Kenwood KAC-7204

[mike49504]

Amp powers up and draws excessive current . None of the fets or outputs test bad in the board Im gonna pull the outputs out and see if any are leaking. I will update in a few

 

[mike49504]

With outputs removed amp powers up and idle's perfect. None of the outputs test shorted and no leakage. Any ideas on where to go from here?

 

[Perry Babin]

Check for broken solder connections on the bias transistors.

 

[mike49504]

Ok the problem is in the right channel. I reflowed the solder on the transistor (C3114) that connects to the bias pot and still draws excessive current.

 

[Perry Babin]

Did you try reducing the bias?

 

[mike49504]

Yes both Bias pots are fully counter clockwise.

 

[Perry Babin]

Measure the DC voltage across each of the 4 emitter resistors. Post the voltage across each one (to 3 decimal places).

 

[mike49504]

1:0.04 volts

2:0.04 volts

3:0.04 volts

4:0.04 volts

 

[Perry Babin]

If the voltage between the base and emitter of the bias transistor is 0v, check the driver transistors. If none appear shorted, pull them and carefully check for leakage.

 

[mike49504]

Between emitter and base on the Bias transistor i have 0.51 volts.

 

[mike49504]

Replaced the drivers and amp powers up and idles perfect. Thanks Again Perry.

 

[Perry Babin]

What if you turn the bias pot the other direction?

If that doesn't reduce the current, short the bias transistor base to emitter.