MA Audio crossover

[S Merlington]

I cant seem to figure this out..

Im getting + - 15 volts on all opamps

Im not getting any audio signal back out of this crossover..

Anyone have any ideas?

 

[Perry Babin]

Do you see audio anywhere in the xo?

Are the meters moving with the audio?

Switches and pots?

 

[S Merlington]

after removing a couple componets i noticed this has alot of water damage to the circuit board..

not sure if its worth the time and money to repair this unit

 

[S Merlington]

Guess the guy wants it fixed .

I removed the components where the water damage was and cleaned the board checked all traces and parts everything tested fine ..

I put all the components back in the board after cleaning it ..

Unit powers up still has no output .. The needles do not move and I cannot find audio in any component in this unit ..

Any ideas where to go from here ?

 

[Perry Babin]

Start at the back of the input RCAs and work your way through the crossover.

 

[S Merlington]

I don't think the supply is working in this unit ..

Should there be +-15 volts on the opamps?

If so then then power supply isn't working I don't have either of the voltages

 

[Perry Babin]

The op-amps have to have some sort of supply voltage. It doesn't have to be ±15v (as you saw in the JBL mono amp) but the op-amps won't operate without supply voltage. The small transformer is likely part of a switching power supply. The most likely faults are the transistors driving the transformer or there is a fault that's not telling the power supply to turn on.

 

[S Merlington]

Back to this unit ..

On every opamp in the unit I get 13 volts on all pins ..

On the negative of the caps I also get 13 volts ..

I'm not getting and negative voltages in this unit..

Any ideas ?

 

[Hexhclass]

maybe open ground trace

 

[Perry Babin]

The information in this thread has been contradictory. You stated that you had supply voltage and then no supply voltage. Is the supply in the amp working?

Did you repair it earlier?

 

[S Merlington]

I figured out the ground issue ..

The supply is still not working in this unit I could never track down the problem ..

I replaced all of the transistors in the supply and checked every component I still have no supply voltage on the opamps .