Well after over two years of on/off renovating my TZ, today was a turning point. The cab and back box were back together again and I'm really happy with the way it all looks. This is my first pinball reno experience so it was a big moment. The top of the pf has completely stripped, all solenoids rebuilt, cab repaired and redecaled, back box emptied and also renovated and re-decaled, so I was a bit nervous. Mostly it was good news when I turned on with the majority of systems working and no black smoke, however I don't have any sound now, just a bit of hum/static.
The sound was working before I took everything apart but there have been a couple of changes. The audio card had been hacked so I did some work to try and get things back to normal. The hack that I undid was that the original owner had replaced IC U2 with a potentiometer and lifted W9. I reinstalled U2 (IC MC3340) replaced W9 and got rid of the pot.
When I turn on, the only sound is click followed by a continuous low hum/static that doesn't get louder when I adjust the volume using the buttons on the door. I don't get any boing when I turn on. The message I get from the test reporting is "Sound board Interface Error".
There is another factor that may or may not be affecting things. Over the couple of years that the back box has been stored (without translight in place), silverfish have eaten the paper stickers that cover the glass windows on the audio eproms U14 and U15. I don't know how long the eproms were exposed but despite having been in a mostly dimly lit shed I guess it's possible that the eproms may have been corrupted or erased.
Things I've tried:
Checked audio card fuses. both ok
The cable from the cpu board is new but I tried reseating all connectors on the ribbon and also tried reinstalling the old cable, neither made any difference. I also tried reseating all audio card connectors and pushing down all the wires into the connectors
I followed Clay's suggestion of removing the 3 eproms and turning on, then replacing them one by one. None of that made any difference to the sound.. all gave same hum/static... no boing noises.
I checked the supply voltage on U2 which was about 9.2v so within the operating range of the attenuator.
I tried removing U2 and the static/hum was silenced. Unfortunately I broke some of the legs on U2 trying to reinstall it so I have to get another one now (cheap part).
Anyone got any ideas how I should proceed? Is it possible that the eproms are stuffed or does the lack of any boing point to another problem... should I get a boing when the eproms are removed?
All help welcomed!
