are they? Your best place to start
>troubleshooting is with a set of schematics. The set I have gives the
>expected voltages at different points along the circuit so you can find
>where things start to go bad. If you don't have these, let me know and I
>can scan the appropriate images in and send them to you.
>
>Thanks,
>-Chris
>
>-----Original Message-----
>From: Steven Winslow
>To: rasterlist@synthcom.com
>Sent: 10/29/00 12:18 PM
>Subject: RASTER: 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 Wed Nov 01 17:33:56 2000