I picked up a used Micron AP150T at our town's recycling center. It cost
me nothing, so there is no loss if I can't figure out what's wrong.

When I hook it up to a computer, all works just fine. Then the picture
starts tearing horizontally after a few moments of on time. When I hit
the Function key, the function block pops up and looks perfectly fine
while the picture behind it is tearing.

So I assume that the sync signal from the computer is somehow being lost.
It does the same with two different computers, so the computer output is
not the problem; the computer outputs are fine with other monitors.

Any ideas? Is there a know problem with this unit syncing to the VGA
signal?

Al

On Sunday 04 May 2008 19:21, Al wrote:
I picked up a used Micron AP150T at our town's recycling center. It cost
me nothing, so there is no loss if I can't figure out what's wrong.

When I hook it up to a computer, all works just fine. Then the picture
starts tearing horizontally after a few moments of on time. When I hit
the Function key, the function block pops up and looks perfectly fine
while the picture behind it is tearing.

So I assume that the sync signal from the computer is somehow being lost.
It does the same with two different computers, so the computer output is
not the problem; the computer outputs are fine with other monitors.

Any ideas? Is there a know problem with this unit syncing to the VGA
signal?

Al

Does it always happen after the same time period? Also when you don't allow
time to cool down? Perhaps it's simply a connection somewhere which gets
interrupted when the monitor warms up.

Do you have a scope? If so, you could track the input sync signals in the
circuit, and find out where it gets mixed up. If all VGA signal enters the ADC
correctly, then the fault will be a bit more difficult to find...

On Sun, 04 May 2008 20:09:03 +0200, Wiebe Cazemier wrote:

On Sunday 04 May 2008 19:21, Al wrote:
I picked up a used Micron AP150T at our town's recycling center. It
cost me nothing, so there is no loss if I can't figure out what's
wrong.

snip


Does it always happen after the same time period? Also when you don't
allow time to cool down? Perhaps it's simply a connection somewhere
which gets interrupted when the monitor warms up.

Do you have a scope? If so, you could track the input sync signals in
the circuit, and find out where it gets mixed up. If all VGA signal
enters the ADC correctly, then the fault will be a bit more difficult to
find...

OK, I'll do the check with the 'scope. And the time of the start of the
tearing does vary with the interval between startups; something must be
temperature sensitive.

Al

On Sunday 04 May 2008 23:27, Al wrote:

OK, I'll do the check with the 'scope. And the time of the start of the
tearing does vary with the interval between startups; something must be
temperature sensitive.

That does not rule out capacitor based problems. I've repaired several
mainboards which had leaky capacitors, which worked fine as soon as they were
warm. It's the opposite to what you're experiencing, but it illustrates that
caps are temperature senstive.

On May 4, 3:42*pm, Wiebe Cazemier wrote:
On Sunday 04 May 2008 23:27, Al wrote:

OK, I'll do the check with the 'scope. And the time of the start of the
tearing does vary with the interval between startups; something must be
temperature sensitive.

That does not rule out capacitor based problems. I've repaired several
mainboards which had leaky capacitors, which worked fine as soon as they were
warm. It's the opposite to what you're experiencing, but it illustrates that
caps are temperature senstive.
If this is a crt monitor, there could be a high-voltage arc that is
not high enough to be seen or heard, but is generating "noise" that is
being picked up by some other circuit. A scope would be invaluable.

On Monday 05 May 2008 03:00, hr(bob) wrote:

If this is a crt monitor, there could be a high-voltage arc that is
not high enough to be seen or heard, but is generating "noise" that is
being picked up by some other circuit. A scope would be invaluable.

Judging by the subject, I would say it is not a CRT

"Wiebe Cazemier" wrote in message
b.home.nl...
On Sunday 04 May 2008 23:27, Al wrote:

OK, I'll do the check with the 'scope. And the time of the start of the
tearing does vary with the interval between startups; something must be
temperature sensitive.

That does not rule out capacitor based problems. I've repaired several
mainboards which had leaky capacitors, which worked fine as soon as they
were
warm. It's the opposite to what you're experiencing, but it illustrates
that
caps are temperature senstive.

Capacitors are very temperature sensitive, more so than any other part I can
think of, aside from those meant to react to temperature.

"Al" wrote in message
news:jgmTj.13391$qW.835@trnddc06...
I picked up a used Micron AP150T at our town's recycling center. It cost
me nothing, so there is no loss if I can't figure out what's wrong.

When I hook it up to a computer, all works just fine. Then the picture
starts tearing horizontally after a few moments of on time. When I hit
the Function key, the function block pops up and looks perfectly fine
while the picture behind it is tearing.

So I assume that the sync signal from the computer is somehow being lost.
It does the same with two different computers, so the computer output is
not the problem; the computer outputs are fine with other monitors.

Any ideas? Is there a know problem with this unit syncing to the VGA
signal?

Al

Bad electrolytic capacitors are fairly common and can cause any number of
strange symptoms. That's where I'd look first, the surface mount sort used
in flat panels tend to be especially troublesome.

On Sun, 04 May 2008 19:49:14 GMT, "James Sweet"
wrote:



"Al" wrote in message
news:jgmTj.13391$qW.835@trnddc06...
I picked up a used Micron AP150T at our town's recycling center. It cost
me nothing, so there is no loss if I can't figure out what's wrong.

When I hook it up to a computer, all works just fine. Then the picture
starts tearing horizontally after a few moments of on time. When I hit
the Function key, the function block pops up and looks perfectly fine
while the picture behind it is tearing.

So I assume that the sync signal from the computer is somehow being lost.
It does the same with two different computers, so the computer output is
not the problem; the computer outputs are fine with other monitors.

Any ideas? Is there a know problem with this unit syncing to the VGA
signal?

Al

Bad electrolytic capacitors are fairly common and can cause any number of
strange symptoms. That's where I'd look first, the surface mount sort used
in flat panels tend to be especially troublesome.


I second this. About 90% of the bad LCD monitors I see can be fixed
with new caps. Don't forget about the surface mount electrolytics on
the main board. I just fixed a Viewsonic that needed to have every
single cap on the main board replaced.
Andy Cuffe

On Mon, 05 May 2008 11:23:13 -0500, Andy Cuffe wrote:

On Sun, 04 May 2008 19:49:14 GMT, "James Sweet"
wrote:



"Al" wrote in message
news:jgmTj.13391$qW.835@trnddc06...
I picked up a used Micron AP150T at our town's recycling center. It
cost
me nothing, so there is no loss if I can't figure out what's wrong.

When I hook it up to a computer, all works just fine. Then the picture
starts tearing horizontally after a few moments of on time. When I hit
the Function key, the function block pops up and looks perfectly fine
while the picture behind it is tearing.

So I assume that the sync signal from the computer is somehow being
lost. It does the same with two different computers, so the computer
output is not the problem; the computer outputs are fine with other
monitors.

Any ideas? Is there a know problem with this unit syncing to the VGA
signal?

Al

Bad electrolytic capacitors are fairly common and can cause any number
of strange symptoms. That's where I'd look first, the surface mount sort
used in flat panels tend to be especially troublesome.


I second this. About 90% of the bad LCD monitors I see can be fixed
with new caps. Don't forget about the surface mount electrolytics on
the main board. I just fixed a Viewsonic that needed to have every
single cap on the main board replaced. Andy Cuffe



The display generated internally is just fine. Only the externally input
display tears. So it can't be "every single cap." I imagine it is
something in the sync input. I'll be checking it out. And like I said, it
is a "saved" monitor. If a quick fix won't do it, back to the dump.

Al

Al

The display generated internally is just fine. Only the externally input
display tears. So it can't be "every single cap." I imagine it is
something in the sync input. I'll be checking it out. And like I said, it
is a "saved" monitor. If a quick fix won't do it, back to the dump.

Al



Sure it could, may only be one or two that are bad enough to cause a
malfunction, but it's worth checking the rest. Usually when one of these
surface mount capacitors is bad, the rest are nearly shot too. I usually
replace them all, then the thing is good for years. In a pinch, one can
check the ESR of all of them and replace those that check bad. There's
usually only a dozen or so.

"James Sweet" wrote in message
news:w2ITj.5088$ch1.1375@trndny09...



The display generated internally is just fine. Only the externally input
display tears. So it can't be "every single cap." I imagine it is
something in the sync input. I'll be checking it out. And like I said, it
is a "saved" monitor. If a quick fix won't do it, back to the dump.

Al



Sure it could, may only be one or two that are bad enough to cause a
malfunction, but it's worth checking the rest. Usually when one of these
surface mount capacitors is bad, the rest are nearly shot too. I usually
replace them all, then the thing is good for years. In a pinch, one can
check the ESR of all of them and replace those that check bad. There's
usually only a dozen or so.


Agreed, but be aware that the ESR values of surface mount electros tends to
be somewhat higher than those of a similar value in 'conventional' leaded
format, so a cap that you are expecting to read say 1 ohm, may correctly
read several ohms in surface mount.

Arfa

James Sweet wrote:

Usually when one of these
surface mount capacitors is bad, the rest are nearly shot too. I usually
replace them all, then the thing is good for years.

I'd be interested to know what makes you so sure that the caps
you bought for replacement are of superior longevity compared
to those the manufacturer did put in :-).

Regards,
H.

On Mon, 05 May 2008 17:57:38 GMT, Al wrote:


The display generated internally is just fine. Only the externally input
display tears. So it can't be "every single cap." I imagine it is
something in the sync input. I'll be checking it out. And like I said, it
is a "saved" monitor. If a quick fix won't do it, back to the dump.

Al

Al

It's not unusual for bad caps to only affect the video from the
computer, leaving the OSD looking fine.
Andy Cuffe