Wax capacitors

[Dorian27]

I have 3 wax capacitors I want to replace but not sure what to replace with they are:-

0.02uF 750VDC
0.01uF 1000VDC
0.005uF 1000VDC

Can any one help with what replacement values and voltage please?

Thanks.

[Station X]

Take a look at this thread:-

https://www.vintage-radio.net/forum/...ad.php?t=88767

[AdrianH]

Without everyone knowing what the application is and where in the circuit they are then one can only suggest the same voltages and values, 0.0047 will probably do for the 0.005 and 0.022 for the 0.02 you have.

CPC have a range of caps over 1000 Volts but no 10nF in stock at the moment.
https://cpc.farnell.com/w/c/electron...e=inc-in-stock

Perhaps Farnell, RS or even Ebay may be a way forward.

Adrian

[DMcMahon]

Any modern good quality type would be suitable generally, I personally prefer Polypropylene Metallized Film, often yellow.

David

[Restoration73]

These are probably decoupling, HV ceramics are ideal and cheap;

https://cpc.farnell.com/multicomp-pr...y5p/dp/CA08718

[Silicon]

High voltage waxies were sometimes used across the primary of the output transformer or across the mains.

[DrStrangelove]

Originally Posted by Silicon

High voltage waxies were sometimes used across the primary of the output transformer or across the mains.

Oh yes, the exploding wax mains filter capacitors of yore.

They really woke you up.

I had one of those go off about 10 years ago.

It tripped the RCD on the bench as it went.

[dougietamson]

When sourcing hard to find parts you can connect eg 2 x 22nF/1000v parts in series for 11nF (bonus is voltage rating doubles). For parallel connection the capacitance doubles, eg 2 x 22nF doubles to 44nF and voltage rating stays at 1000v.
Use an online capacitance series/parallel calculator if using dissimilar capacitances.

[stevehertz]

Just look for those values of capacitance coupled with voltages the same as or higher at Cricklewood Electronics. I have dealt with them for years; fast, efficient and decent on price, oh and good quality caps.

https://www.cricklewoodelectronics.c...-to-1000V.html

The point being, it's generally only when you get down to small pF values that the actual 'spot on' value is important. So, in this instance, 0.022uF is perfectly good for 0.02uF, and 0.0047uF is good for 0.005uF.

[Radio Wrangler]

You haven't said what they're for. If they're used in mains filtering, then there are safety concerns. 1000v waxies were once used for these tasks. There are special grades nowadays for these uses.

David

[Philips210]

Originally Posted by DrStrangelove

Oh yes, the exploding wax mains filter capacitors of yore.

They really woke you up.

I had one of those go off about 10 years ago.

It tripped the RCD on the bench as it went.

I remember a Bush DAC10 that I purchased from a chap that often had a selection of vintage equipment for sale. I tried to tell him not to connect long dormant old radios etc to the mains because of the risk of exploding electros and mains filter caps but he wouldn't listen. The DAC10 had been 'tested' by him. On opening it and giving it a quick check, I noticed the waxed paper mains filter cap and blown out with quite some force. There was an empty case with the guts up against the chassis and small molten globules of aluminium stuck to the chassis around the blast zone. It must have been quite a deafening bang!

Regards,
Symon

[Philips210]

I generally use axial lead polypropylene caps as replacements but decent quality polyester film caps are also good. The Mullard mustard caps are also decent parts to use.
For the mains filter cap, a Class X2 type is recommended but a 1000Vdc rated polypropylene type is a good safe alternative.

Regards,
Symon

[Craig Sawyers]

I restored the Lorenz SZ42 cipher machine at Bletchley maybe 15 years ago. It hadn't run since it was captured during the late days of WW2, so it was a red letter day when it started running again.

Then after a few minutes - bang!

The drive motor had a CLC filter to stop commutator noise getting onto the power lines, which also fed sensitive receivers.

The capacitors had blown.

Of course the filter box was pitch filled. Melting that out gave enough information regarding the capacitor values, which I replaced with the correct X2/Y1 grade modern components, then filled back up with pitch. That sorted it!

Craig