Denon AVR-1910 power amp repair

[Rutherberg]

Hi,

I have a Denon AVR-1910 here with a pair of power transistors shorted on the front right channel (Q1201 & Q1202), resulting in blinking red led when powering up the unit.

Is there other components to check/replace by default when power transistors are shorted ? I attached the power amp schematic.

Thanks in advance

[willb]

I've repaired a lot of these Denon receivers with failed outputs. You definitely want to check R1231FR, R1232FR, R1238FR, R1239FR, R1236FR, R1237FR, and D1201/1202- Z1201/1202. The emitter resistors always go open on these, and I usually find at least one of the SMD zener diodes to be shorted. 

[mzacharias]

I could fix these and similar models all day long. Did warranty work for Denon for over 20 years. Retired now but I still keep a stock of those output transistors, some original zeners, etc and a few scrap boards around for the odd small parts. I miss doing these on a regular basis. I do occasional work for a couple shops in town but rarely any blown channels anymore. 

[rfengg]

Glad you could trace it to the output transistors.
As far as I know, the protect kicks in when the Safe Operating Region of the transistors is exceeded, thermal excess  or when there is average DC on the speaker outputs.
I fought a losing battle with my AVR 1512 which used to kick into protect randomly.

So what did I do? 
Disabled the ASO_DET line which was the offending signal causing it to go into protect and have been using the amp fine for 2 years now......of course, with a fire extinguisher next to the 1512, just in case.............

[apellegr06]

Hi,

@Rutherberg Have you finally found the problem ?
Because I have a similar one.

Regards
Alain