All electronics fixed, but still problems…

The mailwoman came with goodies this morning; four 3081 chips! So I put them in the CPU board and ran Leon’s test EPROM again. Victory!

Two new 3081's

So I mounted the board back into the pinball machine, connected everything and switched it on. Not so good… The sound was weird, only a few cracks and screeches would come out of the speaker.

I disconnected the sound board from the CPU board and ran the test and all went well, so clearly there was a problem with the communication between the CPU board and the sound board. I checked the schematics and the only thing that could be wrong was the entry stage behind CN7.

Using my multimeter I immediately found that all the data lines where shorted to the +5V. So only the resistor array ICR6 or the 74LS244 could be the cause. So I started with desoldering the resistor array, but that wasn’t the problem. So I desoldered the 244 and found the culprit!

Off to the store I went. Bought a couple of BF422’s and a 4042 as well for the two display driver boards that needed them and even went round to the hardware store to get some screws, there’s a lot of screws missing in the cabinet and head.

Back home, I put all the components where they should be and succes! I have sound!

A new 74LS244

The two display driver boards got their components too and now I have 4 working displays.

A new 4042.

Two new BF422's

Four working displays, one to go...

Next week my ZM1550’s should arive and then I can fix the last display.

And that’s it for the electronics… OR IS IT???

The game still won’t start. No flickering lights, no sound, no highscore showing, nothing… just all 0’s on the displays and that’s it.

When I put DIP switch 4 in PRGM mode, the soundboard now makes the annoying warning sound and I can do all the tests, reset the accounting and set all the options. So I set the options, resetting the ones that already had a good value, clear the accounting and do the tests. All tests are fine. The displays do their thing, the lights go on and off, the solenoids scare me and the sounds are played in order. But then there’s the button test (test #2) that just shows 18. And whatever button I press, it doesn’t change. I guess I’ll have to go through the wire harness and measure what signals I do get.

Guess that’s my queue to end this article and get back to work!

 



Leave a Reply