Need Help Tracking Down a Cap for My CJ PV8 – 20 µF, 400V AC, 800V DC

[Ignaciog]

Hey folks on AudiKarma,
I’m diving into fixing up my old Conrad-Johnson PV8 preamp, and I’ve hit a snag. The fuse keeps blowing, and after checking the tubes (all good—12AX7s, 5751, and 5965s, no shorts or issues on my multimeter...) , I zeroed in on a capacitor that’s acting up. It’s the big black one near the power transformer, and here’s what’s written on it:

• Markings: “PPE 2000MKP 0X 20 uF + 5% 400V AC 800V CC JRFPU 11.87”
• Specs: 20 µF, ±5% tolerance, 400V AC, 800V DC (I think “CC” means Continuous Current/DC), metallized polypropylene (MKP), non-polarized.
• Size: Axial, cylindrical, black, about 1–2 inches long, 0.5–1 inch wide, with leads spaced around 0.5–1 inch apart to fit the PV8 PCB.

This cap seems to be the power supply one, filtering the B+ (around 200–300V DC), and it’s showing leakage—856 kΩ on Resistance Mode and 1.013V on Diode Mode. I’m pretty sure it’s why my fuse 0.75A keeps popping. I’ve been trying to track down a replacement but can’t find an exact match for “PPE 2000MKP.” I’ve looked at Mouser, Digi-Key, eBay, JustRadios, and TubesAndMore, but no luck so far.

 

[Ignaciog]

i found this : https://www.vishay.com/docs/26015/mkp1848cdclink.pdf
Does this look like a good replacement?

Thanks guys

 

[Oasis8]

If It's filtering the B+ (around 200–300V DC) you don't need a 800vdc cap.

A 400vdc Solen PB would do. These are very nice in PS duties.

Solen 20uF 400V Polypropylene Capacitor

Solen 20uF 400V Polypropylene CapacitorThe exceptional Solen line of metallized polypropylene capacitors features a high purity, polypropylene film dielectric. They exhibit outstanding high frequency characteristics, low dielectric absorption factor, high current capacity, and unrivalled...

www.parts-express.com

 

[Ignaciog]

Thanks Oasis,
Im confuse since the original capacitor shows

400V AC/800V DC​

I attach an image of my pv8 interior as reference, i circled the capacitors that shows leakage.

 

[Oasis8]

Yeah I'm not sure why they used such a high rated cap if it is only seeing 300vdc.

 

[ivandezande]

Thanks Oasis,
Im confuse since the original capacitor shows

400V AC/800V DC​

I attach an image of my pv8 interior as reference, i circled the capacitors that shows leakage.

Use the Solen linked above. If that one is having issues, you should replace them all (all the other black caps with that brand).