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HI looking for the same blue cap as in the pic 120pf its out of a Marantz (pm66 KI)
the standard pm66 its a film cap.
is it a polystyrene cap? it looks like one inside
the original one burst open!
both output transistors and a 330r 2w resistor was blown on one channel
An externally hosted image should be here but it was not working when we last tested it.
MKT ? Maybe MKP, but I don't see any voltage rating. That seems odd.
I have NEVER seen a polystyrene like that.
I have NEVER seen a polystyrene like that.
wonder if these will do ?
2pcs - PHILIPS KP 120P (120pF 0.12nF) 630V 1% Axial Polypropylene Capacitor | eBay
2pcs - PHILIPS KP 120P (120pF 0.12nF) 630V 1% Axial Polypropylene Capacitor | eBay
Axial is not a good fit for the pin pitch. It looks like it might be 0.2", or 0.3"
You don't need 630V rating.
Look for much lower and the correct pin pitch. since 125V is quoted in the other post, try for 100V to 150V
MKP are available in 0.2" and 0.3" for these pF sizes.
You don't need 630V rating.
Look for much lower and the correct pin pitch. since 125V is quoted in the other post, try for 100V to 150V
MKP are available in 0.2" and 0.3" for these pF sizes.
These small caps are fitted across the pre-driver transistors, base to collector, of TO92 types 2SC2240 or 2SA970. They're there to shunt HF and RF from that gain stage, stabilizing and reducing the chances and severity of oscillation and RF breakthrough. There must have been some mighty oscillation in that channel or an accidental Mains short to cause that damage and I assume most of the transistors were toast.
They are stated in the KI version manual (rated 120V) as different to those in the SE version (rated 100V). I can't imagine there would be any real difference as the film thickness would not be altered for such a minor rating difference.
They are stated in the KI version manual (rated 120V) as different to those in the SE version (rated 100V). I can't imagine there would be any real difference as the film thickness would not be altered for such a minor rating difference.
That would make it an FKP.
The pic actually shows that it is foil and not metalised. My mistake.
I should have noticed and typed FKT or FKP.
I don't know if terephthalate (FKT) is available with foil.
The pic actually shows that it is foil and not metalised. My mistake.
I should have noticed and typed FKT or FKP.
I don't know if terephthalate (FKT) is available with foil.
Mon Capitain(e), Siemens-batit is Ceramic
[ Roederstein KP 1830 - Siemens KP B33063 - BC Components KP 374. All Film and Foil ]
[ Roederstein KP 1830 - Siemens KP B33063 - BC Components KP 374. All Film and Foil ]
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There is always some obscure example of every possible plastic film and metal foil combination. I haven't seen the type code FKT used though. This is Cornell-Dubilier type DMT.
An externally hosted image should be here but it was not working when we last tested it.
http://www.chambersamps.com/custom-built-amplifiers.html
Note: these guys supply the caps for "vintage tone" in guitar amps so you get the picture of what their audio qualities may be. Have a look at the other types in the brochure.
Broadly, Polyester caps of all types are used in DC applications while polypropylene types are kept for AC and pulse applications. Polyprop. has quite a bit lower DF than polyester and as Douglas Self points out, makes a much better audio cap if size isn't a problem.
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I have replaced all 4 output transistors, both reservoir caps,330r 2w resistor, and replaced the blue 120pf cap with a small ceramic disc and all is well and sounds very good indeed
will it be ok with the ceramic cap or should I go with polystyrene or film ?
will it be ok with the ceramic cap or should I go with polystyrene or film ?
if the ceramic is NP0/C0G and high enough voltage rating then leave it in.
If it is any of the HiK ceramics then take it out and replace with an FKP of the correct pin pitch.
If it is any of the HiK ceramics then take it out and replace with an FKP of the correct pin pitch.
struggling to find any had a look on RS CPC FARNELL MOUSER anyone know where I can get 120pf 120v FKP
They used to explode?
Don't they explode now?
Or did you mean, they use them to explode?
Tanatlum caps do have a nasty habit of exploding, but I don't think they make them that small. Fractional uF maybe, but not pF.
The only things that would cause film caps to explode are severe overvoltage or overheating. You'd never get enough current through that cap to overheat it - even if the amp were oscillating. In a 1kW RF transmitter, maybe. So it was probably just defective. Mica or high voltage ceramics can be used in that duty. Micas are a little lossy, but that will only help the stability concern. Z5U's are nonlinear wrt voltage, but the nonlinearity in a 500V cap at 125V will be far lower than the nonlinarity in the Cob of the transistor it parallels.
The only things that would cause film caps to explode are severe overvoltage or overheating. You'd never get enough current through that cap to overheat it - even if the amp were oscillating. In a 1kW RF transmitter, maybe. So it was probably just defective. Mica or high voltage ceramics can be used in that duty. Micas are a little lossy, but that will only help the stability concern. Z5U's are nonlinear wrt voltage, but the nonlinearity in a 500V cap at 125V will be far lower than the nonlinarity in the Cob of the transistor it parallels.
How many times do I have to type this, it's a BC Components KP capacitor.
Polypropylene film +foil.
Ken Ishiwata is a bling stylist !
They've been used in fancy Marantz + Philips CD/DAC gear since the late 1980s.
Example =>
Polypropylene film +foil.
Ken Ishiwata is a bling stylist !
They've been used in fancy Marantz + Philips CD/DAC gear since the late 1980s.
Example =>
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