OP

Quoted from Tbirdmatt66SS:

Hello.
On space shuttle , U48, the DAC chip. Pin 3 receives and passes through the -12v as it continues to 1J20 pin 2. Here’s the conundrum... with the -12v disconnected at 1J17, and the rest of the board powered on the bench. I get positive 4.3 volts on the -12 v circuit at all points of it. If I take U48 out of its socket, the voltage goes away. Before anyone says u48 is bad, I had already replaced it. So what could have caused it to go bad , or is something coming into U48 from the PIA, which is new and corrupting U48.
Thanks for any assistance.
Matt