Sound dead on TV, any ideas

I just got this email from my sister in which I will post her quotes directly. I think it's obvious something in the audio circuit fried in the TV but is there any particular common failure when this happens? The TV is just a simple 25-27" regular CRT TV, now quite a few years old.

" sat down briefly to eat some lunch and turned on the tv while munching. All of a sudden I heard a slight snap and the voice was gone. I dubbed with it trying to see what was wrong. I could not decide whether it was something to do with my Direct TV or the television, itself. The light bulb went on inside my head and I ran upstairs to turn on my little bedroom tv. I figured if I had sound there, it was the tv that was on the fritz and not Direct tv. Well, guess what??? The television voice comes on upstairs so it has to be in my RCA set...... Do you know what it might be internally? Do you think that it is a simple thing or is it just my luck.... the tv is dying? The picture comes in great! Can use the DVD player & VCR as long as I listen upstairs."

I'd say leave it unplugged over night and see what happens. Electronics play odd games and sometimes nothing more than time will fix things, if not permanently, temporarily at least.

Sounds like a cold solder joint on one of the sound circuits
You could try giving it a firm stiff whack on the side and see if the sound comes back on, or on the bottom. Not a hammer bash but like an open hand slap about a foot away from where you are hitting may get the sound back temporarily. If this works and goes out you will have to find the bad joint or take it into a repair shop.

There's a small button on the bottom rear of my TV that turns the sound off and on. Every once in a while my cat rubs against it and turns the sound off. Perhaps your sister's TV also has such a button. If so, press it. It might reset the circuit.

you said the magic word
rca
many sets with ctc 175-187 chassis had trouble with bad tuner wrap ground soldering.
this leads to a corrupted eeprom.
one symptom is muted sound.
bet it sometimes got a bit snowy and shrunken from the top.

If the set has a headphone jack, tap on it lightly with a ballpoint pen or insert & remove an appropriately sized plug a couple of times to exercise the contacts. I've seen some of those become intermittent.

She heard a snap before the sound went out. That indicates to me that something "blew" and it will require professional repair. Except that will likely cost more than the set is worth. Maybe there is an audio out connection on the TV that can be routed to a stereo. That will allow her to hear the sound that way.

Yeah, after I wrote that reply I was thinking about that 'snap' sound some more, and I suspect you're right - it was probably an electronic arc'ing sound or a teensy explosion. That's not likely to be a simple fix without the use of instrumentation.

You could always work backwards from the audio output stage using an audible signal injector, or if you can obtain a schematic, work forwards from the audio detector stage using an outboard audio amp as a tracer, but either way it's gonna require a hot soldering iron at some point.

Lurker has the right idea. But if the entire TV audio system is dead, there's one more thing to try.

She said it was DSS "Direct TV". Depending on the model of reciever it is, perhaps the Satelite box has AV outputs on the back as well, if so, she can run those through a stereo as a work-around, if the TV has the dreaded "not worth it" syndrome when it comes to repairs.

I had something similar a couple of years ago (with a 25 year old set, still working great) was one of the cables had physically come off the solder tab on the speaker itself. That made one heck of a "snap" when it came off, but reattatched it, and it's worked fine ever since.

<LECTURE> Just do bear in mind, that poking around inside a TV is NOT recommended at all unless you know EXACTLY what you're doing. There are voltages in there which are, in a simple word, LETHAL. Excuse all the caps, but I thought that someone really should point it out. TV's are dangerous things. </LECTURE>

I meant to post earlier but Saaby was right. Sis said she unplugged it and plugged it back in the next morning and all was well again. I too thought something had blown because she said she heard a snap. Wonder if there is some sort of resettable device that may be thermistor control or something to the effect that might have tripped.

It's possible that an audio IC simply latched up. The really high-impedance CMOS chips have a tendency to do that once in awhile if the circuitry isn't designed to suppress this phenomenon.

the snap may have been a hv arc .
this can cause glitches like you had.

dust it out.
it might make it last longer, if that was a high voltage snap, or a breaker that blew.