TV sounds like dripping faucet when off

[Paul E. Schoen]

This might not be directly related to design, although possibly the
original design of the TV, so here goes..

I have a fairly old (maybe 1990) Emerson color TV which has worked fine for
all that time. A few days ago, I heard a sound that was just like a
dripping faucet, at about a one second repetition rate. I traced it to the
TV, and it seemed to be coming from the speaker. I unplugged it, because I
have heard of some TVs catching fire when their standby circuits
malfunctioned. It seemed OK later when I reapplied power, but the problem
returned some time after I turned it off.

The TV may have been damaged by the close lightning strike that I described
in early July. I also noticed soon after that happened, that there is a
streak in the center of the screen that shows an abnormally red color.

It's probably not worth taking apart and doing extensive troubleshooting,
but I just wanted to know if anyone has experienced anything like this, and
what it might be. It acts like a buildup of charge and then a sudden
discharge, but I would think the only thing powered up when it is off is
the remote control IR detector circuit. The power on circuit might trigger
a triac that could be leaky, but I hear a distinct click when the TV turns
on, indicating a relay.

I need to move the TV soon to do some remodeling. Maybe I'll take it apart
and see if there's anything obvious. Otherwise, maybe it would be safer to
just get a new TV for $200 or so. Meanwhile, I'll keep it unplugged while
not watching it.

Paul

 

[Jim Thompson]

This might not be directly related to design, although possibly the
original design of the TV, so here goes..

I have a fairly old (maybe 1990) Emerson color TV which has worked fine for
all that time. A few days ago, I heard a sound that was just like a
dripping faucet, at about a one second repetition rate. I traced it to the
TV, and it seemed to be coming from the speaker. I unplugged it, because I
have heard of some TVs catching fire when their standby circuits
malfunctioned. It seemed OK later when I reapplied power, but the problem
returned some time after I turned it off.

The TV may have been damaged by the close lightning strike that I described
in early July. I also noticed soon after that happened, that there is a
streak in the center of the screen that shows an abnormally red color.

It's probably not worth taking apart and doing extensive troubleshooting,
but I just wanted to know if anyone has experienced anything like this, and
what it might be. It acts like a buildup of charge and then a sudden
discharge, but I would think the only thing powered up when it is off is
the remote control IR detector circuit. The power on circuit might trigger
a triac that could be leaky, but I hear a distinct click when the TV turns
on, indicating a relay.

I need to move the TV soon to do some remodeling. Maybe I'll take it apart
and see if there's anything obvious. Otherwise, maybe it would be safer to
just get a new TV for $200 or so. Meanwhile, I'll keep it unplugged while
not watching it.

Paul

(1) Take the back off and thoroughly vacuum the dust out of it (while
unplugged of course ;-)

(2) Power it up, then degauss the screen.

...Jim Thompson

 

[Don Lancaster]

This might not be directly related to design, although possibly the
original design of the TV, so here goes..

I have a fairly old (maybe 1990) Emerson color TV which has worked fine for
all that time. A few days ago, I heard a sound that was just like a
dripping faucet, at about a one second repetition rate. I traced it to the
TV, and it seemed to be coming from the speaker. I unplugged it, because I
have heard of some TVs catching fire when their standby circuits
malfunctioned. It seemed OK later when I reapplied power, but the problem
returned some time after I turned it off.

The TV may have been damaged by the close lightning strike that I described
in early July. I also noticed soon after that happened, that there is a
streak in the center of the screen that shows an abnormally red color.

It's probably not worth taking apart and doing extensive troubleshooting,
but I just wanted to know if anyone has experienced anything like this, and
what it might be. It acts like a buildup of charge and then a sudden
discharge, but I would think the only thing powered up when it is off is
the remote control IR detector circuit. The power on circuit might trigger
a triac that could be leaky, but I hear a distinct click when the TV turns
on, indicating a relay.

I need to move the TV soon to do some remodeling. Maybe I'll take it apart
and see if there's anything obvious. Otherwise, maybe it would be safer to
just get a new TV for $200 or so. Meanwhile, I'll keep it unplugged while
not watching it.

Paul

Obviously a drain problem on a field effect transistor.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[Jim Thompson]

Obviously a drain problem on a field effect transistor.

Sno-o-o-o-ort ;-)

...Jim Thompson

 

[Paul Hovnanian P.E.]

This might not be directly related to design, although possibly the
original design of the TV, so here goes..

I have a fairly old (maybe 1990) Emerson color TV which has worked fine for
all that time. A few days ago, I heard a sound that was just like a
dripping faucet, at about a one second repetition rate. I traced it to the
TV, and it seemed to be coming from the speaker. I unplugged it, because I
have heard of some TVs catching fire when their standby circuits
malfunctioned. It seemed OK later when I reapplied power, but the problem
returned some time after I turned it off.

The TV may have been damaged by the close lightning strike that I described
in early July. I also noticed soon after that happened, that there is a
streak in the center of the screen that shows an abnormally red color.

It's probably not worth taking apart and doing extensive troubleshooting,
but I just wanted to know if anyone has experienced anything like this, and
what it might be. It acts like a buildup of charge and then a sudden
discharge, but I would think the only thing powered up when it is off is
the remote control IR detector circuit.

On a Magnavox set I recently dug into, the primary switching power
supply is always hot. There is 130 Vdc to the HV flyback primary.
Turning the set 'on' enables its switching circuitry and the tuner and
audio systems. The only relay in that set powers the degaussing coil.

The power on circuit might trigger a triac that could be leaky, but I hear a distinct click
when the TV turns on, indicating a relay.

It could be a primary power relay, or the degaussing supply. But there
is enough stuff energized in a set that is off to cause a bad component
or dirty trace to flash over periodically.

I need to move the TV soon to do some remodeling. Maybe I'll take it apart
and see if there's anything obvious. Otherwise, maybe it would be safer to
just get a new TV for $200 or so. Meanwhile, I'll keep it unplugged while
not watching it.

Not a bad idea. In my experience, when the bad component finally goes
bang, if you are there to unplug it and prevent further damage, it makes
the diagnostic process a lot simpler. Just look for burnt stuff.

 

[Michael A. Terrell]

This might not be directly related to design, although possibly the
original design of the TV, so here goes..

I have a fairly old (maybe 1990) Emerson color TV which has worked fine for
all that time. A few days ago, I heard a sound that was just like a
dripping faucet, at about a one second repetition rate. I traced it to the
TV, and it seemed to be coming from the speaker. I unplugged it, because I
have heard of some TVs catching fire when their standby circuits
malfunctioned. It seemed OK later when I reapplied power, but the problem
returned some time after I turned it off.

The TV may have been damaged by the close lightning strike that I described
in early July. I also noticed soon after that happened, that there is a
streak in the center of the screen that shows an abnormally red color.

It's probably not worth taking apart and doing extensive troubleshooting,
but I just wanted to know if anyone has experienced anything like this, and
what it might be. It acts like a buildup of charge and then a sudden
discharge, but I would think the only thing powered up when it is off is
the remote control IR detector circuit. The power on circuit might trigger
a triac that could be leaky, but I hear a distinct click when the TV turns
on, indicating a relay.

I need to move the TV soon to do some remodeling. Maybe I'll take it apart
and see if there's anything obvious. Otherwise, maybe it would be safer to
just get a new TV for $200 or so. Meanwhile, I'll keep it unplugged while
not watching it.

Paul

Try . Give them the Brand and Model
numbers, as well as the symptoms and they may be able to help you.

It sounds like some failing electrolytics in the switching power
supply.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Paul E. Schoen]

Sno-o-o-o-ort ;-)

If this were a much older model, especially one made in the UK, I would
suspect a leaky valve!

(Thanks for the suggestions, BTW)

Paul

 

[Frithiof Andreas Jensen]

This might not be directly related to design, although possibly the
original design of the TV, so here goes..

I have a fairly old (maybe 1990) Emerson color TV which has worked fine for
all that time. A few days ago, I heard a sound that was just like a
dripping faucet, at about a one second repetition rate. I traced it to the
TV, and it seemed to be coming from the speaker.

Could be the power supply electrolytics running dry (literally, the electrolytic
cooks away slowly over time):

In standby the power supply deliberately runs in a burst mode swithing On for a
few msec every few seconds- mainly because the regulator in the 150W(???) does
not control that low (5W ???) but it *does* conserve some power. If the output
capacitors are weak, the supply voltage will vary quite a bit which might feed
over to the audio circuits. In normal use the power supply performs glossing
over the problem.

I unplugged it, because I
have heard of some TVs catching fire when their standby circuits
malfunctioned.

Sensible - TV's *like* to catch fire; like tumble-driers.

I need to move the TV soon to do some remodeling. Maybe I'll take it apart
and see if there's anything obvious. Otherwise, maybe it would be safer to
just get a new TV for $200 or so. Meanwhile, I'll keep it unplugged while
not watching it.

If you are really devious, you remodel *after* the TV catches fire ....

 

[xray]

Obviously a drain problem on a field effect transistor.

Could be a leaking tap on a transformer or coil. I would think a drain
problem would cause increasing gurgling/sloshing sounds or puddles of
electrons near the device.

 

[Rich Grise]

This might not be directly related to design, although possibly the
original design of the TV, so here goes..

I have a fairly old (maybe 1990) Emerson color TV which has worked fine
for all that time. A few days ago, I heard a sound that was just like a
dripping faucet, at about a one second repetition rate. I traced it to the
TV, and it seemed to be coming from the speaker. I unplugged it, because I
have heard of some TVs catching fire when their standby circuits
malfunctioned. It seemed OK later when I reapplied power, but the problem
returned some time after I turned it off.

The TV may have been damaged by the close lightning strike that I
described in early July. I also noticed soon after that happened, that
there is a streak in the center of the screen that shows an abnormally red
color.

It was the lightning. You can fix it, if you're good with TVs. I once was
sitting in my apartment, watching TV, and the building took a direct
strike. It killed the answering machine, so luckily the modem was
unplugged, and the TV acted normal, until I went to turn it off and it
wouldn't turn off. Turned out it was the "turn it on or off by the remote"
transistor, like a 2N3904, had gone short. Cost me $30.00 to get it
diagnosed, and a spare transistor and a few minutes to fix it.

Lightning does strange things, and it sounds like your circuit has been
mysteriously altered, such that you have a relaxation oscillator somewhere
in there.

Like I said, you can fix it, if you have the schematic and all the voltage
and signal specs, a scope or so, and etc., but you have to be OK with
fixing TVs.

Good Luck!
Rich