American Bass 500.1

[caraudioguy2100]

With the muting transistor in circuit I get
-0.04

With it out of circuit I get
5.01 volts

 

[Perry Babin]

What's the resistance from the base to the emitter of that transistor?

 

[caraudioguy2100]

OL

 

[Perry Babin]

Is R57 (connected to the base of the muting transistor) within tolerance?

 

[caraudioguy2100]

It measures 99.4K ohms out of circuit

 

[Perry Babin]

Was the meter on ohms (not diode-check)?

Try measuring the voltage across the B-E again after the amp is on for about 10 seconds.

 

[caraudioguy2100]

With the muting transistor in or out of circuit ?

And the meter was set to ohms

 

[Perry Babin]

Measure both. It takes only a few seconds to remove/install the transistor.

 

[caraudioguy2100]

With it out of circuit I get 5.19

With it in circuit 0.57

 

[Perry Babin]

Is the protect LED lit?

Is Q51 shorted or leaky?

 

[caraudioguy2100]

No protect light

Q51 is shorted

I will put a new one in and measure from base to emitter on the 1303

 

[caraudioguy2100]

With a new 1381 Q51

I get 0.00 volts from base to emitter on the muting transistor

 

[Perry Babin]

That means that the muting transistor would be off.

 

[caraudioguy2100]

So I will replace the outputs and driver ic’s again and see what I come up with

 

[Perry Babin]

Is the driver board still out of the amp?

 

[caraudioguy2100]

The driverboard was in the amp I just used a jumper in Q10