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Line voltage conversion Beolab 4000

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depe
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depe posted on Sun, Jan 3 2021 3:17 PM

Hi, 

I own Beolab 4000's with European specs (220V) but operate them with 110V line voltage (CAN). I currently use an external step-up transformer, which is ok but far away from being a clean setup.

Has anybody modified Beolab 4000 speakers and can advise how to do this? I have no problem with opening the speaker and solder stuff myself.

I had a quick look at the service manual. It appears that the standby transformers can be easily reconfigured for 110V by changing fuses (effectively changing the primary transformer windings from series to parallel circuit). 

The manual lists different part numbers for the main transformer. Acquiring a different transformer might be a show stopper. So the question is whether the same main transformer can be used for both 220V and 110V.

Any insight into this is appreciated. Thank you

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Keith Saunders
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Depending on your BeoLab 4000 type number and serial number it is possible you could be lucky.

As you will see from the circuit diagrams below its not just the different transformer, but also the addition of L1 inductor which was introduced into units from serial number 12893602. What is the type number of your units?


Regards Keith....

depe
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depe replied on Sun, Jan 3 2021 5:19 PM

Hi Keith, 

my units (I have two pairs) start with 14XXX and 18XXX. The type number is 6636. I guess it means that those are MK1 (which is good) and they have the white foam that does not rot (even better). 

Is my understanding correct that the standby transformer works for both voltages, given correct application of the fuses. What about the main transformer? Is is one model that fits all or do I need to replace those?

Thanks 

 

Keith Saunders
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You are correct it is a updated version of a Mark 1 which is an EU version which is exactly the same as the UK version except for the supplied mains cable which has the appropriate plug.

The main transformer does not change the primary windings, but takes half of the secondary as below


Regards Keith....

Keith Saunders
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The following transformer table may help you further in making your decision:-


Regards Keith....

depe
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depe replied on Sun, Jan 3 2021 8:02 PM

Hi Keith, 

thanks for the info. As suspected, the main transformer needs to be changed. At least according to the above table. Bummer. That could have been entirely avoided by the HW designer. Too bad.

pilza
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pilza replied on Sun, May 9 2021 4:48 PM

Hi Keith,

I am surprised that there is no info on generic standby transformer components that will work on the BL4000 as it seems such a common problem.

I have four MK1 UK BL4000s wo works (still) and others have stdy trafo gone and consequently fuses blown. The coil seems to wear out after many years of standing by.......

Fuses are easy to source generically, but the trafo I could not find the exact spec as the 8013582 # is for B&O parts catalog. Do you know which generic trafo spec will work? Surely RS components would have it as these are outsourced components (doubt BO make their own).

hope you can help.

Arno

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