I recently received a nice condition Beogram 4002 (5513) for some TLC. So I opened it up and hooked it up to my Beosystem 6000 for a test drive. Immediately when I turned on the Beomaster 6000, a loud hum became apparent...I turned off and had a closer look. It turned out that P9 on PCB was inserted 180 degree reversed. That can happen since the 6 pin plug is not polarized, i.e. it can be inserted in both directions. Luckily, this is not damaging, since this plug does not carry any power rails. Here is a picture of the wrong orientation:
According to the circuit diagram the black chassis ground lead needs to be on the right side when observed from the front of the turntable. Like so:
This fixed the hum issue.
Further inspection also revealed a bit of a messy (but inconsequential) soldering job at the chassis GND connector at the back of the Beogram (I really wish people would spend a few minutes watching some of Norman Meir's absolutely excellent soldering tutorials on YouTube before messing with these beautiful vintage units...;-):
So far so good! I am listening to Somethin' Else (Blue Note 1595) on a nice 200g Classic Records audiophile reissue (stereo version) trying out the lovely, nice condition MMC6000 that this Beogram has fitted! Lucky owner!!
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