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Two defective Beomaster 1900s

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Mkickert
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Mkickert posted on Tue, Feb 26 2013 4:31 PM

Hi there, first post here!

A while ago I have bought myself a Beomaster 1900. Having not tested it myself I found that when it arrived it was, of course, broken (looking at this forum this happens more often :).

Originally the left speaker channel didn't work, and most of the lamps were out. Upon opening the unit I saw that the caps all had the dreaded yellow pest.

So I did the logical thing and got Martin's revival kit (caps and lamps). For all of those that haven't gotten it yet: do so! It is very competitively priced and the instructions are excellent. I cannot recommend it highly enough.

So using that I fixed it, and it worked brilliantly for half a year. However, recently it developed a very nasty hum after being on for a while.

With Martin's advice I also replaced the bridge rectifier (on the main circuit board near the huge cap) and the rectifier near the heatsink on the back. However the hum was still there, and it was having a hard time starting up. To add injury to insult to injury, during testing I did accidentally touch the two fuseholders for the main live. Apart from it stinging a bit and blowing the fuses, the problem remained. Very hard to start up, and a strong hum.

So having decided that one was decidedly dead, I bought myself a working 1900-2. My thoughts were to replace the touchpad cover and slider tabs with the 1900 one (which simply looks better), and then I'd have a pretty Beomaster 1900 with a better volume control. I tested it this time, of course, and apart from a few bad lamps (which I since all replaced with the correct 12v 1w lamps) it worked fine!

That is, until I left it running for half an hour and the unit instantly switched itself to channel 2 and wouldn't come off that again. Bumhats.

So now I have two broken Beomasters: one that has been completely recapped that won't turn on anymore. And one that is original (apart from the lamps) but switches channels on it's own.

What do you guys think would be the best course of action. Are they both saveble? Should I combine the two into one working one (there's no way I'm going to unsolder and then resolder all the new caps form the 1900 to the 1900-2). I'd love to hear your thoughts.

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Dillen
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Dillen replied on Tue, Feb 26 2013 5:13 PM

First one; Replace trimmers and adjust idle currents.
Second one; Replace rectifier (and eventually caps).

Martin

holger_holland
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These are the light bulbs specs for BeoMaster 1900 / 2400 en 2400-2:

Amperage: 80 mA

 

Voltage: 12 Volt

Wattage: 0,96 Watt

Fitting: T1 1/2

They are called micro lamps and you need 15 of them

You can order all over the internet so no need to buy an overprized 'special' lamp kit

Dillen
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Dillen replied on Tue, Feb 26 2013 6:15 PM

Unfortunately, most service manuals give out wrong specs.
12V lamps will be overrun and will only last very few hours.
You can buy the types made for chinese toys very cheap everywhere if you go for 12V types, they are
often found at less than 1 euro a piece (plus postage).
Alternatively I can supply correct longlife types like the originals at the mere cost of production and postage
but the choice of what to fit in your Beomaster is yours completely. Smile

Martin

Søren Mexico
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I had the same failures in my BM 2400, so go for the total, caps, lamps, trimmers and rectifiers, and check the sliders for correct functions. And all from Martin, easier, and you get the right items.

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

Mkickert
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Ah, bother. I replaced the lamps in the 1900-2 with (albeit good quality and rather expensive) 12V 1w lamps, as suggested in the original service manual by Bang & Olufsen themselves. Strange they don't get their own numbers right. They work great though!

Martin: I'll send you a mail for the parts.

Mkickert
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Alas Martin; to test your suggestion I just placed the (known good, in fact you supplied it to me only a few months ago) rectifier (near the fuse and C92) from the 1900 to the 1900-2 and the 1900-2 is still instantly switching its own channels. Could it be an other fault?

Dillen
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Dillen replied on Tue, Feb 26 2013 7:49 PM

Mkickert:

Alas Martin; to test your suggestion I just placed the (known good, in fact you supplied it to me only a few months ago) rectifier (near the fuse and C92) from the 1900 to the 1900-2 and the 1900-2 is still instantly switching its own channels. Could it be an other fault?

Easily.
A bad capacitor somewhere causing ripple or some other kind of instability.

Martin

Mkickert
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Ah, as with all things of beauty they have a mind of their own. Fickle little things.

Mail sent about the parts, anyway.

Mkickert
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Mkickert replied on Mon, Mar 11 2013 12:15 PM

Update!

I just spent a few hours last night recapping the 1900-2 (which went a lot faster than the first time).

However, powering it up today still no cigar. The unit hums heavily and still switches to channel 2 for no good reason. I checked polarity thoroughly on all caps, replaced the voltage rectifier and all lamps. Just the trimmers are left to do. Which reminds me Martin: do you have a diagram of which trimmers need to be replaced and to which value they need to be set? I didn't find any clues to this in your lovely revision set.

The other Beomaster, the 1900, refuses to switch on at all. No relais click, no glory.

I'm starting to get a bit disheartened with the both of them. But I won't let them win this battle!

Does anyone at all have any clue what might help?

 

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