Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: J Rindt on March 21, 2017, 05:35:44 pm

Title: Qrange 120 caps
Post by: J Rindt on March 21, 2017, 05:35:44 pm: There are a few on the PCB also.
What kind of caps are these.?
I am changing all the power supply type caps.....Are these something that should be changed with the Elytics as well.?
Thank You
(are these polystyrene.?)

http://imgur.com/t5ytSkf (http://imgur.com/t5ytSkf)

http://imgur.com/3TKH2Xn (http://imgur.com/3TKH2Xn)
Title: Re: Qrange 120 caps
Post by: kagliostro on March 21, 2017, 06:04:15 pm: To me no, that kind of cap last for a very long time

they are film capacitors but I don't know exactly if polyestere or polistyrene or which other kind

Franco
Title: Re: Qrange 120 caps
Post by: pompeiisneaks on March 21, 2017, 06:58:52 pm: Those kind of caps only need to be changed if they are leaking DC. I can't recall the exact way to test this myself, something about removing one lead of the capacitor and putting a voltage across it and see if you measure DC on the other side, but someone here probably can give you the exact way to do that, otherwise you could read this:

http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html (http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html)

Which seems a bit more complex.

~Phil
Title: Re: Qrange 120 caps
Post by: FranciscoPerez on March 22, 2017, 12:05:57 pm: I'm pretty sure those are 160V styrene caps, and I never found one to leak.
They'll be most probably fine, I wouldn't change them.
Title: Re: Qrange 120 caps
Post by: J Rindt on March 22, 2017, 03:05:14 pm: 10-4.....Thanks for the help. :)
Title: Re: Qrange 120 caps
Post by: dross on March 24, 2017, 04:40:48 pm: Those are definitely Polystyrene caps. Just bought a bunch for a GT 120 I am slowly putting together.

They likely do not need replacing, and I hear that they are quite heat sensitive, so be gentle with the soldering iron.
Title: Re: Qrange 120 caps
Post by: J Rindt on March 24, 2017, 05:46:55 pm: OK.....i most likely will not need to get near them with an iron, but your warning is noted and filed for future use. :)