other than replacing tubes I am kind of "lost" on any repair, but was wondering if anybody might know what caused my radio to break. I have an RCA 1958 twin speaker table top radio. It's been recapped and was working well. I had it on the other day, and it let out a loud squeel and smoked. I turned it off and looked under the chassis. 2 resistors had burned up that were tied into the 35W4 tube socket (this radio uses the standard 5 tubes) Anyway... I tested the tubes and they were all good. So what do you think might have failed to cause this to happen? I've never had a resistor burn up in a radio or tv before. Do they just get old and fail or does something cause them to fail??

not an intellegent awnser but...

My electronics instructor always says that its wrong saying that things are run by electrons, they are run by smoke!... Have you ever seen an electron? no. but everytime something smokes it stops working doesnt it! all the smoke escaped it doesnt work anymore :D

Oh, and if they burned up, that means that they probbly were fed too much current. Check the voltages if you have a schematic. At least that would be a good place to start.

I know you said you recapped it, but that kinda sounds like a faulty cap to me. Maybe it was a borderline defective one that finally went out, let too much of a jolt through in the wrong place. Either that, or a wire got bumped into the wrong place and sent power current into the audio stage. That's at least two good possibilities to check, I don't know for sure...

A resistor always lets out its smoke because of an overload or short. Caps that are connected to a resistor are a good suspect but maybe not here as you re-capped it. Can you describe in more detail what the resistors connect to? I wonder if maybe there was a heater-cathode short in a tube that somehow caused this...that may not always show up on the tube tester.

I lean toward Chad's idea.

Did you hear a loud pop sound at the time this happened ?

What pin(s) were the resistors that cratered connected to on the tube?

I have an ASL AQ1003DT AMP which was connected to a pair of Klipsch KLF30s and had an EL34 short out. It sounded exactly like the sound of my wife stepping outside and "closing" the door after discovering the trifling cost of some of my audio upgrades :rolleyes:

Thankfully we have a motorhome !

As others mentioned, cathode/heater intermittent short, or caps: I would suspect the cap that couples 1st audio tube to the output tube, and the electrolytics. When replacing the resistors, be sure to use the same or next higher wattage rating than the originals. Also check the primary of the output tranformer for a short between wires or from a wire to the frame.

Reece

i'll have to get into it and look. I'm not to "with it" other than changing tubes. It did not let out a loud pop. I heard a loud squeel and could smell the smoke. I quickly turned it off and unplugged it. Tested the tubes to see if the 35W4 shorted. It still tested fine. This radio was an eBay purchase awhile back. l could tell from looking that it had been re-capped. Most of my old radios have been sent off and restored by Ray Bintliff. Cost runs pretty high (more than the radio is probably worth) but he does a great job. A few others (such as this one) were working when I got em' but are probably a ticking time bomb concerning the caps...

There could be a short in other tubes such as the 12AV6 or 5OC5. Check where the other end of the burned resistors connect to.
You might try to get a schematic (most of these type radios are pretty similar in circuitry) and see exactly where the bad resistors connect in the circuit.

Some caps that are more modern paper caps (plastic encased) (early 1960's era) will look more modern but still suffer the paper cap degradation. I would go ahead and re-cap with brand new mylar caps.