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Yes, I know I’ve recently have a similar problem, that I asked about here, but I found out. This is another unit and it’s not the same problem/fix. So:
I’m working on a Beomaster 2400 type 2901. Everything was working after I replaced a faulty potentiometer, but after replacing the main filter capacitors the unit developed a problem.
Current symptoms:
- Approximately 28–31 Ω between TP15 (15 V rail) and ground with the unit switched off.
- When powered on (even on a dim-bulb), the 15 V rail stays very low.
- As soon as I select an input (e.g. FM), the relay starts clicking continuously and the dim-bulb lights brightly.
What I have already checked / done:
- Replaced the two main filter capacitors (and later put the old ones back – no change).
- Replaced 2C92 and D50
- Replaced D55 (measured good out of circuit).
- Checked all electrolytic capacitors on the 15 V rail – they measure OK (most are new).
- Checked TR31 – measures OK.
- Checked the relay coil – OK.
- Disconnected the tuner board (after L1) – resistance only rose slightly to ~31 Ω. Tuner board itself measures ~500 Ω between its 15 V and ground.
- Checked D20 and the series 1 µF capacitor – both measure OK individually.
- Heat-tested solder joints around the 15 V area – no change.
- Output transistors are not shorted.
- TR14 has been checked (not shorted this time).
- Changed 70% of the electrolytics (most originals actually tested OK), and I have triple checked that all new ones are OK and mounted correctly.
I cannot find any component that measures ~28 Ω or lower between its pins, and I have not been able to locate a solder bridge.
Also worth noticing: the boards 4, 5 and 7 are disconnected.
Has anyone seen a similar low resistance on the 15 V rail (TP15 to ground) on a Beomaster 2400 / 1900? Any suggestions on where else to look would be very welcome.
Thanks in advance!
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