What kind of Capacitor is this?

Not something I have ever seen before! Came from a Pioneer amplifier. The schematic is not really readable but a capacitor with 3 legs?
 

Attachments

  • IMG_20210717_001746849.jpg
    IMG_20210717_001746849.jpg
    244.4 KB · Views: 401
  • IMG_20210717_001758077.jpg
    IMG_20210717_001758077.jpg
    278.2 KB · Views: 378
  • IMG_20210717_001825208.jpg
    IMG_20210717_001825208.jpg
    219.1 KB · Views: 394
Why not?
Dual mount possible, radial or axial.

I am quite certain 1 of the radial pins is connected to case, DID you check for continuity with th main case one? 😀

Pinout might also indicate a dual capacitor, but in this particular case labelling does not support that.

Very popular in the old Tube era.

c-em33-33-450_0.png


products-C-HGE-5050-500.jpg


Grandpa 😉 :
SpragueAtom-1024x612.jpg


Similar but with tabs instead of wires:
ca3f6d345bb6ee64238e45f5ccc19924.jpg
 
Last edited:
How about giving us the Pioneer model number and let those of us curious enough to want to research it, have some way of checking what it really is. My suggestion is a non-polarised signal cap with isolated, grounded case acting as a shield- just because its about the only reason anyone would have for this type of product in an audio amplifier.
 
It is a capacitransistor! LOL

I measured it with my multimeter the pins at the bottom and top there is only 0.8uf of capacitance between each leg and only between the bottom pins around 470uf.

I measured many time, it seems the top is just for shielding...?
 
Well, I must admit that I have never seen such capacitor in my electronics life. Probably Nippon Chemi-Con made them just for Pioneer. :scratch:

Edit: clearly it's not bipolar. The minus markings are there.
 
Last edited:
Noise shielding, in the old days the shield was a grounding method.
Note there is a dotted cross on the schematic next to it, so it is special, to be noted, and so on. There may be details about it in the parts list in the service manual.

You might remember that on TV tuners, there was a shield to protect from stray signals, in the form of a metal housing which was connected to ground.
This could be similar, possibly connected to supply ground with some isolation device, our supply negative through a resistor, coil, somehow grounding the device to protect from stray signals.
We used to see small through hole capacitors for RF use, there was a round ring which was to be soldered to the hole in the shield it passed through.

You can put a thick copper foil, or anything similar as a shield, after replacing, if needed, if you use a standard capacitor, connect the shield to ground.
If the chassis is metal, and a three wire connection with earth is available, then ground the chassis, put a standard capacitor, i don't think shielding will be needed then.


A similar method is followed now, one sees this in multi layer PCBs, one layer being used as a ground plane.
 
Last edited: