Bang & Olufsen 2400

If Beomaster 2400, type 2901 a 15V supply to the bulbs is fed direct of the mains transformer. The AC to the main +/- 31V rails are via 2 relay contacts, relay powered from that 15V supply, is there +/- 31V at the main electrolytics and relay click over?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Yes relays click over . I took the relay cover off to check contacts & ok .

I did not check the 31 volt . Where ? on filters .

If i remember right i can hear a low thump in the speaker at power on but no music . The unit looks virgin .. very clean & nice .

Several common things with these.

1. The small bridge rectifier for the low voltage (+15?) has one diode o/c, and/or the filter cap has lost capacitance.

1. The lamps you changed must be 30-40mA, if more you can have trouble turning the unit off.

2. Check the center voltage of the outputs, just take the emitters of the four large transistors, must be close to 0V. If not, change caps and all semi in the affected output.Also check the solderings of the output transistors.

1. The red "ROE" capacitors has always been a problem, after 30 years you can expect at least half of them to e defective. I will sugegst to change them all. Standard values, you shold be able to get them all for a couple of dollars.

2. Check the bulb in the volume controller. If the bulb is o/c you will get no sound. It is a small square aluminiumbox with four LDRs and a bulb in the middle. You can check the bulb with an ohmmeter from the bottom, do not disassemble if not necessary!

1. One of the on/off switches (TR9) was often seen to be leaky. Change if strange on/off behaviour.

2. The Balance pot often goes o/c - can be bypassed by 4x10K resistor, or repaired mechanically, it is not so hard, but takes some creativity and patiience.

The above list should 90% + get your unit up running again.

Thanks Ole sounds like you are an expert on these . I will check all of those things .

Got it all fixed . It was a hand full of those red capacitors .First time i ever found bad capacitors in one of these B&O sets .

Thanks for the help