ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Looking better now, shame nobody will ever see it.....
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
I have been following too, of course.
Very exciting thread as always when a BL 5000 is being restored.
👍🏻😀
Jacques
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.
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.
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
You may consider putting spark suppression capacitors to the main switch at this point...?
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?
More work is required on these potentiometers....lot of oxidation towards the rear..
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
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
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
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....
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.
Re assembly under way, its always nice to start putting things back together.....I get nervous with bits all over the place.
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.
Arc suppression components turned up today, they are quite large....will look for the best place to shoe horn them in ;¬)
Snubbers should ideally sit as close as possible to the switch contacts.More here:https://archivedforum2.beoworld.org/forums/t/32196.aspx
Martin
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
Another view....its not close to the transformer or the On/Off switch however.....
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 ??
I'm sure, it'll be fine like that.Definitely better than nothing.
Great....thanks for that Martin, I'll move on more comfortably now ;¬)
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!
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.
This is the part number.....
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...
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 willin 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.
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...
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.
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...…..
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
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
hmmmm...seem to have lost a post, awaiting moderator approval? not had that before
Thanks Martin ;¬)
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.
Cheers Martin.....I will compare with my working Beolab to be sure ;¬)
Loving this thread, thank you for sharing!
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.
I replaced these first so I could put the bottom cover back on...……..