If the rom sockets are original, then you should replace them. The symptoms you describe indicate bad sockets. When I repair an early WMS, I slap the back of the backbox and tap on the boards. The game should not lock up. If it does, then it's new sockets all around. After that it always passes the abuse test. The 40-pin interboard connectors fail too, but it looks like they are new in the picture you provided.

I saw your post, but I didn't want to give you bad advice and make things worse. It's been awhile since I worked on a Williams System 3-7 board. I thought surely someone more capable would help you.

*edit* Nevermind, I see where you said you did reflow the solder on the connector pins. My fault for not reading closer.*/edit*

Replacing the rotten Scanbe sockets is usually a good idea. Some people say the pads and traces for them are too delicate, but I've never had a problem.

Even if the sockets and cold solder joints aren't the issue, it's good to eliminate them first before getting into the heavier troubleshooting with test ROMs and logic probes.

4.8v on the power is normal with current load. So don't touch that. Also, regarding the sockets, don't bother replacing them unless they are scanbe or falling apart or you'll probably cause more trouble than you'll solve. You can probe continuity and inspect the pins on the socket to see if they're in good shape. If it is one of those sockets where you cannot easily probe/see the pins, replace it.

If you can just pull ICs right out of the socket without much effort, then your socket is probably worn out. As to whether it's a Scanbe or not, the name is stamped on the socket body itself. They look like this:

scanbesockets.jpg

One reason they're notoriously failure prone is the weird way they grab the pin legs. Instead of gripping it across the flat edges of the pin, it grips the side of the pin.

The top three empty sockets on your MPU board don't seem to be Scanbe sockets, since they're open body sockets.

That socket doesn't appear bad, but if it does not grip the IC well or it feels loose, replace it. Otherwise don't, you'll just risk damage.

no prob. anytime.

Most the time, it is thankless, so thank you for recognizing that.

Wouldn't hurt to redo all connectors if volts drop when jiggling connectors. The original are round pins and new style are square so better connection

Honestly it sounds like you may have two problems. A weak power supply and the MPU is locked up probably do to bad physical connections. I see the two LEDs lit up solid on the MPU. It has at least close to 5v to make the LEDs light up.

10.5v is flirting with the breakdown voltage of the LM323K. Add a current spike from flippers or solenoids and i could see the 5v dropping out.

Low unregulated voltage is a lot of times an indication of a failing filter capacitor. Set your meter for AC voltage, lowest voltage setting. Read across that test point and ground. If you see more than 0.25 VAC the filter cap can be considered failed.

I can repair and bulletproof your boards. I have rebuilt hundreds of these board sets, I am very proficient in repairing anything wrong with them. I will install all new header pins. New interconnect. New filter caps. New IC sockets. New 5w lamp column resistors. Clean the board front and back. 1 year warranty. I always recommend having the MPU and driver board serviced at the same time as they are interconnected.

MPU $50 ($60 with no battery NVRAM)
Driver $50
PSU $40
Sound and Speech $45

Thanks
Andrew

23.0vac is an incorrect reading from you DMM. Some meters have trouble taking a low AC voltage reading. You could try using a resistor inline with one of your meter leads if that is the reading it is giving you.

0.23vac would be in range, but close to what a problem amount of ripple. When i put a fresh cap in the ripple on the 12v line is usually less than 0.1vac.

I think what is going is you want to add a small bit of load, 10k or so in line should do it, i dont think will matter much, just dont go too low in resistance, like under 1k. That is a low end DMM and for whatever reason i have seen them give the bad readings on really low AC volts, not sure why. Inline resistor should make it give a correct read by introducing some kind of load.

That DMM will do the minimum for you. Depending on how deep you want to get, consider a better DMM. For a low end but highly functional meter i recommend the mastech MS8268.

Ouch that guy got burned by Leon's memory test pretty bad. I bet if he would have used the memory test built into the green flipper roms would have declared them bad.

I will send you a PM.

I repaired Robert's boards today.

I did my standard rebuild of the boards and it was still locked up. Clock was good, reset was good, address and data lines where good. I looked at the PIA outputs and many legs sitting highish around 3v. It was pretty obvious the PIA was bad at this point. Replaced the PIA (AMI BRAND of course) and the MPU came alive.

There was some solenoid driver problems and the 7408 for lamp column 1 had a floating output which made all the lamps in column one light up randomly and bright.

Scrubbed the boards clean and It is burn in testing in my TimeWarp now and will be ready to ship back Monday. It is getting one my nifty 5101 adapters, so no battery worries ever again.

Nice example!
-mof