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This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022

 

BM1000 modification

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This post has 6 Replies | 2 Followers

Christian Christensen
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Stockholm
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Christian Christensen Posted: Sat, Nov 1 2014 2:16 PM

Sometimes when I read service manuals I find interesting charming notes like this, the designer opening creative doors for modifications

It makes me smile, for moment fantazising how interesting it would be to meet the designers of these products., who they are, which ideas and thoughtprocesses  they had at the time.

Wondering if anyone ever did this mod to a BM1000 because the users need for a microphone amp in their living room was bigger then having built in RIAA amp.

Charming thoughts , that makes me take small fantazising breaks in my beoing 

.

My re-capped M75 are my precious diamonds.

chartz
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Burgundy, France
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chartz replied on Sat, Nov 1 2014 6:04 PM

Interesting!

We could open a very lengthy thread about that.

There are many mods like this in the various SM, plus I guess a countless number of separate service sheets that were sent to workshops.

I have yet to open my own Beomaster 1000, given to me by Dave Farr when I visited him two days ago! I will start a new thread about the restoration process, there isn't much on Beoworld about it.

Jacques

Christian Christensen
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Stockholm
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Yes, anyone alse here seen interesting mod suggestions in the service manuals ?


I am just to finish the refurb of a BM1000 that is to be sold to a friend together with a pair of S45, and a dual turntable.

In the BM1000 I have replced the power supply caps and the output caps.

Ontop of that I replaced a bunch of Röde caps in the power amp. Reason for that is to secure the functionality of the poweramp

And I have also replaced the 2,2 uF tantalium caps that is the output of the preamp.
If those tantaliums would shortcut over the years the  preamp would feed DC to the poweramp.

Actually when jus about finished, I found a slight hum in the left channel, it was enough to drive me crazy. My oscilocope could not pick it up.
Could error track that it was the last stage of the preamp.
All caps ESR measured okey..so I hgad to guess, and by guess it was the powersupply capacitors on the preamp on 100uF  639 and 646 that was the cause ..and it was.them. hum disapeared.


My re-capped M75 are my precious diamonds.

Christian Christensen
Top 150 Contributor
Stockholm
Posts 512
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Ahh..not...still have the hum in the left channel...:(

My re-capped M75 are my precious diamonds.

Christian Christensen
Top 150 Contributor
Stockholm
Posts 512
OFFLINE
Bronze Member

Found the problem, left channel didnt have correct voltage level,
Unvisable aborting on the PCB layout, fixed with additional cabel.

Tomorrow, my female friend will have B&O culture in her home :) :) :) 

My re-capped M75 are my precious diamonds.

Christian Christensen
Top 150 Contributor
Stockholm
Posts 512
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But I agree, taking it back to thread..I have also seen these comments on several  schematics.

Could we collect them ?

Pickup these threads and lets talk about them 

It is  traces to designers thoughts, in an very odd way that you never see in american and japanese service manuals

 

Who were the people that designed this unique machines....interesting ? 

My re-capped M75 are my precious diamonds.

tamtapir
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Örebro, Sweden
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This is certainly a worthy topic for a BeoWorld thread! I look forward to reading it and will try to contribute after ability.

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