general amp voltage question?

[safeshow]

I am working on a c-300 chiro audio amp, I noticed one of the channels made a really loud strange noise from the speaker (like a cap discharging),, I turned it off asap, I put a meter on the rail voltage on the output pcb + an - ,,,, Im pretty sure I was missing the - voltage,,, I pushed on the pcb an it came back, dont know for sure if my meter connection was bad or what,,,, just wondering what would be the effect if I was missing a - rail voltage to the outputs (in general)

 

[sgrossklass]

Results are going to vary, but the amp definitely wouldn't be working. Looks like you 'll have to look out for bad solder joints and hairline cracks in the board, as well as corroded traces (watch out for the black "killer glue" as well, if any).

 

[rayma]

The reading was probably a probe problem. Always attach the probes when the circuit is unpowered,
and then switch on the power. Measure both rails, and if one is actually missing, look for blown fuses.

 

[Douglas Blake]

I am working on a c-300 chiro audio amp, I noticed one of the channels made a really loud strange noise from the speaker (like a cap discharging),, I turned it off asap, I put a meter on the rail voltage on the output pcb + an - ,,,, Im pretty sure I was missing the - voltage,,, I pushed on the pcb an it came back, dont know for sure if my meter connection was bad or what,,,, just wondering what would be the effect if I was missing a - rail voltage to the outputs (in general)

Disconnect all inputs and speakers ... put your meter on the speaker connectors and take a reading ... I'm betting you will find a very large DC voltage on one of them. From you're description you've blown an output transistor.

 

[oiphy]

I am working on a c-300 chiro audio amp, I noticed one of the channels made a really loud strange noise from the speaker (like a cap discharging),, I turned it off asap, I put a meter on the rail voltage on the output pcb + an - ,,,, Im pretty sure I was missing the - voltage,,, I pushed on the pcb an it came back, dont know for sure if my meter connection was bad or what,,,, just wondering what would be the effect if I was to the outputs (in general)

missing a - rail voltage will prolly give you a big fat + dc out