OT: Tempermental electronics

[Baron Munchausen]

Ok, since we've got so many people with so many different backgrounds here maybe we've got someone who knows about electronics other than computers?

I've got a rather, uh, 'inexpensive' shelf stereo that's got a problem and I am wondering if it is something inherently wrong with the device or perhaps an outside influence. Every so often when I am listening to the radio function, and never at very high volume, it will give off a huge POP noise and stop producing any sound. Flipping around on the radio tuner I find that it simply doesn't turn out any sound. But the stations are still being received because I can see the 'stereo' light going on when it hits a strong station frequency. Turning it OFF and then ON again will restore it. Until it goes POP again... Flipping through the 'function' options, from radio to tape, AUX, CD player, and back to radio will 'sort of' restore it but then the volume is whacked out. It plays very fuzzy and loud as if the volume control is disconnected. Only turning it OFF and then ON again will really restore it. Yet, this doesn't seme to affect the other options. The CD player and AUX work fine even after the POP has discombobulated the radio function.

There is NO predictable pattern to this. It doesn't happen at regular intervals, it doesn't happen at a certain time (right after turning it on, only after running it for X hours) it just happens at random. Sometimes I can listen to it all day without this happening once. I've not (yet) identified any other events that seem to coincide with this, like the starting and stopping of major appliances, but it sure looks like an external event of some sort. Maybe my neighbor has a really noisy microwave oven? Could this be a malfunction in the radio? If so, are these things ever fixable anymore? Or worth fixing in a ~$150 consumer electronics bauble? Just curious if anyone recognizes this behavior as a clear sign of some identifiable problem.

[ June 23, 2004, 18:33: Message edited by: Baron Munchausen ]

[geoschmo]

Ya, you probably have a capacitor that is wearing out. Sometimes they will arc internally and short out and the only way to stop it is to cut the power which causes the charge to drain out of them.

It's probably temperature related as to why it happens exactly when it does. You could set it out in the sun for few hours and I'll bet it acts up a lot worse then normal. In the shop they'd stick it in a low oven for while, but kids, don't try that at home.

Finding the actual bad component will be next to impossible without popping the cover and checking voltages while the thing is acting up. For that you'd need a scematic diagram which you aren't likely to find for any radio built in our lifetime.

Edit: If the radio has sentimental value or something you might be able to find a little shop that will be able to fix it for less then buying a new one would cost. But not much less.

[ June 23, 2004, 18:56: Message edited by: geoschmo ]

[Baron Munchausen]

Well, it is now 100 percent dead. Worked fine for several days before it died. I thought maybe the problem had just 'gone away'... but then I turned it on this afternoon and pop and that was it. Turning it off and on again doesn't work anymore. There is no sound in any mode. So, I go back to Walmart where I bought it ( before I learned how evil Walmart is... ) and asked them about a return since it had been less than a year. It seems that this sort of product doesn't get exchanged if its past 90 days. It gets sent to the manufacturer for repair (or replacement, I suspect). Oh, joy... more customer service hassles with major corporations. So I guess I'll have to box it up and take it back soon. Then see how long it takes to get it back and how long it works after I get it back.

[dogscoff]

No idea what the law is over there but over here you can take any faulty item back to the point of purchase if it's less than 12 months old and INSIST on a refund/ replacement and they have to give it to you, legally. You don't even need a receipt. I've done this several times.

THere are also further protections if you happen to have bought the item with a credit card.

[ June 29, 2004, 10:02: Message edited by: dogscoff ]

[Baron Munchausen]

Well, Hellmart wasn't much help referring me to the manufacturer warranty... but the service company that handled the manufacturer warranty did a real zip-bang job. I left it with them (yes, had to drive there myself) and they called the next day saying it was repaired and ready for pickup. Wow... And now that I've got it back and setup it seems to work fine again. The repair form said they found an 'open transistor' and replaced it. I've never seen the word 'open' used in relation to a transistor before. Why not just 'burned out' or 'shorted'? Is this a 'technical' term?

The remaining question is, how long will it remain in good working order? The problem was apparently in the power supply and that makes me wonder if my habit of unplugging it every night to kill the annoying glow of the display panel might have had something to do with the problem. Heating up and cooling down every single day might be a good deal more stress than being plugged in all the time since being 'turned off' just reduces the amount of power in the unit and probably doesn't affect the heat level of the central power supply regulator much at all.

[ July 08, 2004, 22:54: Message edited by: Baron Munchausen ]

[Fyron]

Does the display panel have a "dim" feature?

[Parasite]

Originally posted by Baron Munchausen:
'open transistor' and replaced it. I've never seen the word 'open' used in relation to a transistor before. Why not just 'burned out' or 'shorted'? Is this a 'technical' term?

The remaining question is, how long will it remain in good working order? The problem was apparently in the power supply and that makes me wonder if my habit of unplugging it every night to kill the annoying glow of the display panel might have had something to do with the problem. Heating up and cooling down every single day might be a good deal more stress than being plugged in all the time since being 'turned off' just reduces the amount of power in the unit and probably doesn't affect the heat level of the central power supply regulator much at all.

"Open" is a kind of technical term. It means "broken apart" so no current will flow through it. 'burned out' will work. "Shorted" is the opposite problem. Current will always flow through it.

I don't think the turning it off at night could harm the new transistor. It was probobly a little bad to start with or not soldered in right. The sparking noises were it eating itself up till it went bad. If it had a habit of sparking or snapping when you turned it off though I would start to worry, but not if it happened randomly while turned on.

[Baron Munchausen]

It defaults to the dimmest mode when it's in 'standby' (off but plugged in) mode. It's still annoyingly bright in a dark room when you are trying to sleep. If I wanted a night-light I'd have bought one. Perhaps I'll devise a cover for it.