Texas Beomaster 8000: Preamplifier, Filter & Tone Controls

I finished the rework of the preamplifier board along with the filter & tone control board out of the Beomaster 8000 receiver from Texas. The task was pretty much the same as for the Beomaster 8000 from Canada. The electrolytic capacitors were replaced with new capacitors. The LF353N (or TL 072CP) opamps removed and new LF353N opamps inserted. The tone control sliders and source input volume trimmers were flushed out and cleaned with Deoxit. All of the board connector solder joints were reflowed with solder to insure against any weird problems with hairline cracks in solder joints. It is better to be safe than sorry. Especially with audio equipment this heavy.

The two boards look clean and new again. Soon I will be at the point I can give them a try.

Here is the filter & tone control board before the restoration.

Here are the components I am replacing removed.

There were no real surprises on this board except an area on the trace side that had some suspicious looking solder joints around IC102 and IC202. They just didn't look good to me.

I desoldered the bad looking joints and resoldered them.

After the resoldering I discovered one bad area on the board where most of the trace had broken away.  For that one I wrapped a small wire around the pin that connects to the bad trace pad and soldered everything so it is solid again.

That does it for the filter & tone control board.

Now for the preamplifier board.  Here is how the board came.

This is the preamplifier board after removing components and cleaning. I used Deoxit in the source volume trimmers.

This preamplifier board had TL 072CP instead of LF353N opamps. Both are listed as interchangeable devices in the service manual.

The board cleaned up well and I installed 8-pin sockets for the new LF353N opamps.

Here is the completed preamplifier board.