Hoffman AC30 electrolytic blew up

[Oddvar]

HI again. I was just finishing my Hoffman AC30 build, plugged it in, and after a few seconds the electrolytic capacitor besides the 50 ohm 10 w resistor blew up, creating a lot of smoke.  It was a 220 uf 100 volt cap.  What could possibly cause this I wonder?  The fuse didn't blow. V3 went all white at the top.

[tubenit]

Installed backwards?   Exceeded voltage rating?  Faulty cap? 

[Willabe]

V3 went all white at the top.

That tube lost it's vacuum, it's dead. The white is/was the silver colored getter.

[2deaf]

If the 50 ohm resister is not presenting any resistance in the circuit, the electrolytic will charge up until it explodes.  Exciting.  Check to be sure the cathodes have around 50 ohms to ground.

[bnwitt]

I never start up a new build without having it on a light bulb current limiter.  This can save a lot of destroyed components when something is faulty improperly valued or wired wrong:

https://www.youtube.com/watch?v=wRFRwOnLsZI

Barry

[PRR]

Bad EL84.

[shooter]

Bad EL84.

but as the cause, or another effect

[Oddvar]

Didn't see a an unsoldered ground from the board to the cpacitor that blew, bad work.  Now I have sound, but accompanied with a bad hum, the sound is low.  Gues I have som investigating to do...