Just picked up a Space shuttle to add to my collection. At the price i picked it up at i figured there would be some issues. After a couple hours I think I have all the parts I need ordered except one.

When i was doing a sound test the system steps through all the basic sounds correctly. When i hit the sound test button on the main board to trigger the voice test the volume is very low. The balance knob on the speech module is turned all the way up, turning it in the opposite direction lowers the faint voice till it goes away. Im not sure what might be wrong. The voice prompts are spread across the eproms on the speech board and U49 on the Main board, making me think the problem lies with the amplifier (maybe).

Just not sure where to start on this one. Since the basic sounds are loud, i would think the amp is fine. The balance knob on he speech board makes me think the two sound sources (basic and voice) are combined on the speech board then sent for amplification. I cant find a schematic on the speech board so any help troubleshooting would be appreciated

I think the pot is ok because i can control the volume of the sound coming from the main board. There are 2 dual op-amps on that board, they were cheep so I am going to replace them. I hope its not the 3417 slope delta module because they are hard to find.

the op amp fixed the issue. Not sure what one it was because i replaced both of them. Sound is loud and clear now.