Monitor Hissing At Me!

T

Tim H.

Guest
Hello,

My dad's monitor decided to call it quits on him w/out any warning. It's a
no-name monitor with a Samsung tube and a ProView microcontroller. He did
say he heard a paper-rustling type sound before it went. I can only imagine
it was the flyback doing that. I go to turn it on and I just hear the power
supply cycling and the green LED on the front is flickering. I do a little
digging, check for obvious shorts (HOT, caps, etc) and discover that the HOT
is shorted. I yank out of the circuit and test it off-board -- she's dead.
Just for kicks, I measure Vec of the HOT while it was out of circuit and I
measured 62V.

Just for the heck of it, I did a little part matching and put in another
HOT, fired it up. I got the normal relay clicking sounds, heard the HV and
then it went to hissing, corona hiss? Almost like it's arcing inside the
flyback. Few seconds later, the HOT goes again as the power supply went back
to cycling.

Unplug the monitor, wait a few minutes. Check the filter caps, make sure
they're discharged -- all good. I look over the board for cold solder joints
or burn spots and I come across a relay with 6 of the 8 pins where the
solder looks like it vanished. I resolder it, put another HOT in and fire it
up. I get the normal sounds and it returns to hissing. I power it off and
there was a "poof" kind of sound and dust shot out from between the flyback
and the top of the PCB. It didn't smell so well either.

I'm certainly not trained to work on monitors/TVs, but I keep my hands away
from what I know is dangerous =) At this point, given the sound of the
flyback, I would almost say it's shorted inside. Below is a link of me
powering it up with the mic about 5" away. I then move the mic towards the
solder side of the flyback. The first "click" you hear is the power switch,
the rest are relays.

http://tekphobia.home.comcast.net/monitorhiss.wav (854KB WAV)

http://tekphobia.home.comcast.net/monitorhiss.mp3 (311KB MP3)

Thanks,

Tim
 
"Tim H." <tekphobia@comcast.net> wrote in message
news:n1APb.96475$Rc4.580727@attbi_s54...
Hello,

My dad's monitor decided to call it quits on him w/out any warning. It's a
no-name monitor with a Samsung tube and a ProView microcontroller. He did
say he heard a paper-rustling type sound before it went. I can only
imagine
it was the flyback doing that. I go to turn it on and I just hear the
power
supply cycling and the green LED on the front is flickering. I do a little
digging, check for obvious shorts (HOT, caps, etc) and discover that the
HOT
is shorted. I yank out of the circuit and test it off-board -- she's dead.
Just for kicks, I measure Vec of the HOT while it was out of circuit and I
measured 62V.

Just for the heck of it, I did a little part matching and put in another
HOT, fired it up. I got the normal relay clicking sounds, heard the HV and
then it went to hissing, corona hiss? Almost like it's arcing inside the
flyback. Few seconds later, the HOT goes again as the power supply went
back
to cycling.

Unplug the monitor, wait a few minutes. Check the filter caps, make sure
they're discharged -- all good. I look over the board for cold solder
joints
or burn spots and I come across a relay with 6 of the 8 pins where the
solder looks like it vanished. I resolder it, put another HOT in and fire
it
up. I get the normal sounds and it returns to hissing. I power it off and
there was a "poof" kind of sound and dust shot out from between the
flyback
and the top of the PCB. It didn't smell so well either.

I'm certainly not trained to work on monitors/TVs, but I keep my hands
away
from what I know is dangerous =) At this point, given the sound of the
flyback, I would almost say it's shorted inside. Below is a link of me
powering it up with the mic about 5" away. I then move the mic towards the
solder side of the flyback. The first "click" you hear is the power
switch,
the rest are relays.

http://tekphobia.home.comcast.net/monitorhiss.wav (854KB WAV)

http://tekphobia.home.comcast.net/monitorhiss.mp3 (311KB MP3)

Thanks,

Tim
Click to expand...

I would suspect the flyback, you might be able to tell if you power it up in
a dark room and look, try putting a lightbulb in series with the B+ line.
 
same problem with a duel HOT viewsonic.

If your familiar with a P775

Its probably a combination of both the flyback and driver transformer.




"James Sweet" <jamessweet@hotmail.com> wrote in message
news:XQAPb.118630$na.113375@attbi_s04...
"Tim H." <tekphobia@comcast.net> wrote in message
news:n1APb.96475$Rc4.580727@attbi_s54...
Hello,

My dad's monitor decided to call it quits on him w/out any warning. It's
a
no-name monitor with a Samsung tube and a ProView microcontroller. He
did
say he heard a paper-rustling type sound before it went. I can only
imagine
it was the flyback doing that. I go to turn it on and I just hear the
power
supply cycling and the green LED on the front is flickering. I do a
little
digging, check for obvious shorts (HOT, caps, etc) and discover that the
HOT
is shorted. I yank out of the circuit and test it off-board -- she's
dead.
Just for kicks, I measure Vec of the HOT while it was out of circuit and
I
measured 62V.

Just for the heck of it, I did a little part matching and put in another
HOT, fired it up. I got the normal relay clicking sounds, heard the HV
and
then it went to hissing, corona hiss? Almost like it's arcing inside the
flyback. Few seconds later, the HOT goes again as the power supply went
back
to cycling.

Unplug the monitor, wait a few minutes. Check the filter caps, make sure
they're discharged -- all good. I look over the board for cold solder
joints
or burn spots and I come across a relay with 6 of the 8 pins where the
solder looks like it vanished. I resolder it, put another HOT in and
fire
it
up. I get the normal sounds and it returns to hissing. I power it off
and
there was a "poof" kind of sound and dust shot out from between the
flyback
and the top of the PCB. It didn't smell so well either.

I'm certainly not trained to work on monitors/TVs, but I keep my hands
away
from what I know is dangerous =) At this point, given the sound of the
flyback, I would almost say it's shorted inside. Below is a link of me
powering it up with the mic about 5" away. I then move the mic towards
the
solder side of the flyback. The first "click" you hear is the power
switch,
the rest are relays.

http://tekphobia.home.comcast.net/monitorhiss.wav (854KB WAV)

http://tekphobia.home.comcast.net/monitorhiss.mp3 (311KB MP3)

Thanks,

Tim




I would suspect the flyback, you might be able to tell if you power it up
in
a dark room and look, try putting a lightbulb in series with the B+ line.
Click to expand...
 
If you can find the parts, replace the flyback, driver transformer, change
the HOT again (re-damaged), verify the power supply specs, and do an ESR
test on all the capacitors in the power supply, and scan circuits. Replace
any caps that are high in ESR.

I think you will find it a more feasible project to replace the monitor.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Tim H." <tekphobia@comcast.net> wrote in message
news:n1APb.96475$Rc4.580727@attbi_s54...
Hello,

My dad's monitor decided to call it quits on him w/out any warning. It's a
no-name monitor with a Samsung tube and a ProView microcontroller. He did
say he heard a paper-rustling type sound before it went. I can only imagine
it was the flyback doing that. I go to turn it on and I just hear the power
supply cycling and the green LED on the front is flickering. I do a little
digging, check for obvious shorts (HOT, caps, etc) and discover that the HOT
is shorted. I yank out of the circuit and test it off-board -- she's dead.
Just for kicks, I measure Vec of the HOT while it was out of circuit and I
measured 62V.

Just for the heck of it, I did a little part matching and put in another
HOT, fired it up. I got the normal relay clicking sounds, heard the HV and
then it went to hissing, corona hiss? Almost like it's arcing inside the
flyback. Few seconds later, the HOT goes again as the power supply went back
to cycling.

Unplug the monitor, wait a few minutes. Check the filter caps, make sure
they're discharged -- all good. I look over the board for cold solder joints
or burn spots and I come across a relay with 6 of the 8 pins where the
solder looks like it vanished. I resolder it, put another HOT in and fire it
up. I get the normal sounds and it returns to hissing. I power it off and
there was a "poof" kind of sound and dust shot out from between the flyback
and the top of the PCB. It didn't smell so well either.

I'm certainly not trained to work on monitors/TVs, but I keep my hands away
from what I know is dangerous =) At this point, given the sound of the
flyback, I would almost say it's shorted inside. Below is a link of me
powering it up with the mic about 5" away. I then move the mic towards the
solder side of the flyback. The first "click" you hear is the power switch,
the rest are relays.

http://tekphobia.home.comcast.net/monitorhiss.wav (854KB WAV)

http://tekphobia.home.comcast.net/monitorhiss.mp3 (311KB MP3)

Thanks,

Tim
 
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