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Beomaster 4000

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Peter
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Peter posted on Sun, Apr 3 2016 12:30 AM

This nice Beomaster has its first 4 switches to the left that do not stay latched. I believe it suffered some beotrauma forcing them inward since they are shorter than the rest of the switches by 4mm. Before I tear it's face off to investigate, are there any surprises I should look out for taking the face apart? I've never dismantled a Beomaster of this era and would like to get it back together.

Peter-

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Peter
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Peter replied on Sun, Apr 3 2016 12:36 AM

Kind of see the descending shortening of the switches

Peter-

Peter
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Peter replied on Sun, Apr 3 2016 12:39 AM

Couple caps were replaced with good quality high temp caps at some point. It seems as if some trimpots were replaced too. Runs nice and cool. Sounds great. Should I switch out the orange capacitors too?

Peter-

chartz
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The orange ones (and the grey ones too for that matter) seem to be less prone to failure than the dreaded red ROE ones. I'd replace anyway, for peace of mind.

Jacques

Peter
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Peter replied on Sun, Apr 3 2016 2:39 AM
Thanks for your response Jacques! In replacing the 5000uf grey filter capacitors, could I use 4700uf? It seems like they are much more common.

Peter-

chartz
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chartz replied on Sun, Apr 3 2016 10:11 AM
Peter:
Thanks for your response Jacques! In replacing the 5000 µf grey filter capacitors, could I use 4700uf? It seems like they are much more common.

Of course, no problem at all. Choose the ones that fit, even if the voltage is higher. Alternatively, you may use some plastic foil to adapt them. These caps are usually still fine though.

I'd also replace the trimmers whatever they look like.

As for the keys, they indeed seem to have been pushed-in at some point. I would incriminate mishandling.

The fascia is easy enough to remove. Just be careful with the tuning meter. It is less so to put it back in place - the phone socket, bulbs, and tuning indicator all need special care. You'll see what I mean when you have the thing aside!

The switch bank stays in place, fortunately.

Jacques

Peter
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Peter replied on Mon, Apr 4 2016 12:48 AM

Thank you again Jacques for your help! That helped nicely. Here is what I found:

The bank of switches was indeed bent. Pliers and muscle, not often the most useful tools with B&O but today that's all that was needed. All the switches work as they should. Lamps all light up (for now), now just waiting for the trim pots and capacitors to arrive.

I just finished recapping and wiring a set of Beovox 5700's and this will make a beautiful friend to them. Super excited.

Peter-

Søren Mexico
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Good job Peter, we are following

Collecting Vintage B&O is not a hobby, its a lifestyle.

Peter
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Peter replied on Mon, Apr 4 2016 1:47 AM
Ah thanks Søren, I've referenced your CD50 servo motor repair instructions so many times. So very appreciative.

Peter-

chartz
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Well done Peter! We need more pictures!

When the trimpots are replaced, please adjust as per service manual. Have you downloaded the service manual yet?

Jacques

Peter
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Peter replied on Wed, Apr 6 2016 2:11 AM

Thanks! Indeed I have downloaded the service manual and I have schematic from the secret envelope. Reading ahead as I wait for my parts to arrive, I don't think I understand how to adjust these idle trimmers. My only experience has been with the BM 5000 where it was very clearly described. Where do I attach my leads? Here are the instructions:

This is what I see:

the black trim pots are the 250 ohm currently installed. This is a later model with the added 4 extra trimmers flanking the black ones that the service manual says to not touch, with repercussions being...an unknown silent future?
So anyway, what does the "r/hv" stand for that is mentioned in the service manual diagram? I can't find it referenced in any of my intro to audio component repair books. Still learning every day.

Peter-

Craig
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Craig replied on Mon, Apr 11 2016 8:11 AM

Peter

Good morning......I will be following your posts closely as I too am about to embark on this same adventure, having acquired a Beomaster 4000 (2406) on ebay for a very reasonable price I thought it was the least I could do to try and bring it back to its previous best. Everything seems to work, front facia is a bit faded by direct sunlight, and on initial power up I get a series of "snap/crackle and pop, this occurs on operation of most of the switches and sliders during operation too, opening the case reveals lots of dust and dirt so the first task will be a blow down with an air duster followed by servisol 10 contact cleaner, if I can get at the switch contacts which are buried within the bowels of the machine! I have received a kit of parts from Dillen which includes a lot more pots than I was expecting, the service manual isn't too clear on the reset values for all these little devils and to complicate the task further I don't have signal generator or scope, so some of the pots may have to stay original......however I will post pics of this adventure and hopefully we can swap horror stories as we both progress

Peter
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Peter replied on Mon, Apr 11 2016 1:38 PM

Hopefully our stories will be of continued success and not horror! I ordered replacement pots for all but I only plan on replacing the 2 bias current pots since I also lack the proper equipment for setting the others. I am on vacation In Texas right now and look forward to returning home to a mailbox full of components. Until then I'll be looking forward to some pictures!

Peter-

Steve at Sounds Heavenly
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The cable workshop, Leics, UK
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Hi Peter,

I've just checked in my loft and I still have my old UK-spec Beomaster 4000 from many years ago (slight damage to case, electrical condition unknown, but all switches working).  Please let me know if you are interested in a "donor amp" at a very reasonable cost and I can get the switches and other parts checked out!

Kind regards, Steve.

Steve.

www.soundsheavenly.com

Sounds Heavenly are proud to sponsor the BeoWorld forums!

Peter
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Peter replied on Tue, Apr 12 2016 1:01 PM
Thanks Steve! I'm imagining shipping this heavy baby to the US will be exorbitantly expensive. Maybe if the cabinet isn't too damaged this could be a good candidate for a restoration?

Peter-

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