well this means that you have a problem in the input circuit of the board. this includes the connector, the 4050 buffer (IC5) and the PIA.

did you mean that when grounding the input pins you had sounds and then it stopped working after a while ?

Except whoever the OP sent the board to said it was working fine. So I would assume that person would have also tested the input circuitry...

viperrwk

if the problem is intermittent he may have missed it. it happened to me not so long ago (a board coming back not working any better)... that is why I learned how to repair it myself with the help of Clay's repair guide.

yes. connector 10J3 on the sound board and connector 2J9 on the Driver board. Connector 2J9 also connects to the Flash lamps, the knocker and the coin lockout solenoid. But if you have sounds by grounding the input pins and then nothing then you have for sure a problem on the sound board.

if you have no sound at all grounding the input pins and the test button is working then it means that you have a working CPU, working amplifier and at least a semi working PIA but probably some problem in the input circuit.
It is indeed strange that a professional did not at least test the inputs... just running the test loop for 2h is not enough...

You'd expect that.

You could run the diag loop yourself all day long...

The board was here and it was tested to be working by grounding the pins. Everything tested ok. I let the board run for a hour. I even flexed the board to see if it would quit. There was a socket for the PIA and the chip was installed and it was good and tight!

Where are you connecting your ground wire for testing?

now we know that the sound board is ok so we can move up from there. first test the cable with a DMM. The cable goes from 2J9 (Driver) to 10J3 (sound board). The 2J9 connector on the Driver board also connects to the Coin lockout, the Flash lamps (FIRE POWER) and the knocker. Do you have issues with any those ?

Grounding the sound transistor tabs will proove the wiring / connectors. I recommended this way early on in the post. Do no think the OP ever tried that.

Based on everything i have read in here it is likely to be a connector problem.

Agreed. Seems like OP is super excited to get his game running and is skipping some troubleshooting steps. I think we all know how easily that can happen. Unless its just me, I would bet many of us were SURE the problem was "here" when it was "there" all along.

Go slower OP and your repair will go faster!

Try reflowing the header pins. They are always cracked. I had the same issue on my FP.

Guys, Chime in if I'm wrong here.

OP, Before you follow my instructions in this post, I'd like confirmation from the other guys here. Just to be sure.

Put your old driver board back in and test again. If it works, then you have some sort of connector issue: Bad crimp, cold solder joint, etc. and the issue will probably pop up again soon.

If it doesnt work, then it still could be a connector issue, but we can run some tests to eliminate that.

Look at the attached PDF. It shows in great detail the driver board. Look at connector 2J9 in the bottom left corner. Notice that 5 of the pins are for sound; 1, 2, 3, 7, and 9. The bank of transistors just to the right of that connector are where we need to look next. With the machine on, attach one end of a test lead to the threaded stud in front of the opening at the bottom of the backbox. Carefully and briefly, touch the other end of the test lead to the metal tab of the following transistors. The numbers are screen printed on the circuit board. Q33, Q31, Q39, Q37, and Q35.

If you do this right, each time you touch one of these transistor tabs, a sound should be triggered. If you hear a sound, you have verified the connection from that transistor, through the connector on the driver board, through the wire harness, through the connector on the audio board, to the working components on the audio board. You can be confident in the wiring and connections at this point. If you do not hear a sound, you most likely have a problem at connector 2J9. Bad wire connection in the IDC connector or a cracked/cold solder joint on the header pin.

Try this and let us know how it turns out. Be as specific as I have been in your description of the results so we can all be clear and on the same page.

This test does not tell us if the driver transistor is good or bad yet. We will move on to that next if need be.

Sorry, forgot to attach the PDF. Here it is.

If it works with another driver board then you most likely have something bad on the Driver board. I find it hard to believe that all transistors (Q30 to Q45) connected to 2J9 went bad all at once but they can be easily tested so do it if you have a DMM or use Pafasa's indications. However all those transistors are connected to the PIA through IC3 and IC4 (N7408) so maybe one or both went bad. After that there is only the PIA left.

Here I would pull out the boards from the machine and test them on the bench with Andre's or Leon's test ROM.

Good Point. How do you test the N7408 chips? Diode test?

Here is a quote from Clay's guide:

These chips can also be tested with a DMM set to the diode function and the game
off. For a 7408, put the red lead on ground (pin 7), and put the black lead on pins
1,2,3, 4,5,6, 8,9,10, 11,12,13. A reading of of .4 to .6 should be seen for each pin
(a reading lower than .2 is a big sign of a bad chip).

Is this guide available somewhere? I dont see it on the pinrepair site. Is this one of the books Clay took down a while back?

I don't know the copyright status of those repair guides but if you google 'williams system 7 repair guide' you'll find them.

cool thanks!

http://thepiratebay.se/torrent/6337010/pinrepair.com_Pinball_Machine_Repair_Guides___And_other_misc_Pin

I just repaired one for a customer with the exact same issue and ended up replacing the 6821 on the sound board.