Moving BM8000 internals

Hi Guys,

I've recently gotten hold of another BM8000 that's in excellent cosmetic shape and looks like it's never been worked on. It doesn't work properly and I'm sure is in dire need of a recap and new trimmers.

My BM8000 which I got last year has been excellently fixed (it arrived damaged) and restored (to the extent I could afford) by Olly and I'm happy with it. I recently recapped the PSU board (the only old caps in it now are the 2 on the CPU board and the filter caps) with a kit from Martin and it's more or less perfect, apart from the CPU board had a crack in it (fixed by jumper wires) and it's got the European 220v PSU in it.

I was thinking of moving the CPU board (it looks the same) and the 240V PSU over to mine.

Any advice or tips?

Thanks. Lee

Oh forgot to mention... My restored BM8000 has the monitor function on TP2 and the 240v one has it on TP1. Is this a software difference on the CPU board as well as a different input panel and preamp board?

I haven't messed with the monitor circuit on any of my Beomaster 8000 units but the actual switch routing of the audio signal to the output amplifier would have to occur on the preamplifier board. The selection of the selected source does come from the processor board. So I don't think swapping processor boards would change your monitoring function.

According to the preamplifier part of the schematic shown here, if FM, Tape 2 or Phono are selected as the source to listen to, IC202 (AD 10/278) selects the appropriate signal. That signal routes up through IC4 (AD 10/192) where it continues on to the output amplifier. The selected source signal also routes to the TP1 record inputs via IC7 (opamp). If the user wants to monitor TP1, the IC4 (AD 10/192) switch can switch the TP1 outputs to the BM8000 output amplifier without disturbing selected master source signal to the TP1 record inputs.

Going the other way, if TP1 is being used as the master source, its output signal is routed through IC4 (AD 10/192) to the output amplifier. That signal also routes over to the TP2 record inputs so TP1 can record to TP2. At this point you wouldn't want the monitor switch to switch TP1 out because that would interrupt recording to TP2. The control signals for the preamplifier signal switching (IC4 and IC202) come from the processor board IC4 (6500/1) Slave. o, q, p and r in the schematic.

I wasn't aware that the monitor function changed on some of the BM8000 units though. I would like to see a picture of the schematic of the other one.

sonavor