Beomaster 8000 Type 1903 - Arizona Restoration Project - Replaced Microcomputer Board Testing

I decided to go with my already restored, early serial number Beomaster 8000 09 Microcomputer module in this Beomaster 8000 receiver.  I re-installed the original unit's metal shielding box on the replacement 09 PCB.

After working with this early serial number Microcomputer PCB, although the shielding box is a pain to work with, I should have removed it by focusing my de-soldering work on just the tabs that were soldering onto the shield box lids.

Reinstalling the box is much easier than removing it.

Here is a picture of the new Microcomputer PCB at the corner where the original board had broken traces.
Everything is good with this 09 module.

Here is the new Microcomputer board reinstalled in the Beomaster 8000 cabinet.

I went through all of the control panel functions both with the control panel buttons and the remote control buttons.

Everything worked as it should except that the FM station display has the two missing LEDs.

I can deal with the display LEDs later.

Right now I wanted to try out this Beomaster 8000 and see how it sounds.

Before doing that though, I needed to check the No-Load Current and DC Offset of the Beomaster 8000 Output Amplifier boards per the service manual.

Both the No-Load Current and DC Offset values needed adjusting.  

Here is the No-Load Current check after I adjusted the TR226 trimmer on both channels.

Note: These checks and adjustments are made with no speakers connected and the volume at zero.

No-Load Current

DC Offset

Those service manual adjustments encountered no problems so I moved on to some real listening tests.

I connected up an FM antenna and an iPod Nano to Tape 1.
I connected a pair of Beovox MC 120.2 speakers to Speaker 1 outputs of the Beomaster.

I will leave the Beomaster 8000 playing for several hours with the volume level at a low volume level (2.4).

Beomaster 1900 Type 2904: New idle current trimmers and output transistor thermal insulators

I started to work on replacing the electrolytic capacitors on the last board, the tone control and FM tuning control board. Unfortunately I ran out of my favorite 2.2uF WIMA capacitors. There is a Mouser distribution center close to me however so the parts will arrive tomorrow.

In the meantime I will go ahead and change out the left and right channel 250Ω trimmer resistors that are used to adjust the output amplifier no-load current. Now is a good time to change them.

Here are pictures of the trimmer replacements.

Along with that change I cleaned off the old, dry thermal insulation paste on the four output transistors that are mounted on heatsinks in the back of the Beomaster. I like replacing that with new Sil-Pad thermal insulators.

Here are the heatsinks reinstalled.