Texas Beomaster 8000: Readjusting the output amplifier assemblies - Part 4

It took a few detours but the Texas Beomaster 8000 finally reached the start of some functional tests.  After the stand alone bench testing of the left channel output amplifier assembly...

I installed the tested output amplifier assembly back into the Beomaster 8000 cabinet.

I rechecked the no-load current and DC offset adjustments of both the left and right channels one more time. 

After verifying those settings were good I got back to playing some actual music through the Tape 1 (TP1) source of the Beomaster.  Both channels sound good.  I will do some real measurements a little later but for now I want to run a twelve hour burn in test of the amplifier assemblies playing music.

I connected a music loaded ipod nano to the Beomaster TP1 source input and started with a volume level of zero. I increased that to a volume level of 4.3 then 5.0 ... playing through my trusty workshop Beovox S55 speakers. 

This is another major milestone.

There are still some restoration tasks though. I hear some typical clicking in the speakers when adjusting the volume. That is due to DC offset in the volume circuit. There are trimmers for the two channels that will have to be adjusted. The FM tuner also does not work correctly.  I will have to determine if that is due to a cable or if there is a component problem on the FM board.

Beomaster 4400 (2419): 30 Hour 60dB Test

Functional testing update...
Because of the earlier incident with the left channel 5R173 and 5R174 resistor failures I am putting this Beomaster through extra long burn-in testing.

Over the weekend this receiver successfully played continuously for thirty hours at a volume level that produced 60dB to 65dB of sound out of my Beovox S55 speakers (measured from 15 feet away).
The output transistors on the heat sinks measured around 100°F to 120°F at various times during the thirty hour test.

The testing continues.