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Beolover SyncDrive: DC Platter Motor Replacement for Beogram 4002 and 4004 (Type 551x and 552x)

Late Beogram 4002 and the 4004 (Types 551x and 552x), which have DC platter motors instead of the earlier synchronous AC motors usually suff...

Tuesday, September 20, 2011

Beomaster 8000 No-Load Current vs. Time II

After I installed the reservoir caps, I adjusted the no load trimmers one more time. Since the previous voltage vs. time measurements yielded a different behavior in each channel (left changed a few more mV than the right channel), I came to the conclusion, that adjustment in cold condition does not make much sense. I repeated this experiment a second time. This time, I waited the prescribed 30 sec after cold start and set the trimmers to yield 18 mV in both channels. Then I let the BM run for about 1 hr at zero volume setting. After the hour I measured a constant 25.3 mV in the left channel, and 22.4 mV in the right channel. The heat sink on the left channel was very slightly hotter reflecting the higher power consumption.
I thought, both channels should have the same condition under steady state operation conditions. Therefore, I decided to set the left channel trimmer that the no-load voltage would also be about 22.4 mV. This means of course that right after turn on this channel will run at a too low voltage (maybe 16 mV). However, since it took only about 3 min for the voltage to rise 3 mV in each channel after turn on, I do not think this poses any problem.

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