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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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