power bass

[timwebb]

ok so i rebuilt the driver card and it powered up good for a few minutes.then these two resistors smoked between q110 and q11.

[Perry Babin]

Were the output transistors in the circuit?

[timwebb]

no all transistors were out.

[Perry Babin]

That may have been the problem. With the outputs out of the circuit, the transistors connected to those resistors were likely driven on hard to compensate for DC on the output terminals (could have been only millivolts). That could have caused the resistors to overheat.

[timwebb]

i just replaced all the transistors on the board. im trying to save transistors cause they exploded the last time i put some in.

[Perry Babin]

Were you using a current limiter when they exploded?

Which ones exploded?

[timwebb]

i used a 10amp fuse.and the output transistors keep popping. im not seeing a wave on any of the gate resistors for the out puts.

[Perry Babin]

This is a self oscillating amp. You won't see any oscillation with the outputs out of the circuit.

Do you have a large 2 ohm current limiting resistor?

[timwebb]

no i dont have any on hand.

[Perry Babin]

Either buy a 2 ohm 100 watt tubular ceramic resistor (~$10) from digikey or mouser or go to Radio Shack and buy four of the 8 ohm 20 watt resistors and wire them in parallel to make a 2 ohm resistor. A current limiter won't save parts in all instances but they will easily pay for themselves in just a few repairs.