capacitor replacement type - Page 1
Forum section: electronics / projects

author: Crambone
author_rank: Frequent Contributor
timestamp: July 18, 2020, 11:02:23 pm
content: I'm looking for the following 2 capacitors but I'm unable to locate is there some other type I could use or anywhere I can find them?1) .0056 mfd 125V 5% POLY2) .0062 mfd 500V 5% POLY

author: TimFox
author_rank: Super Contributor
timestamp: July 18, 2020, 11:09:53 pm
content: "Poly" is an insufficient description. Do you mean polyester (polyethylene terephthalate or Mylar), polypropylene, polystyrene, polysulfone, or some other plastic film?Polypropylene is a good choice, if you have the space, and can be had in 5% tolerance. Polyester is a common choice for non-critical applications, but usually has a broader tolerance.Try the search engine at a distributor, for examplehttps://www.mouser.com/Passive-Components/Capacitors/Film-Capacitors/_/N-9x371?P=1yznbzsZ1z0wppwZ1yx4atuZ1yzs9nvfor a 5.6 nF, 5% polypropylene capacitor. You will have to choose a different working voltage: what DC voltage is actually present in the circuit? If you don't know, then go higher. Do not search with the obsolete term "mfd", since the modern meaning of "mfd" (millifarad) is 1000 times higher than what you want (microfarad).

author: bdunham7
author_rank: Super Contributor
timestamp: July 18, 2020, 11:25:43 pm
content: Quote from: Crambone on July 18, 2020, 11:02:23 pmIt would help to know what they are for, but try looking for 5600pF and 6200pF (or thereabouts--in many applications a little more won't matter).

author: Crambone
author_rank: Frequent Contributor
timestamp: July 18, 2020, 11:47:02 pm
content: They are for a Sencore TC162 tube tester

author: H713
author_rank: Regular Contributor
timestamp: July 19, 2020, 05:22:27 am
content: You might not find 125V and 500V parts, but you can probably find higher voltage rated parts. For 6.2 nF (same as .0062 mfd), Digikey only has 1.6 kV rated parts. That will be just fine. 5.6 nF they had 400V parts.

author: floobydust
author_rank: Super Contributor
timestamp: July 19, 2020, 06:13:33 am
content: They look like polystyrene which are mostly gone nowadays. Mouser sells them as Xicon brand, but are low voltage 50V and 0.005uF or 0.0068uF offered.In the Sencore TC162 Mighty Mite I see them for a neon lamp oscillator off 90VAC, guessing at least 160-250VDC parts are needed there.Common are polypropylene high voltage film caps 1.25-2kVDC so they are a bit big. It depends on what can fit the lead spacing on your board.Parts with long leads Panasonic ECWH series, consider Digi-Key Part NumberP15430-ND, ECW-HA3C622H CAP PP FILM 6,200pF 3% 1.6kVDCP10479-ND,ECW-H12562JVCAP PP FILM 5,600pF 5% 1.25kVDC 18mm with 15mm lead spacing and plump.I think these could fit. The 50uF 50V electrolytic cap will surely need to be replaced as well.edit: I see pics of another repair, the guy replaced the 0.01uF ceramic disc caps on the board.Other hard to find partshttps://www.justradios.com/

author: H713
author_rank: Regular Contributor
timestamp: July 19, 2020, 09:46:53 am
content: I hate to ask, but why are you replacing them? Poly caps rarely ever fail.Lots of people go through and blindly "recap everything!!!11", and in many cases do more harm than good.

author: Gyro
author_rank: Super Contributor
timestamp: July 19, 2020, 10:10:45 am
content: Quote from: Crambone on July 18, 2020, 11:47:02 pmPolystyrene caps don't have any significant 'wear-out' modes, they are close tolerance and film and foil construction, so don't suffer loss of capacitance through self healing like metalized film ones.

author: Crambone
author_rank: Frequent Contributor
timestamp: July 19, 2020, 12:41:11 pm
content: The tester was given to me and they are missing from the board. I tested the transformer and it’s solid so I figured I would try to bring it back to life. All the resisters and diodes checked good. The R21 & R22 variables aren’t stock but seem ok.