Further examination showed a rusty bottom plate, so I decided to strip everything down to be able to clean and repaint.

The top left pic shows the cleaned plastic part of chassis.

The 2 pics on the top right shows repainted and refitted bottom plate and rear mounting frame.

After that it was time for reassembling the powertransformers and the bottom PCBs, all cleaned and with new caps. Preamplifier module also got new trimmers for setting input sensitivity as the old ones were worn.

The power amplifier PCBs and the display panel had been "over repaired" and got lots of burn marks from hot components.

Some tracks of the power amp PCB were loose or broken, overall in bad shape. The display panel was cracked.

I didnt want to keep it that way so new PCBs were made to replace the old broken ones.

Top left pic shows original power amp board with burn marks

Top right pic shows the 3 new replacement boards (2x module 5, 1x module 8)

Bottom pic shows new and old poweramplifier board

After testing the power amps on the workbench it was finally time to fit them in the chassis. A little tricky and time consuming work.

Most tricky part is to route the cables right so theyre not get damaged in the small amout of place inside the beomaster.

The pic shows the power amplifiers mounted in the chassis.

This is where I am at the moment. More information will come soon as I make more progress with it.

One day it will come alive again

/Fredrik

Very impressive job, you do here !

 🤒 !

Martin

Thanx Martin :D

I just felt the need of saving it from the electronics recycling, hoping that I can get it up and running again...

/Fredrik

How many times I have wished the original PCBs were fibre epoxy instead of pertinax!

That's one determinate repair undertaking 🤒

Wow, great job on those PCB's, Mohawk! Looks really neat!

Must be an exciting project to work on! I dream of having my own BM8000 someday.

I wonder what it's going to sound like with all these modern components in the power amp instead of the old carbon comp/film resistors and ceramic/electrolytic caps. Do you have an 'original' BM8000 for comparison?

I'll be following this great thread!

😂

Speaking of resistors; The ones you have mounted looks like metalfilm resistors.
I think, I would have preferred to stay with carbon types in the amplifier sections.

Another thing is the power rating of the resistors. Several of the original resistors are 1/2 Watt components and
they ran hot (your board is not particularly burned!). Your resistors look like 1/3W or so, which could prove a problem.
I suggest you replace them with 1/2W or maybe even 1W, at least the ones in the "hot" areas.

Martin

Hi Martin,

Why would you prefer carbon types? Closer to original?

Is a higher power rating the reason B&O used the big carbon comp resistors? I always wondered why they were still used even in 1980's equipment as they are said to be rather unreliable and lossy in comparison to carbon film or (said to be even better) metal film.

That said, B&O used components regarded 'not good enough for hi-fi' a lot, like electrolytic caps in crossovers. Yet their products are of great sound and quality so I'm not complaining! 🤒

😂