A Pair of Beomaster 1900 Receivers for Restoration: Capacitor Replacement on Unit #2

 The first unit of the two Beomaster 1900 receivers I am restoring was completed and has been in a listening room going through its operational testing. While I am enjoying that part of the restoration there is still the task of restoring the second Beomaster 1900 unit.

I did the initial assessment of this second Beomaster 1900 a while ago. Here is a link to that post.

I will start this post out with the Beomaster 1900 opened up and ready to start in on the capacitor replacement on the main circuit board.

The main circuit board is where the majority of the capacitors being replaced are located.
Unfortunately the board does not unplug so it can be removed for working on.  It must remain wired to the wire harness on the end where the transformer is located. 

Changing the capacitors on the main board usually means flipping the Beomaster unit over and back a bunch of times during the de-soldering of old capacitors and soldering of the new capacitors.
If you have a good memory you can de-solder and remove a bunch at one time.  For DIY restorers that may only ever do one of these receivers it is safest to just do one capacitor at a time and take care to make sure the polarity and the value is correct.

Because there will be a lot of movement with this large, main board I always de-solder the two transformer secondary power wires to the board before beginning the recapping task. This avoids having those wires bent back and forth.

To loosen the main board so it can be flipped around and worked on there are several screws that mount the board to the cabinet chassis. There are also screws top and bottom for the four heatsink assemblies used by the four output amplifier power transistors. My restoration plans are to change the thermal material on those transistors anyway so I removed the heatsinks and clean off the old thermal paste.

Now the main circuit board can be put in what I call its service position. 

I use a crude, makeshift jig from some foam blocks but it works good and protects stressing the main board while I am working on it.

Here is the main board with all of its old capacitors.

Here is the replacement of the filter capacitor for the Beomaster 1900 +15 VDC power supply.  I also changed the thermal paste on the chassis mounted transistor to a small Sil-Pad.

On the two large filter capacitors for the Beomaster 1900 ±31 VDC power supply rails, I reorganize and attach terminals plus heat shrink material.

That is a good, solid connection that won't come loose

The rest of the capacitor replacement on the main board is lengthy and tedious but uneventful.

Here is the completed board.

Now only the Volume PCB and the Tone, Filter and Tuning PCB remain to be recapped.