Hey Guys,

I have had an Operation thunder pin for a while now and have been trying to sort out the sound issue that i have. When i first got the Pin i had sound from the Aux board only (speech and half of the sound effects) but no music from the main sound board and the other half of the sound effects that i assume are on the main board.
I first tried reseatting the EPROMS, connectors and ribbons which did not work. i then noticed the sound wire from the main board to the aux board had been suspiciously removed, so i reattached the cable to the connector and fired up the game and was greated with a horrible screaching drone ontop of the Aux sound board sounds i had originally, So i assumed there was a problem on the main board.

I then removed the boards and tested all the traces and connectors which all seemed to buzz out fine except for where some poor repairs on the main board had been done. I had a friend at work whos an electronic engineer have a look at the schematics out for the boards and looked at the problem area, seems some joker had tried to replace a chip on the main board and ruined some of the trace aswell as adding a link wire to the wrong chip, so it was removed , link wire put in to repair the broken traces and buzzed it all out, seemed good now and gave it a test. Sadly, the same horrible drone noise but now seems i have no Aux board sound. GREAT!

Both fuses are fine, the boards boot up and blink as they should and you can just hear some very faint sound though the speakers if you listen really closely.

I had a new set of EPROMS burnt and tried them first before anything else but when i replaced the aux sound board ones, it made it do call-outs repeatidly in a loop at times when playing a game but the sound effects were fine and when i changed the EPROMS on the main board, the boards would not boot.

Im at a bit of a loose end now other than buying 2 new boards, which i dont really want to do because of the expense. Im assuming these are salvagable but not many people i can find in the UK will take on system 3 sound boards for repair and any that will want approx 50 dollars just to look at the board and then about 120 dollars more t fix it if they think they can.

To sum all that lot up...PLEASE HELP...

OK, thanks guys, I think then as it stands since i had reseated all the connectors and tried my new set of EPROMS more times that i can count. I will look into faulty RAM.

Thedefog - when you say 'opamp' are you refering to the aux amplifier where the sound is outputted from the aux sound board?

Also, since my aux soundboard did work before the repairs were done on the main soundboard but not now, is it possible that the auxsound board is still OK but the main soundboard fault prevents the Aux sound board from working correctly or is it a case of if the aux sound board is working, it will work regardless of any issues on the main sound board?