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Beomaster 2400, 3000, 4000.

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JFV
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JFV posted on Fri, Aug 23 2019 6:40 AM

Being very new to B&O products, I have been completely bitten by the sheer "magic" of the technical engineering of all the vintage products. I have aquired 4 turntables,5 amplifiers, 1 tape deck, Beocentre, of which some are in working and beautiful restored condition. Then I have multple Beomaster amplifiers, 1001,2400,3000, and 4000.

Coming from a electronics background I have repaired and restored only a few B&O amplifiers. I,m still getting aquainted with fault finding and repairs. I do have a scope that makes things much easier with signal gens etc. I own some of the above, that is 3000 and 4000 Beomaster as well as Beocentre my pride and joy, I also own a Beogram 4000, for me this is the ultimate, perfect working order, as well as 1202, 1203 beograms. Both amplifiers a 3000 and 4000,switch on but on the 3000 there is no stereo, and on the 4000 only one ch is working. I found the problem with the 4000, that was blowing the drivers on one ch, it was incorrectly wired. I'm still working on the 3000 that is not working on stereo. I have also started recapping the 2400 amps (2 of them). Both when switced on are either muting or fault switch is "operational" Starting from scratch how do you repair this fault. Surely if there is DC on the output it should first power up and then switch off? I have checked the drivers and they seem to be fine. If the output caps(3000 microF) are faulty and no speakers connected (using earphones) it should power up?. I havent checked the fault detector or muting circuit components, that is the next step. As you can see I have multiple projects at the moment and will be busy for quite a while with repairs and restorations. I'm totally bitten and am a B&O hoarder. Just love it and needless to say I'm having marriage problems tongue in the cheek! Needles to say I have found plenty of "tips" and advice on this forum.

Are there still spares available for Beogram 4000/6000 turntables. One of the faulty turntables I have, the microswitches are totally broken. I dont know how it happened but it has? Being in South Africa, certain spares are difficult obtainable. Fortunately I have contacts in Australia, but not in the UK or Finland for that matter.

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Beo_Jean
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QC, Canada
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Tackle one thing at the time I would say.

DC at the output is "normal" to a certain point but zero is always best.  It also depend on how the amp was built.  Some have coupling capacitors at the output in order to remove that DC while others don't.

There is also the deferential transistors to check, these are usually perfectly matched to remove DC from the output.  Shorted or blow output transistors, capacitors, resistors are all in the mix.

When working on a vintage amp, first I always recap then I check every single component.  It is time consuming but it works all the time. 

Good luck!

 

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