Kenwood KAC-7202

[S Merlington]

This amp doesnt power up..

Heres what i have on the 494

Pin 1:2.56
Pin 2:0.53
Pin 3:4.59
Pin 4:0.32
Pin 5:1.48
Pin 6:3.62
Pin 7:0
Pin 8:13.88
Pin 9:0
Pin 10:0
Pin 11:13.88
Pin 12:13.88
Pin 13:4.95
Pin 14:4.95
Pin 15:4.95
Pin 16:0

Any thoughts?

 

[Perry Babin]

Remove Q610. Does that allow the amp to power up?

Be careful. This will defeat most of the protection circuits.

 

[S Merlington]

The power light will come on red for half a sec then goes out amp still wont power up with Q610 removed

 

[Perry Babin]

Desolder one leg of D613.

 

[S Merlington]

Do you happen to know the value of R343 its badly burnt

 

[Perry Babin]

4.7 ohms.

 

[S Merlington]

Ok i replaced it and replaced 1 A965 driver that was defective..

Tripple checked the outputs out of the board and all of them test fine..

with the outputs in the amp it will draw excessive current ..

If i remove them amp powers up and idles fine..

It doesnt matter what channel the outputs are in when it draws current..

Any ideas what to check next?

 

[Perry Babin]

In a lot of the older kenwood amps, the bias transistors would develop bad solder connections and cause the amp to draw excessive current.

 

[S Merlington]

Took them out of the board cleaned the pads and resolderd them back in ..

Amp still draws 40 + amps of current..

 

[Perry Babin]

Have you tried setting the bias pots fully CW or CCW? Sometimes they're designed to be adjusted from the bottom of the board so I don't know which way is down.

 

[S Merlington]

I set them to what i think is CCW but i will turn them the other way to see if it helps

 

[S Merlington]

You were right i adjusted them from the top-side and turned them clockwise and the current draw went down to 1 amp..

I will reinstall the outputs in the other channel and adjust the bias in that channel as well and see if i have any other problems