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Bellari RP562 hum

Posted: Mon Jun 26, 2017 2:32 am
by ECC82
Encountered the following problem: when increasing the Bottom knob volume there is also an increase in hum. Problem could be that the transformers are to close to the mainboard. Someone here who cured that problem?

73'
Chris
PA3TVI

Posted: Sun Oct 29, 2017 9:25 am
by Voodoo Guru
Howdy Chris,
More then likely the problem is with the filter capacitors in the low voltage +-15V power supply. This is a common problem with the Bellari equipment. We have also had problems with the voltage regulator transistor in the high voltage power supply creating hum and noise.

Good Luck!

Posted: Thu Nov 02, 2017 11:24 am
by ECC82
Thanks, Voodoo Guru. I will certainly try to cure this problem. Think the Panasonic FC caps will bring improvement. Will have to check how many and what Pf/voltage is needed.