Bang & Olufsen 2400
 

Model 2400 low flat receiver . It powers on like its supposed to but has
no sound . The volume lights work properly . Other problem is it wont
turn off when i touch the off button , it has to be unplugged .

So far i have taken off all the covers and replaced any burned out bulbs
I have restored 5 of these with no trouble but cant figure out this
one

Thanks !

Bang & Olufsen 2400
 

Ken G. wrote in message
...
Model 2400 low flat receiver . It powers on like its supposed to but has
no sound . The volume lights work properly . Other problem is it wont
turn off when i touch the off button , it has to be unplugged .

So far i have taken off all the covers and replaced any burned out bulbs
I have restored 5 of these with no trouble but cant figure out this
one

Thanks !



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
http://home.graffiti.net/diverse:graffiti.net/

Bang & Olufsen 2400
 

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 .

Bang & Olufsen 2400
 

On Sat, 4 Feb 2006 09:14:07 -0700, (Ken G.) wrote:

Model 2400 low flat receiver . It powers on like its supposed to but has
no sound . The volume lights work properly . Other problem is it wont
turn off when i touch the off button , it has to be unplugged .

So far i have taken off all the covers and replaced any burned out bulbs
I have restored 5 of these with no trouble but cant figure out this
one

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.

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

3. 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.

4. 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.

5. 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!

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

7. 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.

Bang & Olufsen 2400
 

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

Bang & Olufsen 2400
 

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