Beocord 9000: Replacing Capacitors

 Now that it is 2017 and the parties are over it is time to get back to the Beocord 9000 restoration. I started the work replacing the electrolytic capacitors. As I mentioned before, on these Beocord 9000 units it is often the case where very little if any recapping is necessary. This unit appears to have been in storage for quite a while and I already found one bad capacitor so I decided to replace the others.

I typically replace capacitors using audio grade capacitors in the signal path and high reliability, 105°C rated, long lasting capacitors everywhere else. In cases where the capacitor is not in the signal path and is 1uF to 4.7uF, I will often replace the electrolyic capacitor with a WIMA polyester capacitor (MKS). For this recap I removed the Beocord circuit boards so I could inspect and clean them better. I want to examine all of the board connectors closely and reflow the solder joints on them.
The first board is the power supply board.

The next board was the rectifier board.

After that as the Analog/Digital Converter board

Followed by the Record/Playback board.

There were three 10uF electrolytic capacitors on the Record/Playback board that I decided to keep. They measured exactly 10uF and had a lower ESR than new replacements that I had in stock.

Since I am also cleaning the Beocord up as I go I removed the Mic. Amplifier board so I could clean the switch and the plugs while I recapped the small board.

On most of these Beocord units I find a green, sticky substance on the shield wire of audio cables at the connectors. This picture is of a cable with that problem connected to the Mic Amplifier board. I cleaned off the goop and re-soldered the shield wire.

Here is the Mic Amplifier board all cleaned up and ready for re-installation.

I should have the remaining Beocord boards recapped tomorrow.