I have a Sorcerer that was playing all of it's sounds fine when I first picked her up. I started a post last month on trying to fix the flippers but thought this issue needed it's own topic. Here's a recap of the end of that thread: While trying to fix the flippers last month over the course of a couple of days the sound started to cut out and I started getting an error code 7 on the cpu. It was suggested that I twist the IC sockets after a couple of games and see if one of them locks up the game. I played a bunch of games and then twisted them all and the game locked up. Realizing I should have tried them 1 at a time I tried them again and found that U5 locked the game up. 1st I replaced U5's 6821 pia and game worked fine for a day then next day had an error code of 7 again. This time when I manipulated the U49 sound rom the game went back to a "0" diagnostic so I ordered a new set of game roms and re socketed and replaced U49. I also re socketed U19 and U20 game roms and added the new chips in them as well. Still the next day after playing fine with all sounds the game wouldn't boot with an error code 7 again.
I tried manipulating the sockets again and found U17 a 6808 brought the game back. I replaced the socket and found another 6808 and that fixed the error 7 code but the game didn't have sounds. I can't remember where I read it pinwiki or another pinside thread but it was suggested to swap the 6808 chips at U17 and U13. When I swapped them the 6808 that was by the sound section in U13 now locks the game up when its in U17's socket. I was out of 6808's but read that a 6802 was a drop in replacement and only needed to be jumpered if you were using the chip's internal ram. I placed the 6802 in U17 and now the game plays for days without locking up and I have clear speech but all other sounds are super low. In a game or in test mode through the door or the SW2 diagnostic on the board, you have to put your ear up to the speaker to barely hear them.
The cabinet pot works fine. I can hear the static change smoothly when I turn the knob. The dmm test with one lead on the middle lug and testing the other lugs while turning the knob reads smooth changing #s. I re crimped the wires running from the pot to IJ15 just in case with no luck. The pot on the speech board works fine as well. I then read to isolate the cpu from the speech board to test just the sounds by removing the ribbon connector between the 2 and place a jumper on W10 under the U12 6810 ram chip. When I test the sounds with this scenario they sound the same, super low.
I've tested the 5 pin 2002 audio amplifier at U47 by finding 13 volts on pin 5 and pin one produces a hum. I have tested the R77 resistor for the -12 volts and pin 3 on U48 has the -12 voltage as well. I have tested the Q51 transistor and have the same reading as all the others on the board 650 ohms on one leg and 900 on the other. I have tested pins 2 through 9 on the U13 6808 chip and they pulse from 0 to 4.85 volts when each sound is produced for that pin. I also read in another thread a pinsider solved his issue by replacing U12's 6810 ram chip. I re socketed and replaced that chip as well with the same results. Both the cpu board and the power supply board don't have any cracked solder joints especially at IJ15 and 17 and the 15 pin connector on the psb.
I removed the board to test the caps. C2 measures 600 ohms one way and the C7 cap is 650ohms with the leads reversed. C5 measures 280 ohms and 340 ohms, C24 under the U47 amplifier measure 1 and 1 but when I measure the positive lead traced to R73 I get a measurement of 278ohms. The last cap C53 measures 1.400ohms and 716 ohms.
The last component that I don't know how to test that I've read in other threads is the oscillator at U21. Any other advice on what I missed or which component I should suspect would be greatly appreciated.