I recently purchased this solid-state radio at an auction. The filter capacitor will need to be replaced. When I opened it up, I noticed an unusual "2 in 1" capacitor that has a "dummy" connection. One connection is 135 uF at 150V, the dummy connection, and common.

I measured the voltage at the dummy connection, and it was measuring 1VDC. The large capacitor was measuing around 75VDC (unusually large for a solid-state radio). What is the purpose of this dummy capacitor? Thanks in advance for your assistance.

:I recently purchased this solid-state radio at an auction. The filter capacitor will need to be replaced. When I opened it up, I noticed an unusual "2 in 1" capacitor that has a "dummy" connection. One connection is 135 uF at 150V, the dummy connection, and common.
:
:I measured the voltage at the dummy connection, and it was measuring 1VDC. The large capacitor was measuing around 75VDC (unusually large for a solid-state radio). What is the purpose of this dummy capacitor? Thanks in advance for your assistance.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mark:
I was initially thinking of that capacitor being a
plastic encased unit PCB mounted unit that would have a 3rd unused pin that RCA used. Researching the schematic revealed that electrolytic to be the common black cardboard insulated aluminun can electrolytic.
Near the terminals should be the typical square, triangle, bar and blank markings to ID the different sections.Usually they don't bring out terminals
on the unused sections but I think that you might have encountered that situation one time here. I feel the 1
Volt reading that you are getting is just a static voltage and is leakage from the adjacentfunctional section. The reason for the higher than normal voltage in one section of the radio....e.g. the audio output stage..... seems to be the old tube mentality of the use of a hi Z A.F. output transformer and its companion high voltage driven output transistor. Your voltage readings are in spec for that outputs B+ supply.
73's de Edd

Edd,
Thanks so much for your reply. I played the radio last night in an electronics class I teach; the students heard what happens when power supply filter capacitors go bad.

Thanks again,
Mark

::I recently purchased this solid-state radio at an auction. The filter capacitor will need to be replaced. When I opened it up, I noticed an unusual "2 in 1" capacitor that has a "dummy" connection. One connection is 135 uF at 150V, the dummy connection, and common.
::
::I measured the voltage at the dummy connection, and it was measuring 1VDC. The large capacitor was measuing around 75VDC (unusually large for a solid-state radio). What is the purpose of this dummy capacitor? Thanks in advance for your assistance.
:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:Mark:
:I was initially thinking of that capacitor being a
:plastic encased unit PCB mounted unit that would have a 3rd unused pin that RCA used. Researching the schematic revealed that electrolytic to be the common black cardboard insulated aluminun can electrolytic.
:Near the terminals should be the typical square, triangle, bar and blank markings to ID the different sections.Usually they don't bring out terminals
:on the unused sections but I think that you might have encountered that situation one time here. I feel the 1
:Volt reading that you are getting is just a static voltage and is leakage from the adjacentfunctional section. The reason for the higher than normal voltage in one section of the radio....e.g. the audio output stage..... seems to be the old tube mentality of the use of a hi Z A.F. output transformer and its companion high voltage driven output transistor. Your voltage readings are in spec for that outputs B+ supply.
:73's de Edd