Beomaster 6000 right channel trouble

[iiv]

I recently bought a beautiful 1980’s B&O stereo setup including a Beocord 8004, a Beogram 6002, a pair of Beovox mc120.2 speakers and a Beomaster 6000. So far I’ve managed to fix the record player and it works beautifully – I’ve ordered replacement parts for the Beocord and I plan on replacing the foam surrounds of the speakers. The Beomaster looks beautiful and outputs plenty of power for these speakers, it truly sounds great. However, there is an issue with the right channel and I don’t know quite what it could be.

When I start a record, or tune in a radio channel, or use my phone as a source, the right speaker is sparkly and fuzzy, and sounds terrible. This is fixed either by banging the amplifier – or. and I’m not sure if this really is the fix – by waiting for the amp to heat up. I’m not 100% it’s fixed when it’s hot, but I’ve gotten the feeling that the problem is significantly less likely to pop up then. This is not a speaker or a wire issue, sadly – I’ve tried switching them but it really is the right channel that is the problem. It’s also an on-or-off kind of thing, either the problem is there and very noticable, or it works perfectly and sounds great.

I’d appreciate any help or suggestions or ideas of what might be wrong.

Thanks!

[pepps]

Hello. Sounds like a nice project you have there. Did you also find crackles on the headphones output at the same time as the right speaker output fails?

 

 

[iiv]

I just tested – yes, same problem with the headphones. I also realised that things had gotten worse since I last tried, now hitting/not hitting the amplifier causes all sorts of problems with the display and buttons and playing.

[spassmaker]

Hi

First hitting and bumping these amps seems not a good idea for a repair ;-))

For me it sounds like a cold/broken solder joint.

You said that all sources are involved so there seems to be a problem in the output section of the tonecontrol or the input of the poweramp.

Look for the tonecontrol PCB 3 there are all sources connected and the output to the

poweramp PCB 9.

Look at the output connectors PCB 3  and input connectors PCB 9 for cracked solder joints.

If necessary resolder them, but disconnect from mains before you start, I can tell you: do not solder in a runing amp and don’t ask me why I know this:-))

More BANG than Olufsen

When you change the volume with no source connected is some crackling audible (VOL Pot)

The other problems you discribed seem to have another source on the uPC PCB 2.

There are a lot of connectors which can come loose from hitting and bumping or even cold/ cracked solder joints.

These cold solderjoints are a common problen on these and other B&O gear of this age, but not only related to B&O gear ;-))

Is the poweramp cooling fin getting hot?

The fins should stay handwarm even after 1 hour idling with no signal.

The cooling fin of the power supply PCB 16 are normal gettin hot about 45 to 50 Celsius.

Did you alredy recap the PCB’s (PCB 9) and did you renew the trimmers on the poweramp PCB?

Did you adjust the no load current and the offset of the poweramp?

Only a few hints…let us know if you had progress.

Kind regards

Christian

[iiv]

Thank you! This comment is invaluable, I’ll look into all of these things (I’ve done none of what you suggest so far, haha!). The cooling fins are getting hot though.

[hcraig244]

Love these amps…so over engineered it’s untrue, you should consider replacing all the capacitors as a matter of course, however it’s a good idea to resolve the problem you have first so you know your not introducing additional issues as you go along.
you could start by looking at replacing the four output capacitors first, I have found these caused similar problems to the one your having…..and as you should replace them anyway it’s a good place to start, check out my posts in the archives, I’ve done one or two and they may help you out….enjoy 🤔

[hcraig244]

Just had a thought, is this the 6000 quad amp, unfortunately I have assumed it is 🤔

[iiv]

It’s the “standard” 6000, so not the quad amp. But thanks for your comment either way, I’ll check out your post history 🙂

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