Kenwood KAC 848

[mike49504]

I powerd this amp up and checked for output.

Out of the B channels i get no sound

Out of the A channels i also get no sound so i checked to see if there was any DC on the outputs..


When i checked the speaker termianls for DC my meter was all over the place from 4 voltd of dc to 1 volt to 3 volts to 4 volts The DC on the output terminals just keeps pulsing all over the place .


Any ideas?

[Perry Babin]

Set all bias pots fully counter-clockwise. Measure the DC voltage across all of the emitter resistors. Do you find any with more than 0.000v DC on them?

[Perry Babin]

A lot of the kenwood amps have problems with broken solder connections on the bias transistors. Check those.

[mike49504]

Set the bias pots full counter clockwise and measured the voltage across the emitter resistors all of them have 0 volts across them..


I reflowed the solder on all of the bias transistors..


Amp still does the same thing

[Perry Babin]

0v isn't the same as 0.000v. Do you read 0.000v on every one of them?

[mike49504]

no 1 of them is pulsing voltages across it

[mike49504]

Ok replaced the emitter resistor that had pulsing voltage across it...


Now i get 0.000 V across everyone of them..


Amps speaker terminals still pulse DC voltage

[Perry Babin]

Was the resistor out of tolerance?

If not, the replacement should have the same voltage across it. Re-check.

If it was not out of tolerance, it may have told you which channel is causing the problem.

[mike49504]

Yes it was out of tolerance

[Perry Babin]

If no emitter resistor has any voltage across it, pull the rectifiers to see if the amp will power up.