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Restoring a Beomaster 1000

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Jeppe
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Jeppe posted on Thu, Nov 17 2016 12:48 AM

This is my first post and I am almost completely new to BO! Having had some Tandberg and diverse Danish vintage equipment, I recently has become very interested in BO as well.

I recently bought two Beomaster 1000's. One with white keys and one with black. Both need restoration. I really want to make these work. I am specially interested in the earlier version with germanium transistors.

I opened the white one up today, and it seems a transistor was burned (marked AC128,3). There was black dust above it on the wood cabinet inside. I wonder if this is possible to replace..? Is there any hope?
There may be other problems as well, I don't know yet. But this seems serious.

Where do you find more rare spare parts for your vintage machines?

How wonderful that there was a little envelope on the inside with schematics inside it!


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chartz
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Answered (Verified) chartz replied on Thu, Nov 17 2016 6:25 PM
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Welcome to Beoworld!

And congratulations on your introduction to B&O's wonderful vintage products.

These Beomasters are nice items.

I for one always find the components I need on eBay. The aforementioned transistors are indeed listed there. Do have a look!

Those AC 128 germanium transistors are (were) quite common and not very difficult to find. There were tons of them used in old radios and tape-recorders.

Good luck!

Jacques

Søren Mexico
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When I start a new project, I go to Martin (Dillen on this forum) first of all, he can provide most of whats needed, then onto E-bay as Chartz

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

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Jeppe
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Jeppe replied on Fri, Jan 13 2017 3:47 PM

Thank you Christian and Martin.

I didn't mean the Beomaster's Loudness should be modified in any way, I don't want them modified. Just meant that the restoration may have brought the built in Loudness back to life, because it seems there was a difference here before and after my "restoration". Sometimes perhaps a restoration becomes a modification by necessity when you can't find original parts, but at least I intend to not modify it.

Perfectly paired with Beovox 1000's.. How sad I missed an auction on tradera.com yesterday of a white Beomaster 1000, a Beogram 1000 and a pair of Beovox 1000. Went for 675 kronor (approx 70 euro).
Felt like now that I have 3 Beomasters (and Christian is kindly helping me with two of them), I couldn't find a reason to buy another one, not at the moment at least..
But the Beovox 1000's, they're good you say..?

At home now a white Beomaster is paired with Castle Kendal speakers, the original version hand built in England in about 1971. Restored by Andrew in the UK, who I again really recommend! It's the third pair I buy from him. https://www.anapeachloudspeakerrestoration.co.uk/
Power handling 40W they say, larger speakers than the Beovox 1000's, but the match is really good!
Below is a photo of them after restoration and while being restored. Not only cosmetically, but internal wiring and capacitors were replaced, and a new pair of drivers to better match the originals (which had been replaced).
I was afraid these would be too big for the Beomaster but it doesn't seem so. Do you have any experience of non-original pairings with Beomasters?

Søren Mexico
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I have run nearly all my speakers (Beovox 1600 to M70) with the BM 1000 no problems what so ever, also some non B&O 4,6 or 8 ohms no problems

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

Jeppe
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Jeppe replied on Fri, Jan 13 2017 5:09 PM

Thank you Sören.

What do you guys think of the built in Loudness? Generally I don't like loudness, so it scared me a bit when I heard that the Beomaster has an "automatic loudness". Mostly, where there is a Loudness button, I prefer it off. On some machines, like my Tandbergs, I think it is too much, overblown. On the Beomaster though, I get the impression it is more subtle.
Does other, more modern Beomasters have this too?

chartz
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chartz replied on Fri, Jan 13 2017 5:34 PM

I don't like that loudness thingy either, but I can live with this one if used with the correct speakers. Not bad at all.

Martin will tell you he's a loudness man, on the other hand. Wink

Jacques

Jeppe
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Jeppe replied on Sat, Jan 14 2017 1:36 PM

It's not bad at all, this loudness thingy!

Do you or someone else know how it works - does the circuit have a fundamental design that makes it work like it had a built in loudness, or is there actually a separate loudness circuit in it?
If the last alternative, do you know where in the schematics it is..? I am very curious about this loudness thing.

Dillen
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Dillen replied on Sat, Jan 14 2017 3:53 PM

It's a filter using a tag on the volume control.
Many people are scared of filtering in general, but that's because they never actually tested their own ears (these people usually
get VERY surprised at the result).
It's a matter of taste - and perhaps habbit - but it's a fact that what your mind will pick up from the music will be quite far from linear if
you are not using Loudness.
Having said that, depending on the choice of speakers, the Loudness in Beomaster 900/1000/1001/1200 etc. could be felt as excessive.

Martin

Jeppe
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Jeppe replied on Sat, Jan 14 2017 4:27 PM

That's what I heard clearly after the "restoration", the workings of this filter. On the unrestored machine this is less obvious.

Bear with me hear, and I hope you don't find me annoying. But I hope this could be of interest also for other fans of the Beomaster 1000 out there who wants to keep their machines in perfect shape. What I was thinking was if there is a possibility that I may have changed the character (or level) of this filter when I replaced capacitors in the amplifier section. I don't know how this filter works, or which parts in the schematics is responsible for it's operation - but say it's one or several 1,6uF 25V capacitors, of which there are several, that I replaced with 2,2uF 25V, then maybe this could be the case..?

Another thing I am curious about, is if the later models 1001 and 1200 also have built in loudness..

Dillen
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Dillen replied on Sat, Jan 14 2017 8:53 PM

Of course a change in capacitor value(s) will change the filter characteristics, but in Beomaster 1000 the
components related to the loudness is fitted physically on the volume potentiometer and none of them are electrolytics so
you won't have changed any of them.

Beomaster 1001 and 1200 also have built-in loudness.

Martin

Jeppe
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Jeppe replied on Wed, Jan 18 2017 5:22 PM

Thanks Martin for advice on loudness and capacitors.

Today I encountered another problem, something very easy (or so I thought), and now I feel like a moron..CryingJust wanted to replace the lamps below the radio scale. Now, I have never had a Beomaster 1000 where these works, but they are supposed to light up when you switch on power, right?
With fresh new lamps that Christian kindly gave me, there is still no light. I measured the connections with my multimeter, and I got the impression that there is no current to the lamps. Isn't this very odd??
The old lamps seems to be ok. Something else is the problem. Fuses seem alright, but that couldn't have been the problem anyway, taken that the Beomaster now works and currently playing Roberto Menescal - Bossa Zen, with a warm, full, lovely sound.

Anyone have an advice for this amateur?

tournedos
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There's a separate fuse for the dial light lamps that doesn't power anything else. The fuse holder is often corroded so your problem might be simply that.

Also, the bulbs are connected in series so either they will both work or both go out at the same time. If the fuse is OK check the lamp sockets. The power to the lamps is AC so switch your multimeter accordingly.

EDIT: sorry, they are actually connected in parallel in BM1000 so likely the power to the lamps is out.

--mika

Jeppe
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Jeppe replied on Wed, Jan 18 2017 7:03 PM

Thanks Mika!
Contact spray on the fuse holder didn't help but I'll do a more thorough cleaning. That must be the problem.

AC, I see, I got some odd readings, wasn't sure which, that explains.

I'll try that and get back with a success or failure report.

Want to say thanks again to all you who have helped me so far! Wink - for your endless patience and your quick replies to my silly little questions. This forum is fantastic. I am amazed with the level of knowledge you have, with even the smallest little details.

Jeppe
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Jeppe replied on Sat, Jan 21 2017 8:44 PM

Thanks Mika for help with the lights!Thumbs Up
It now lights up beautifully. New fuses and cleaned fuse-holders. The lamps didn't light up at first, when I measured if there was any current to the lamp holders with my multimeter they suddenly did light up and continue to do so.

The Beomaster is now playing Cannonball Adderley - Somethin' Else, it seems to have been made for this music, plays it so beautifully.

Christian Christensen
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soD8eJeppe.

 

Its playing now, you can come and pick it up
I have a slight dyslexia. I have trouble of following long threads and long emails.
So I have not read all the posts here.

The problem was driver transistor to the regulator, the one you replaced and most likely the problem is your own cooling invention

The cooling solution you have done is the cause.
The AC128 was shortcut, and did not provide proper level to the power transistor, which made power transistor to level out way to high  voltage. 

 ( based on how it looked like when I got it there is also a speculative reasons that , due to eventual capsel leakage it was short cut with your cooling solution , to the cables in the surrounding )

There is a reason why the orginal colling design is as it is.
The coppar plate rounding must round around the transitor perfect.


The way to to it is to desoilder the entire package of both transistors and the colling plate.

Dillen wrote some where, I cant remember, "lots of strong coffe and good coockies helps"

Now there were more problems. the PCB layout had loosen from one pin,  because of not proper earlier demounting, which of course broke when I repaired, so I had to make sad solutions.
So , the only thing I can teach you is that there are no short cuts, do it right ;) ;) ;)


Beoworld servers didnt allow me to upload images this night, so link is bellow
soD8e

My re-capped M75 are my precious diamonds.

Christian Christensen
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What I did is I took out the entire package, tried my best to restore the rounding of the coppar, to my best and inserted a new AC128 and filled it with silicon paste to hopefully compensate for the not perfect rounding..

Sombody had wrinkled out the coppar rounding so it was crinkled, not easy to get perfect.

Keep the orginal, think orginal. 

My re-capped M75 are my precious diamonds.

Søren Mexico
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Christian Christensen:
Dillen wrote some where, I cant remember, "lots of strong coffe and good coockies helps"

The cookies has to be Danish

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

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