Hello my name is Jos van der Sterren and I live in Holland and a total newbie.
I have some technical background but that is related to cars.
Always been crazy off Pinball machines so I got a broken Williams High Speed.
First off all the battery holder had some damage of alkaline leakage and I cleaned it.
The Mpu won't boot no digital number on the matrix.
I did some research on the net and tested the 5 volt and that was good but to be sure I bench tested it with a good PC Psu.
I rebuild the reset line with a reset generator and put a new microprocessor U15 and a new Ram U25 6116 on the board.
Also The gamerom U26 and U27 are new.
When I fire it up a have a low signal for a moment and then a constant high with the probe on the reset line but no boot.
But the strange thing is dat when I short the gnd with the reset line its boot and the matrix shows a 7
So now I am confused.
What am I missing?
So that's why I need some help from the experts.
Can someone help me?
Thanks!
Greetings Jos

Hello Chris,
You see i am learning so when there is a digit in the matrix doesn't mean its booting.
I give you 2 images.
The one before and how its now.
Thanks already for your help.

20220424_144037 (resized).jpg

20220822_151310 (resized).jpg

Thank you Chris.
I will test it and come back to you with the results.

There is more corrosion on some components so i wil deal with this first.
Thanks for the help so far.
I wil be back for a update.

After i cleaned everything some components still malefunction.
So i decided to replace the Mpu and bought a Rottendog.
After installing the machine works like a charm.
Now only the ball in game display isn't working.
So a new project is coming up.
Thanks for the help everyone.