Ciao to everybody!
I've a problem with a Williams system 3-7 driver board. It has good conditions and I reflow all the connector solder joints, new resistor for the lamp matrix, some TIP102 for solenoids and a new interboard connector... all seems fine once connected to the CPU.
In fact the test (Leon's rom) doesn't start, both LEDs are lit and remain lit, the CPU is blocked and I cannot test the PIA and all the driver IC. I can't do anything
(of course with another driver board the test is ok, so it means the problem is in THAT specific driver board).
Where I can take a look trying to solve this problem?
Thanks in advance

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New pics as requested..
It's the first time that I've a similar trouble. In every case I was always able to boot the board in test..
Do you think is a short or bridge between pads? With multimeter here is ok..
Could a bad IC or PIA avoid the booting?
Thanks again
Ciao
Loris

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Thanks Andrew for your intervention. So you are telling me that AMI PIAs are awful and must be changed...
From web guides or your helpinf topics I learned to test PIAs and ICs in test mode with Leon eeprom. In this case I cannot for the matter I've just explained. Is there a method to test at the bench this PIAs or TTL chips without the "shoot in the dark" way?
Sometimes in my repairs, the driver boots even a PIA (for example) is missing... so I'm asking to you why...
Have you some suggestion to follow in order to repair this board?
I have to try to pull out and change the first solenoids PIA and try again...

Hi everybody! Thanks again for your support, especially Andrew for its inputs and suggestions!
PROBLEM SOLVED! It was the lamp PIA... once changed, the board passes successfully the test! I also changed the two remaining PIAs in order to "bulletproof" the board!
Thanks!
Ciao
Loris

I take note of this hint!!! You're my mentor!