It could also be a bad memory chip the batteries power and keep alive .. something I have not heard mentioned. I think this is U25 on that machine. It could be flaky.

If it's like alot of the Williams I have worked on it's a 5101 RAM IC. These are getting hard to find (obsolete) and go bad alot. You can still find them at places like Jameco Electronics. I bought a dozen myself last time.

Here is a link: Most of these are pulls off of old boards anymore.

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_42198_-1

Quote: "That is a good point Twizz. Don't discount yourself. Could be any of these problems, or none of them. "

Exactly .. we make intelligent guesses. But if you are gonna collect older Williams machines get a few 5101 RAM IC's while you still can.

They are used in all the older Williams SS machines (system 3-7) to store high scores, system settings, etc ... the batteries keep it powered. It's an old obsolete memory chip that hasn't been made in over 20 years or more. So finding them is getting more difficult. I have some brand new ones but can only find used "pulls" anymore where they take them off old PCB's.

Go here and scroll down to section 3a for more info:

http://www.pinrepair.com/sys37/index2.htm

I believe they are also used in Gottlieb System 80 machines as well. Also Bally machines like Star Trek. Just a good thing to have a few of if you collect machines.

Help me out here others ... did I miss any ??

I don't think so donjagra (only systems 3-7 Williams)
Here is the part number various manufacturers used for it:

# Williams: 5A-9017
# Bally: E-00620-0042
# Gottlieb: XO356

It is U25 on that machine but look above for info on that. It's Toshiba TC5517 and even harder to find. I think I've heard of people using a 6116 in it's place. It rarely goes bad.