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Craig
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Looking better now, shame nobody will ever see it.....


Craig
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Removed the front panel and as with the other units I have disassembled I found a piece of foam rubber that immediately turned to dust when disturbed....what is the purpose of this foam, does it need to be replaced...….I haven't bothered in the past because I couldn't see the need for it......anybody??

Craig


chartz
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chartz replied on Mon, Dec 23 2019 8:06 AM

I have been following too, of course. 

Very exciting thread as always when a BL 5000  is being restored.

👍🏻😀

Jacques

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Craig:

Removed the front panel and as with the other units I have disassembled I found a piece of foam rubber that immediately turned to dust when disturbed....what is the purpose of this foam, does it need to be replaced...….I haven't bothered in the past because I couldn't see the need for it......anybody??

Craig

If I remember correctly it is sitting between the big 5 W resistor and the power on lamp, probably for heat retention

 

 


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

chartz
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chartz replied on Mon, Dec 23 2019 3:10 PM

How much would a BL5000 cost to manufacture today? Let alone its retail price. Incredibly well-made, and pity so many were put aside in damp environments.

Mine was not presenting any rust because it spent its life in a living room, probably in a cabinet (no dust) so I didn't have to do anything. I was lucky.

Still in use and working perfectly!

I was wondering whether it is possible to restore the transformer to its former tinned condition (and other B&O transformers for that matter). I don't like the idea of painting it at all!

Great work Craig, as usual.

Jacques

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chartz:
I was wondering whether it is possible to restore the transformer to its former tinned condition (and other B&O transformers for that matter). I don't like the idea of painting it at all!

I think the transformer housing is electro galvanized with zinc and not tinned, it would be nearly impossible to do that with the transformer in the housing, what is possible is giving it a layer of nickel electro plating it, I think Craig did electro plating on some switches with copper, it is the same system but in a bigger scale I use it in my job repairing printing cylinders in offset machines here applying the last layer of cobalt on a damaged section filled with copper

 


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

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Beo_Jean replied on Tue, Dec 24 2019 3:06 AM

You may consider putting spark suppression capacitors to the main switch at this point...?

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Craig replied on Tue, Dec 24 2019 7:39 AM

Beo_Jean:

You may consider putting spark suppression capacitors to the main switch at this point...?

Good idea Jean......do you know what would be the best size for such a cap?

Craig

Craig
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More work is required on these potentiometers....lot of oxidation towards the rear..


Craig
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And the bracket holding the rest of the selectors is also in need of some attention.....however the festive period is upon us and I will need to focus on matters of eating and drinking far too much.....back burner for the Beolab.

Have a happy holiday everyone Beer Big Smile

 


Beo_Jean
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Craig,

This is the network I'm using to minimize switch arcing.

The one across the AC lines located before the transformer, called an RC snubber, is the Cornell Dublier 104M06QC100.  This snubber is an assembly of an 100 ohms resistor and 0.1uF film capacitor made for that purpose.

Additionally, it was recommended to me by an expert, to add ceramic capacitors across the switch contacts of 10000pF 1Kv.  I never added those before but will certainly try them on my next restoration.

Looking forward for the end result!

Charles 


Craig
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Charles

Thanks for that advice, I have the parts on order and will fit them in due course. As for Jacques commen t "How much would a BL5000 cost to manufacture today? Let alone its retail price. Incredibly well-made"  take a look at these linear potentiometers, if you could find anyone to fabricated something like this today it would be very expensive



Craig
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I don't think anyone manufactures this sort of thing with a view to repair/overhaul these days, and once done the action is so smooth...graphite grease on the tracks and silicone grease on the guide rods....


Craig
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Finished items......the tiny carbon cones comprising the contacts all looked in good order, though a couple fell out and I counted myself fortunate to be able to find them once they dropped to the table top.

 


Craig
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Re assembly under way, its always nice to start putting things back together.....I get nervous with bits all over the place.


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As I now have lots of space where the huge capacitors once sat I have re routed the power cables to this side of the transformer, this makes it less congested over by the voltage selector and fuse side.


Craig
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Arc suppression components turned up today, they are quite large....will look for the best place to shoe horn them in ;¬)


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Dillen replied on Mon, Dec 30 2019 12:47 PM

Snubbers should ideally sit as close as possible to the switch contacts.

More here:
https://forum.beoworld.org/forums/t/32196.aspx

Martin

Craig
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Hmmmm…...this is what I've done before reading the thread above, I have essentially connected the Dubilier across the coils of the transformer downstream of the On/Off switch in a tucked away place 

 


Craig
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Another view....its not close to the transformer or the On/Off switch however.....

 


Craig
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The 0.01uf caps are connected directly across the switch contacts...….I'm reluctant to solder any more connections to the switch as its a little busy there already.....any advice ??


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Dillen replied on Mon, Dec 30 2019 1:40 PM

I'm sure, it'll be fine like that.
Definitely better than nothing.

Martin

Craig
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Craig replied on Mon, Dec 30 2019 1:45 PM

Great....thanks for that Martin, I'll move on more comfortably now ;¬)

Beo_Jean
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Craig,

Your ceramic capacitors are much much bigger than the ones I bought.  Sorry, I should have gave you the part number in first place... (See picture)  Wondering now which is the wrong capacitor...? what's the part number you bought?

BTW, very nicely done so far!


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Dillen replied on Mon, Dec 30 2019 2:10 PM

It MUST be a Class X or X2 type!
They're the only ones approved for use directly across mains, as they are "self-healing" rather than exploding.
They are usually metallised film types and clearly marked.

Craigs are correct.

Martin

Craig
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This is the part number.....

 


Beo_Jean
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Beo_Jean replied on Mon, Dec 30 2019 4:19 PM

Dillen:

It MUST be a Class X or X2 type!
They're the only ones approved for use directly across mains, as they are "self-healing" rather than exploding.
They are usually metallised film types and clearly marked.

Craigs are correct.

Martin

Martin,

In this particular application (dual contact switch), the ceramic disk capacitor is NOT used across the mains (Neutral, Line) but across the switch poles where you have one contact per line.  That said, The Dublier RC snubber MUST be, as you said,  an X rated capacitor because it's located across the mains after the switch but the ones across the switch contacts are on the same line.  So which factor they require, if any?  I need to investigate...

But this thread is not about X factor or not capacitors, I'll just let it go...

 

 

 

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Dillen replied on Mon, Dec 30 2019 6:13 PM

In the case of a faulty switch - if one contact never closes, there will be no current flow through the transformer and the cap across the open contact will
in fact be sitting across mains.
Same thing will be the case for the short period of time of powering up and down, when one contact is closed and the other one open.
Always use Class X or X2 for mains related jobs.

Martin

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Beo_Jean replied on Mon, Dec 30 2019 6:36 PM

In this respect I must agree then.  I always used only an RC snubber (Like the Dublier) across the mains before and never added those supplement caps across the contacts.  Thanks for the clarifications.

Sorry for the distraction; DJ the show must go on please... 

Craig
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Craig replied on Tue, Dec 31 2019 9:10 AM

Thanks guys.....you have filled a hole in my knowledge of arc suppression over mains switches, I will make it a "too do" on all projects moving forward.

Craig

Craig
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All major components back in place and following a gentle power up with the variac was pleased to see no massive current pull and no smoking wires or components...…..


Craig
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As I was all hooked up a test run was required, its good to know everything is working correctly prior to starting to replace all the components and pots.....so the BG4000 was employed


Craig
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Craig replied on Fri, Jan 3 2020 11:27 AM

And everything worked fine...…...however, there is always an "however". When adjusting the volume slider the volume went very high after only a small amount of travel from zero.....moving the slider higher increased the volume until I was about 20% travel then the volume dropped to a more acceptable level.....it then increases steadily as the slider is advanced up. I'm suspecting I may have been a little clumsy with the graphite grease here so may need to remove the volume slider and take a look inside....for the minute, unless anyone has any suggestions I will carry on with the recap and pot change out then give it a go after that is complete

Craig
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Craig replied on Fri, Jan 3 2020 11:31 AM

hmmmm...seem to have lost a post, awaiting moderator approval? not had that before

 

Craig
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Craig replied on Fri, Jan 3 2020 11:33 AM

Thanks Martin ;¬)

 

Dillen
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Dillen replied on Fri, Jan 3 2020 11:35 AM

Craig:

hmmmm...seem to have lost a post, awaiting moderator approval? not had that before

Can't tell you why either, but it has been sorted now.

Check the wiring to the volume potentiometer, check the leads haven't been mixed up. Particularly the ones for the Loudness tags.

Martin

Craig
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Craig replied on Fri, Jan 3 2020 11:38 AM

Cheers Martin.....I will compare with my working Beolab to be sure ;¬)

Craig

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StUrrock replied on Fri, Jan 3 2020 12:24 PM

Loving this thread, thank you for sharing!

Craig
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Gave the volume potentiometer a good hard looking at and sadly all the wiring was in the right place, was a little disappointed at this as I now had to dismantle the front panel all over again to look inside the offending item. Spent all afternoon doing this and replacing the 6 off capacitors that sit in the bottom of the PW Board.


Craig
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I replaced these first so I could put the bottom cover back on...……..


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