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
I have an old Beomaster 3000-2 (2402) which I have been trying to get back up and running. Signal path is now nice and clean, but the mains transformer is vibrating/humming.
I have tried to decouple the capacitor from the chassis with rubber grommets but this hasn't improved the hum much.
Looking at the schematics, the mains transformer has a 22V tap and a 43V tap.
Would there be any problems with replacing the original transformer with a pair of toroidals for each output voltage? Obviously an original transformer would be like hen's teeth.
I'm not worried about having the mains voltage selector as I have no plans to deviate from UK mains.
I'd replace the transformer only, so rectifiers and everything upstream of those would be untouched.
Thanks in advance!
James
In my opinion it'll be shame, despite it may be necessary to keep the unit running - wouldn't be better solution to get original transformer from same unit and keep it crispy original?
Some parts may prove difficult to be find, but there seem to be quiet a few non working or working units on eBay decently priced (your solution won't be for free neither ) but that's my personal view - I like to use original parts only while restoring unit.
Bob
Once you start altering it, at which point should you stop call it B&O
jamesymurray: I have an old Beomaster 3000-2 (2402) which I have been trying to get back up and running. Signal path is now nice and clean, but the mains transformer is vibrating/humming. I have tried to decouple the capacitor from the chassis with rubber grommets but this hasn't improved the hum much. Looking at the schematics, the mains transformer has a 22V tap and a 43V tap. Would there be any problems with replacing the original transformer with a pair of toroidals for each output voltage? Obviously an original transformer would be like hen's teeth. I'm not worried about having the mains voltage selector as I have no plans to deviate from UK mains. I'd replace the transformer only, so rectifiers and everything upstream of those would be untouched. Thanks in advance! James
Don't worry - be Happy
I do understand what you mean, and ideally I would like to replace with another original transformer, but they seem very hard to come by, even units for spares/repair, in the UK.
Hypothetically speaking, if one was to go down the route of a pair of toroidals to provide the 22v and 43v rails what VA would be required?
22v toroidals are common to come by, but 43v not so. Would 44v/42v prove too much/too little?
I think the transformer for the BM 2400 is the same, after rectifiers it has 15/31V.
As the in coming line never is stable at exact 220 or 240, 42/44 V should not give problems.
But I have the same opinion as Bob, get a used unit and use it for spares, you may even be able to sell some of the rest.
Collecting Vintage B&O is not a hobby, its a lifestyle.
There is quiet a few on eBay usually (only now seem be just 2 good ones listed)
my grandma used to say: patience brings the roses
bob
p.s. not long ago there was few under £20 - I've bought one for parts under £30, which I've restored and sadly have to sell
jamesymurray: I do understand what you mean, and ideally I would like to replace with another original transformer, but they seem very hard to come by, even units for spares/repair, in the UK. Hypothetically speaking, if one was to go down the route of a pair of toroidals to provide the 22v and 43v rails what VA would be required? 22v toroidals are common to come by, but 43v not so. Would 44v/42v prove too much/too little?
It got me thinking..... so I've checked service manuals (as I remember working on mine and comparing to BC3500) to see if those two have same transformer - it appears that they do BC3500 Part Nr 8013057 and BM3000-2 Part Nr 8013058 ;)
Make long story short - I have one for you
pm if interested
P.S. I'm braking the unit into parts and selling all for charity see post: http://archivedforum2.beoworld.org/forums/p/2611/27650.aspx#27650 very bottom :)
jamesymurray: I have an old Beomaster 3000-2 (2402) which I have been trying to get back up and running. Signal path is now nice and clean, but the mains transformer is vibrating/humming. I have tried to decouple the capacitor from the chassis with rubber grommets but this hasn't improved the hum much. Looking at the schematics, the mains transformer has a 22V tap and a 43V tap. Thanks in advance! James
Problem is this is a rather common problem with these units so buying an old replacement is no guarantee of this happening again. If you can find a good fitted modern replacement solution then IMO that will be the best option!
Olly
I happen to respectfully disagree
Parts I'm offering are coming from fully working unit, question remains if the hamming is caused by the main transformer in first place - modern solution is NO NO for a vintage product in my opinion
b
Step1: Problem is this is a rather common problem with these units so buying an old replacement is no guarantee of this happening again. If you can find a good fitted modern replacement solution then IMO that will be the best option!
Being very non technical, I don't wish to weigh into this discussion particularly! However I do believe the 3000 type transformers have a tendency for the core to delaminate and this can be a source of hum. Certainly both mine hummed and the 4400 I had did as well. The 4401 seems immune just at the minute! I think you can rebuild these though it is clearly labour intensive!
Peter
If 3000's were rare, or a new transformer somehow effected the performance I would wholeheartedly agree with you Bob, but they are pretty common, and as long as an original transformer could later be put back in there then I don't see a problem!As Peter has said these transformers are prone to failing, and I am sure they are potted so I don't know where this leaves a rewind?I believe Martin was looking at having custom made unit built but not sure how far he got with this?
Hmm, funny though - I've had 2 BM3000-2's (original virgins) and none of them seem have the problem, I also have 2x BC3500 (with same type of transformer and the oldest is 1972) yet again no problem with so called common issue with hamming due deterioration of core of main transformer, never the less.
Some are saying they're common (not rare) units - why in the heaven would you like to put anything what doesn't belong there in, than? To me it will only make sense if the replacement parts won't be available at all, but the question of integrity and originality will remain NO Matter what.
There was another posts when people been going crazy because of few tiny holes in speakers, caused by handles been fitted to them, some went mad about "at what point you stop call it B&O" - yet many are more than comfortable to replace just about anything on their units, bit of double standards
is it?
Bob:Some are saying they're common (not rare) units - why in the heaven would you like to put anything what doesn't belong there in, than?
So...whenever you replace electronics in there you use original stock from the 80s? Where do you even get Roederstein-branded capacitors these days?
If it fixes the problem, why not replace old parts with better new parts? I always favour that approach before "get another unit to fix yours" - because that still leaves you with one working and not working unit...which is exactly where you started.
I've had quite a few of these humming transformers. Annoying to say the least. I'd put the chance of finding a "quiet" original one at 50/50.
Yeah I do,
(70's in this case ;)
and probably the reason why not is, that I don't want to build B&O replica's, regardless on fact if it fix the problem or not, (in that case possibilities be endless, just keep the "badge")
beside there is lots of units very reasonably affordable to buy - hence question remains - is it worth fixing with substitute in first place?
I don't mind to have another unit for spares as there's always whole bunch of people needing spares and parts, but that's just me ...
I've already "answered" your remark: If original parts cannot be obtained and the unit is worth repairing - there is no other option than replacement substitute or just get another working unit
ablaumeise: So...whenever you replace electronics in there you use original stock from the 80s? Where do you even get Roederstein-branded capacitors these days? If it fixes the problem, why not replace old parts with better new parts? I always favour that approach before "get another unit to fix yours" - because that still leaves you with one working and not working unit...which is exactly where you started. I've had quite a few of these humming transformers. Annoying to say the least. I'd put the chance of finding a "quiet" original one at 50/50.
Bob: I don't mind to have another unit for spares as there's always whole bunch of people needing spares and parts, but that's just me ... I've already "answered" your remark: If original parts cannot be obtained and the unit is worth repairing - there is no other option than replacement substitute or just get another working unit
Now Bob tell me the difference between changing a transformer with a newer better one, and changing 30 ROE caps with new ones, the innards are no more original, but if you dont do the change you will have a not working unit, what I do is to keep the unit as close to original as possible and I would never do anything to change the performance or the design of the unit, but if I have a unit not working, I will do everything I can to get it working and looking like the original, I have used hours to keep my units working and looking that way. The way you are doing it, you will end up with 1 not working unit for each working unit you have, for me thats not the way to go, we have save all unit possible and as close to original as possible, but just scratch a unit to get get another one going is not the way to go.
Sorry Bob, but I have to agree with Ablaumaise on this one, I just wish he had a name easier to spell
This is a perfectly reasonable divergence of opinion - one that is seen is many different areas - classic cars are another example. Some will want absolute originality so that the device is just as intended: others will look to make the device better or more practical. Neither is wrong, but are looking at the issue from different standpoints. The ones I don't really get are those who use uprated parts and then clothe them in the coverings of the originals!
Peter: The ones I don't really get are those who use uprated parts and then clothe them in the coverings of the originals!
The ones I don't really get are those who use uprated parts and then clothe them in the coverings of the originals!
Yes, we can drill exterior of ROE's away and glue it over new elko
blah-blah and photographs as needed
Ola Søren,
Think is I can't tell you the difference - it's personal view, I've already said that one must make the decision for himself if the unit is worth "updating" in the first place or, shall became "spare donor" otherwise there be no line what's original and looking like one.... I'm sure you'd know know the right answer, shall you be at the receiving end (purchasing one of those)
And no I don't have all units double, I don't collect anything coming my way, but make choices (don't need to own the whole production line) and keep what I like and want, not to mention can use, perhaps I was lucky that none of my unit suffered such a common fault, but personally I've reservations (no disrespect anyone) for one single reason: (even in my relatively short life on here) I don't recall more than 1 thread concerning hamming of Main transformer on BM3000-2 - you do the maths. to me 4 units without any problems in that area is rather statistically good enough not to take notice
Søren Mexico: Now Bob tell me the difference between changing a transformer with a newer better one, and changing 30 ROE caps with new ones, the innards are no more original, but if you dont do the change you will have a not working unit, what I do is to keep the unit as close to original as possible and I would never do anything to change the performance or the design of the unit, but if I have a unit not working, I will do everything I can to get it working and looking like the original, I have used hours to keep my units working and looking that way. The way you are doing it, you will end up with 1 not working unit for each working unit you have, for me thats not the way to go, we have save all unit possible and as close to original as possible, but just scratch a unit to get get another one going is not the way to go. Sorry Bob, but I have to agree with Ablaumaise on this one, I just wish he had a name easier to spell Bob P.S. my ways aren't your ways ..... I only have 4 units (in 3 rooms) and 6 pairs of speakers apart from 2 Avant TV's, DVD1, bunch of remote controls, BG CD4500 (waiting to be re-united with BM4500), coming BG1202 and (yes I do have some spares for most of those, which aren't yet fully restored - to be used or passed on to new owner) I don't collect for the sake of it - I collect what I like use and appreciate on daily base - otherwise it'll be useless and won't enrich my life at all, there already are museums I take the time to source the units and original parts, and do recall many questioning why? (such S3702's) I already said - because is the only way; original and fully working 40years old system, and despite I rather enjoy reading ingenious ways to getting around and about fixing of the units - I wouldn't be very happy to own 1 for which I would have to alter diagrams ;)
P.S. my ways aren't your ways .....
I only have 4 units (in 3 rooms) and 6 pairs of speakers apart from 2 Avant TV's, DVD1, bunch of remote controls, BG CD4500 (waiting to be re-united with BM4500), coming BG1202 and (yes I do have some spares for most of those, which aren't yet fully restored - to be used or passed on to new owner) I don't collect for the sake of it - I collect what I like use and appreciate on daily base - otherwise it'll be useless and won't enrich my life at all, there already are museums
I take the time to source the units and original parts, and do recall many questioning why? (such S3702's) I already said - because is the only way; original and fully working 40years old system, and despite I rather enjoy reading ingenious ways to getting around and about fixing of the units - I wouldn't be very happy to own 1 for which I would have to alter diagrams ;)
Hi James:How clean is your AC power?I have a 9500 that had a loud humming transformer. I thought the thing had gone bad. Then I moved it to another location. No more noise.
Previously I lived in an old house with bad power.
Derek
If you want your original transformer rewound, I can recommend a workshop in Tel Aviv which does excellent work, at reasonable prices.
They have done BM3400 and BM4000 transformers for me in the past. Long-term use shows no hum at all.
There are very few transformer manufacturers left who can still work on the C-core transformers.
If interested contact me offline.
Regards
Menahem