Phoenix Gold??

[rhempz01]

Found a burnt up resistor and a shorted power supply moafet, sf163a not sure what that is

 

[Perry Babin]

A D prefix means it's a diode. SF163 is a rectifier, not an FET. The FET next to it is likely shorted.

 

[rhempz01]

I don't even know the model I think its a sx2600. Its a 2channel amplifier. These are the power mosfets 60ne, and it uses irf540's for the outputs. It does power up and seems to draw a proper amount of current? The owerner couldn't recall what was wrong with it...... So, it powers up and has audio, after playing for 30 seconds, it makes a strange sound on and off, and draws excessive current. No shorted outputs?

 

[Perry Babin]

Measure the DC voltage across the emitter resistors in each channel to see which channel is the problem.

 

[rhempz01]

Out

 

[Perry Babin]

IT has to be clamped to do as suggested.

 

[rhempz01]

Bias setting again. How do they get turned up?

 

[rhempz01]

One was all the way up and the other at a quarter..?

 

[Perry Babin]

Many times, the owners think that they will get more power by turning them clockwise. When I built amps, I made the bias pots operate in reverse to prevent damage when someone did this.

 

[dukmang]

Genius. Sometimes the thing most in need of fixing is the operator.

 

[rhempz01]

That is very smart perry. Ok so I did get it working I turned them all the way down then about 1/4 turn up. One channel is very louder than the other same. The left channel is very loud the right has a noticeable difference.

 

[rhempz01]

Now I feel nervous testing voltages after the last incident, but I did clean up my work space....

 

[Perry Babin]

The switches in these things have dirty contacts in many cases and can cause an imbalance.