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Bang & Olufsen (B&O) Beomaster 2400-2 Problems
In , on 08/08/04
at 01:24 AM, (Paul) said:
Hi All,
I recently purchased a Beomaster 2400-2. The guy I purchased it of
assured me it was working fine, but when I got it home it was a
different story....
There seems to be a loud humming noise in the background, this seems
to be present on all the inputs as well as the radio. I plugged in a
set of headphones (thinking it might be the speaker outputs), but the
hum was still there.
I've not seen this in a 2400, but a similar model, the 1900 had a power
supply bridge diode problem. The diode would fail, sometimes after
playing OK for a while, and cause hum and problems with the touch pads.
It's easy enough to check if you have instruments. Look at the raw
output of the diode bridge and the bad diodes will show an asymmetric
waveform. (one of the peaks will be missing or much smaller than the
other)
You could also have a filter capacitor problem.
The other problem is with the radio...FM5 seems to work fine (despite
the hum) but all the other FM presets have no sound FM1 to FM4 (when I
turn up the volume to the maximum, I can hear them faintly)
I am just wondering if anyone has had any experience with these
systems?, and could describe what the problem may be.
I haven't had much technical experience, but I am adventurous with a
screwdriver and soldering iron.
I do recommend that you find someone who has experience with B&O and
have them fix it. I've seen a number of these units damaged beyond
repair by well meaning fixers who didn't have the imagination to deal
with something different.
For the most part, there seems to be one book that all the audio
designers read -- a long time ago. It's amazing, despite the marketing
hype, how similar all the units are. B&O units are different. Many
servicers are grumpy about having to learn something new when dealing
with B&O. The B&O physical designs are different and the manuals are
written differently. While I don't always agree with the B&O physical
design, their documentation is the best. (But, it is different and one
might need to study it for a few minutes before realizing how good it
is. Unfortunately, there are occasional language problems in the
English version.)
If you attack the unit yourself, take care when removing the touch
panel. Don't bend any of the metal tabs on the underside and, when you
reassemble the unit, make sure all of the tabs are locked on to their
matching metal post on the PC board below.
Also, when disassembling the unit far enough to replace the diode, pay
attention to the screws. There is one screw that you don't have to
remove, but you may think that it must be removed. You will regret
making that mistake. (nothing will be damaged, but you'll waste some
time recovering from the error)
If one of the lamps is out, replace *ALL* of the lamps on that PC
board.
Finally, unless you are fully equipped and experienced, don't mess with
the FM alignment. These tuners are a bit different and the alignment
instructions are not as helpful as they could be.
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