Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: leevc5 on September 23, 2017, 06:14:37 pm

Title: 5F2a blowing 22/50V cap next to 5W cement resistor?
Post by: leevc5 on September 23, 2017, 06:14:37 pm

Plug it in, hear a humming sound then POP...smoke...capacitor debris all over the place.

What could it be?

Title: Re: 5F2a blowing 22/50V cap next to 5W cement resistor?
Post by: sluckey on September 23, 2017, 06:39:37 pm

A bad cap.

Title: Re: 5F2a blowing 22/50V cap next to 5W cement resistor?
Post by: labb on September 23, 2017, 07:36:45 pm

installed backwards.

Title: Re: 5F2a blowing 22/50V cap next to 5W cement resistor?
Post by: tubeswell on September 23, 2017, 11:50:35 pm

With polarised electrolytic caps, you need to observe the correct polarity. (+ve pole should point to the higher voltage end of the cathode resistor)

Title: Re: 5F2a blowing 22/50V cap next to 5W cement resistor?
Post by: shooter on September 24, 2017, 10:16:48 am

Voltage rating is the last thing not mentioned, I've blown up 1 cap when I got in a hurry and put a 350vdc where a 450vdc shoulda been :think1:

Title: Re: 5F2a blowing 22/50V cap next to 5W cement resistor?
Post by: 2deaf on September 24, 2017, 12:46:17 pm

Quote from: shooter on September 24, 2017, 10:16:48 am

Voltage rating is the last thing not mentioned, . . .

If the 5W cement resistor isn't performing its intended function, the 22/50V cap can charge up well past its voltage rating.