Reply 400 of 495, by TubeTimeUS
appiah4 wrote on 2020-07-10, 21:19:There is certainly +5V and -12V elsewhere on the card, I can measure them on Pin 4 and Pin 11 of U11, for example. However, there is still no +5V on Pin 14 of U12. There is +5V on the +5V side of R38, but the side that is connected to Pin14 shows no voltage, it is shorted. When I remove the DAC at U12, I can measure +5V at Pin 14 of the socket.
Could be pins 14 and 15 got shorted somehow, you could measure continuity of the socket. Take out the DAC and measure the resistance between pin 14 and pin 15 on the IC as well, and between pin 14 and pin 2. If the chip has a short then it's bad. If the chip was ever installed backwards, it's bad.
You might also have a power supply that is going bad. Check the capacitors for evidence of leaking electrolyte, and measure the ripple voltage on each supply voltage rail. You can do this with a multimeter set to AC volts.
Also check your Snark Barker for any electrolytic capacitors that are in the wrong way around. If there are any that were in backwards, they need to be discarded and replaced.