Westinghouse h251-Arcing 5u4

[fsjonsey]

I brought home a good condition Westinghouse h251 from a junk store today. I paid a whole $20 for it. I tested every tube and looked for any burned resistors or capacitors. One 5u4 was bad, so i replaced it. I hooked the set up to an isolation transformer and brought it up. The 5u4 i replaced started arcing internally. I quickly turned off the isolation transformer, and looked at the tube socket. There was no evidence of arching. One electrolytic can was extremely warm. Could my problem lie in a shorted filter cap? To be clear, I am going recap the entire set. I just want to make sure it isn't something like a shorted power transformer winding before i start putting effort into it.

[3Guncolor]

If the can is hot it is bad.

[jpdylon]

yup. 9 out of 10 times filter caps dry up and short --causing that arcing in the LV rectifier. It WILL become a shorted winding in your transformer if you continue to try to power up with that bad cap.

Generally any set of that age should be re-capped before trying to power it up. I check the tranny windings and fly for shorts. If they're good then i re-cap and go from there.

[Adam]

I had a 5U4 do that once, it turned out to be a shorted filter cap like you said. When it happened to me the arcing also did in the new 5U4 and I needed to get a 2nd replacement.

[Tubejunke]

Both of my RCA's of late 40's vintage did exactly this. One was cured with all new filter caps, the other ened up being a transformer replacement and cap replacement. The transformer was probably taken out by the shorted caps. I learned a lot of good lessons with the two RCA's. I will add that I never had this problem with other old sets with tube rectifiers. Now I have had a couple of sets to blow selenium rectifiers left and right.

I have played around with old TV's for over 20 years with a few long gaps of disinterest. When I was younger I ran across a lot of vintage sets that could be plugged right in without much power supply trouble. Most of the time I would power up a set and after a while some other (probably paper) cap would soon go out. I guess in the last few years the sheer age of the electrolytics is becoming way more apparent and I'm running into more trouble. Really I'm glad because it has allowed me to expand my troubleshooting abilities and general knowledge about how a given circuit works. For many years I was more of a tube or resistor changer that did a real good job of cleaning up chassis and cabinet for apearance. In the beginning I just preferred 50's sets for everyday use because you could still find a lot of working examples pretty cheap at thrift stores.

By the early 1980s most of America had achieved the attitude that color television was a birthright, kind of like kids look at remote control now. So at that time older black and white sets were hitting the curb and junk stores bigtime. Not long ago I tried to give a poor family a 19" color set for their son's room. The mother told me not to bother bringing the set because he had to have remote control. Really I don't know if it was the kid or the mother that decided that it would be better to have nothing than something that might be a bit inconvienient. Yes, the set had a turret tuner.

What cruel and unusual punishment it was when I was a kid having to get up to change a channel!! Just kidding. Actually I think we were perfectly happy with our 4 or 5 "air" channels, and also glad to own ONE family television. Color was icing on the cake. Have things changed THAT much?

[fsjonsey]

I'm just really hoping that the "electronics expert" that prices the stuff at this store didn't do the exact same thing I did, execpt for a much longer period of time. The 5u4 was blown already when I got it home. It had a "does not work" sticker on it.