Solid state bias adjustment.


I've recently replaced the output transistors and caps on a Denon poa-2400 that had a blown channel.
It works and sounds fine. It does not run hot no matter what I throw at it.
How critical to sound and component longivity is the bias adjustment?
According to the service manual I would need to purchase a function generator at minumum to set it.
All my other equipment is Denon and I see broken units for sale all the time.
Thanks for any help or information.
danno25
Danno25, The bias adjustment is important. If improperly set you will get either excessive heat or excessive crossover distortion, especially at low power.

Many SS amps have a bias and a DC Offset control. I would start with the DC Offset- the amp should read 0.00V at the speaker terminals. Its likely that you will not be able to actually hit that reading due to noise. But you should be able to get it so that it drifts back and forth across 0Volts.

If you don't have an audio oscillator, you can use the DC Voltmeter to read the voltage drops across the emitter resistors of the good channel. Although they too may have drifted over time, if that channel has been behaving OK (heat and sound is nominal), the bias may be set fairly close to correct. You could then duplicate those readings in the repaired channel.

Be careful with the meter probes! You don't want to have to replace parts again... -good luck!
Thank you very much.
I've got the dc offset going from -.01 to +.01 and it's as close as I can get it to .00.
As far as I can tell it all matches the other side.
I think it's time for me to invest in some more diagnostic equipment.