ReVox B251 Power supply problem
Verfasst: Mittwoch 30. September 2020, 10:11
Hello everybody!
I am an enthusiast repair person. I mainly fix old Marantz units (22--).
Recently I bought a nonworking ReVox B251 - very interesting unit! I recapped all boards. That went fine, but I think I have a problem with the power supply. And since this is new for me, I decided to ask for advise from you, guys.
The problem is the following: when the blue wire of the right channel is connected to the power amplifier board, the B251 is acting strange - no sound from the right channel, buttons/lamps do not work, or light constantly on, etc. When disconnected, the amplifier acts normal - left channel is ok, buttons function, etc. If I switch the the left channel supply to the right channel, again everything is ok. I have replaced C11-C17 and C9 + C10 at the power supply board.
I have also measured voltages coming to the power amp and they are as follows:
Left channel: Unit turned off Unit turned on
Red 56,3 v 61,7v
Blue -56,6 v -62,8 v
Gray, Or, Blk 0 v 0 v
Right channel: Unit turned off Unit turned on
Red 56,5 v 66 v
Blue -56,5 v -56 v
Brown, Gray2 0 v 0 v
Gray 1 3,4 v 5 v
What I can also see is that T2 and T3 at the power supply have melted.
Tha main filter cap also tested ok.
So my question is: what might the problem be? Are these voltages ok, since the schematic gives +\- 55 v.
Any ideas and information is welcome!
Thanks in advance!
I am an enthusiast repair person. I mainly fix old Marantz units (22--).
Recently I bought a nonworking ReVox B251 - very interesting unit! I recapped all boards. That went fine, but I think I have a problem with the power supply. And since this is new for me, I decided to ask for advise from you, guys.
The problem is the following: when the blue wire of the right channel is connected to the power amplifier board, the B251 is acting strange - no sound from the right channel, buttons/lamps do not work, or light constantly on, etc. When disconnected, the amplifier acts normal - left channel is ok, buttons function, etc. If I switch the the left channel supply to the right channel, again everything is ok. I have replaced C11-C17 and C9 + C10 at the power supply board.
I have also measured voltages coming to the power amp and they are as follows:
Left channel: Unit turned off Unit turned on
Red 56,3 v 61,7v
Blue -56,6 v -62,8 v
Gray, Or, Blk 0 v 0 v
Right channel: Unit turned off Unit turned on
Red 56,5 v 66 v
Blue -56,5 v -56 v
Brown, Gray2 0 v 0 v
Gray 1 3,4 v 5 v
What I can also see is that T2 and T3 at the power supply have melted.
Tha main filter cap also tested ok.
So my question is: what might the problem be? Are these voltages ok, since the schematic gives +\- 55 v.
Any ideas and information is welcome!
Thanks in advance!