Monitor horizonal "jiggle band" problem... Any advice most welcome!

  • Thread starter Thread starter Chris J...
  • Start date Start date
C

Chris J...

I've got a Sylvania F96 19 inch CRT, about three (perhaps four) yours
old. It's been a good monitor so far, and I work from home via
computer so it gets a great deal of use.

Recently though, it's developed a weird "jiggle" in the screen. The
best way I can describe it is that a band of horizonal displacement
slowly moves down the screen, taking about 30 seconds to do so. Upon
reaching the bottom, it re-appears at the top. It only displaces by a
few pixels, but it's annoying when reading small text. More
importantly, it seems to be getting worse.

It only seems to occur at high screen res, 1280X1024 32 bit, 60hz
(lowest Hz I can select).
I've tried it at a lower res and haven't seen the problem.
Unfortunately, I need the high res so just decreasing the screen size
isn't a long-term fix.

My first thought was interference, so I turned off the main breaker
for the house and ran it from the UPS, and it was no different.

Second thought; other hardware. I've recently re-built the system (the
problem was occurring before the rebuild) so I don't think it's
hardware. To confirm, I borrowed a friend's identical monitor, and the
problem did not occur. However, hooking my monitor to his computer and
running at the same res and HZ did cause the problem to occur.

In case it makes any difference, the present system is an AMD 3400 on
a Asus A8V deluxe MB, 2 gigs of RAM, and an Nvidia 64 meg card.

Anyone have any idea what this problem might be? And if I'm right in
guessing it will get worse? I have few skills troubleshooting and
fixing electronics, though I can use a multimeter and can solder
boards, so I'm willing to give it a try if needed, but I'd prefer not
to spend a lot on this old a monitor.

Thanks for any thoughts or advice.
Chris
 
If you've tried different resolutions, and refresh rates, your monitor may
be comming to its lifes end. You did mention you work from home, and it
gets lots of use so thats most likly what it is. Buy a new one! A new
monitor always clears the mind!
 
If you've tried different resolutions, and refresh rates, your monitor may
be comming to its lifes end. You did mention you work from home, and it
gets lots of use so thats most likly what it is. Buy a new one! A new
monitor always clears the mind!
Click to expand...

I tried different resolutions, and that's the odd thing; at lower
resolutions (such as 1024X768 32 bit) the problem does not occur.

Unfortunately I really need the higher res, so running at a lower res
won't work.

I'd guess the monitor is on 40+ hours a week on average, so that does
add up over the years.

One reason I am trying to avoid buying a new one is that it's a 300
mile round trip to the nearest store with anything but smaller CRT's,
(I don't want an LCD) and I won't buy one without seeing it run. But,
if I can't fix it, I don't have a choice.

Thanks!
 
These types of faults are usually attributed to decoupler caps in the
flyback and power supply circuits. An experienced tech who works on monitors
can do ESR testing on the caps, and find the defective ones. The labour will
be the expensive part. The caps are not very expensive.

Considering the age of the monitor, I would not put money in to it. The new
generation of LCD screens are very impressive to work with.

--

Jerry G.
======



I've got a Sylvania F96 19 inch CRT, about three (perhaps four) yours
old. It's been a good monitor so far, and I work from home via
computer so it gets a great deal of use.

Recently though, it's developed a weird "jiggle" in the screen. The
best way I can describe it is that a band of horizonal displacement
slowly moves down the screen, taking about 30 seconds to do so. Upon
reaching the bottom, it re-appears at the top. It only displaces by a
few pixels, but it's annoying when reading small text. More
importantly, it seems to be getting worse.

It only seems to occur at high screen res, 1280X1024 32 bit, 60hz
(lowest Hz I can select).
I've tried it at a lower res and haven't seen the problem.
Unfortunately, I need the high res so just decreasing the screen size
isn't a long-term fix.

My first thought was interference, so I turned off the main breaker
for the house and ran it from the UPS, and it was no different.

Second thought; other hardware. I've recently re-built the system (the
problem was occurring before the rebuild) so I don't think it's
hardware. To confirm, I borrowed a friend's identical monitor, and the
problem did not occur. However, hooking my monitor to his computer and
running at the same res and HZ did cause the problem to occur.

In case it makes any difference, the present system is an AMD 3400 on
a Asus A8V deluxe MB, 2 gigs of RAM, and an Nvidia 64 meg card.

Anyone have any idea what this problem might be? And if I'm right in
guessing it will get worse? I have few skills troubleshooting and
fixing electronics, though I can use a multimeter and can solder
boards, so I'm willing to give it a try if needed, but I'd prefer not
to spend a lot on this old a monitor.

Thanks for any thoughts or advice.
Chris
 
These types of faults are usually attributed to decoupler caps in the
flyback and power supply circuits. An experienced tech who works on monitors
can do ESR testing on the caps, and find the defective ones. The labour will
be the expensive part. The caps are not very expensive.
Click to expand...
Considering the age of the monitor, I would not put money in to it. The new
generation of LCD screens are very impressive to work with.
Click to expand...

One problem I have is that the nearest repair place is in Phoenix, the
nearest large city to me, a 300 mile round trip. I'd have to haul the
monitor down there, drop it off, then go pick it up if they fix it,
for a grand total of 600 miles of driving. So, because of that and the
age, I'm disinclined to take it in to be fixed. I'd also like to get a
bigger monitor this time, maybe 24".

I've downloaded all the posts on this NG that my server has, 53,000 of
them, and I'm searching posts with LCD in the title, and am up to late
2003 so far. My concern here is that I've seen plenty of opinions that
the LCD screens don't seem to have the clarity and sharpness of the
CRT's at high res. Maybe that will change as I read the more recent
posts, but I'm wary so far.

Thanks!!!
 
Chris J... said:
I've got a Sylvania F96 19 inch CRT, about three (perhaps four)
yours old. It's been a good monitor so far, and I work from home
via computer so it gets a great deal of use.

Recently though, it's developed a weird "jiggle" in the screen.
The best way I can describe it is that a band of horizonal
displacement slowly moves down the screen, taking about 30
seconds to do so. Upon reaching the bottom, it re-appears at the
top. It only displaces by a few pixels, but it's annoying when
reading small text. More importantly, it seems to be getting worse.
.... snip ...

Anyone have any idea what this problem might be? And if I'm right
in guessing it will get worse? I have few skills troubleshooting
and fixing electronics, though I can use a multimeter and can
solder boards, so I'm willing to give it a try if needed, but I'd
prefer not to spend a lot on this old a monitor.
Click to expand...

I expect it is some sort of beat frequence effect between the mains
and your refresh rate, indicating some sort of problem with the low
voltage supplies, such as failing capacitors. There are two
possible explanations of the change with resolution: the rep. rate
changes, and the low frequency beat goes away; or the load on the
supply changes, so the filtering works adequately.

The bad capacitor theory also agrees with the 'getting worse'
symptom. I assume you know about lethal high voltages within the
monitor even long after it has been turned off.

It likely needs a 50 cent part. The question is which one. :-)
 
Chris said:
One problem I have is that the nearest repair place is in Phoenix, the
nearest large city to me, a 300 mile round trip. I'd have to haul the
monitor down there, drop it off, then go pick it up if they fix it,
for a grand total of 600 miles of driving. So, because of that and the
age, I'm disinclined to take it in to be fixed. I'd also like to get a
bigger monitor this time, maybe 24".

I've downloaded all the posts on this NG that my server has, 53,000 of
them, and I'm searching posts with LCD in the title, and am up to late
2003 so far. My concern here is that I've seen plenty of opinions that
the LCD screens don't seem to have the clarity and sharpness of the
CRT's at high res. Maybe that will change as I read the more recent
posts, but I'm wary so far.

Thanks!!
Click to expand...

I grew up in Page in the 1960's. I feel your pain!

Q
 
Chris J... said:
I've got a Sylvania F96 19 inch CRT, about three (perhaps four) yours
old. It's been a good monitor so far, and I work from home via
computer so it gets a great deal of use.

Recently though, it's developed a weird "jiggle" in the screen. The
best way I can describe it is that a band of horizonal displacement
slowly moves down the screen, taking about 30 seconds to do so. Upon
reaching the bottom, it re-appears at the top. It only displaces by a
few pixels, but it's annoying when reading small text. More
importantly, it seems to be getting worse.
Click to expand...
---- said:
Anyone have any idea what this problem might be? And if I'm right in
guessing it will get worse? I have few skills troubleshooting and
fixing electronics, though I can use a multimeter and can solder
boards, so I'm willing to give it a try if needed, but I'd prefer not
to spend a lot on this old a monitor.
Click to expand...
My prime suspect would be the first filter capacitor in the
power supply section. It's probably one of the largest caps
with a value of some hundreds of microfarads and rated for
about 400V if the monitor is a universal type, and about
200V if it's rated only for 110-120V mains.

It should cost no more than a couple of $ and in view of
the problems posed by your location, it wouldn't hurt to try
replacing that capacitor. Before touching any part of the
circuit, measure the voltage across that and other caps to
make sure they're not still charged with potentially
dangerous voltages.
 
I expect it is some sort of beat frequence effect between the mains
and your refresh rate, indicating some sort of problem with the low
voltage supplies, such as failing capacitors. There are two
possible explanations of the change with resolution: the rep. rate
changes, and the low frequency beat goes away; or the load on the
supply changes, so the filtering works adequately.
Click to expand...
The bad capacitor theory also agrees with the 'getting worse'
symptom. I assume you know about lethal high voltages within the
monitor even long after it has been turned off.
Click to expand...

I do indeed. When I was in college a friend of mine, after a few
drinks (very bad idea!) try and fix a TV set. He unplugged it, and was
arguing with me about capacitor charges (I was telling him it was
still dangerous although unplugged, he felt otherwise) when he got a
hefty shock and jumped back a few feet. He was stunned but ok, and
I've decided that I'd prefer not to experience it firsthand. :-)

I usually wait 24 hours after unplugging before going inside a CRT or
TV case, and even then I check with a multimeter before touching
things.
It likely needs a 50 cent part. The question is which one. :-)
Click to expand...

ROFL!
Well, I'm thinking I need detailed wiring diagrams and specs for this,
and I'm also thinking that It's well worth giving it a try. All I have
to lose is a few $$ for parts, and the possibility of killing the
monitor (that will probably soon be dead anyway).
 
My prime suspect would be the first filter capacitor in the
power supply section. It's probably one of the largest caps
with a value of some hundreds of microfarads and rated for
about 400V if the monitor is a universal type, and about
200V if it's rated only for 110-120V mains.
Click to expand...

I think it's only 110-120, as there is no switch for 220.
It should cost no more than a couple of $ and in view of
the problems posed by your location, it wouldn't hurt to try
replacing that capacitor. Before touching any part of the
circuit, measure the voltage across that and other caps to
make sure they're not still charged with potentially
dangerous voltages.
Click to expand...

Will do, and thanks... I'll leave the monitor unplugged for 24 hours
first, but always check for voltages anyway.

I can test some of the specs with a digital multimeter, but that won't
help for actual full-power operating levels. I don't have an
oscilloscope or any other test gear.

Or is there a way to test the capacitor sufficiently, or should I just
try and find one online and replace it? I can solder, so
actually removing and replacing it shouldn't be too hard.

As cheap as capacitors are, I'm seriously thinking of finding the one
you mentioned, plus a few others in the low voltage supplies. I
haven't had the case off yet to look, but if there are only a few,
then the easiest way might be to replace all the suspect ones?

Thanks!!!
 
I grew up in Page in the 1960's. I feel your pain!
Click to expand...

Wow, that would be far, far worse than my situation! I've been to
page, a few months ago, and it is several hour's drive from
Flagstaff. In the 60's it must have been a much slower road, and
Flagstaff was tiny. Heck, Phoenix wasn't too much back then, from what
I have heard.
 
Chris J... said:
I think it's only 110-120, as there is no switch for 220.


Will do, and thanks... I'll leave the monitor unplugged for 24 hours
first, but always check for voltages anyway.

I can test some of the specs with a digital multimeter, but that won't
help for actual full-power operating levels. I don't have an
oscilloscope or any other test gear.

Or is there a way to test the capacitor sufficiently, or should I just
try and find one online and replace it? I can solder, so
actually removing and replacing it shouldn't be too hard.
Click to expand...
Dedicated instruments and some multimeters can test caps
for capacitance, ESR, leakage, etc. But in your case, it may
be simpler to just replace it and see if it makes a difference.
It's also possible to make a fair guess about the condition
of a capacitor with a needle-type analog multimeter, but it
requires some experience.

Another approach would be to monitor the ripple voltage
across the cap(s) with an oscilloscope while it's turned on.
But that's really a job for an experienced tech.

The absence of a voltage selector switch does not necessarily
mean that it's a single-standard product. Modern switched-
mode power supplies are often designed to automatically
make stepless adjustment over a wide range of mains voltages,
e.g. 80-260 Volts.

Even if your monitor is a universal type, it may use two 200V
or 250V caps in series instead of a single 400V unit.

BTW, those filter capacitors are generally not critical in value.
If the original cap is, say, a 330uF unit, replacing it with 220
or 470uF will make little difference and won't do any harm if
those values are easier to get.
As cheap as capacitors are, I'm seriously thinking of finding the one
you mentioned, plus a few others in the low voltage supplies. I
haven't had the case off yet to look, but if there are only a few,
then the easiest way might be to replace all the suspect ones?
Click to expand...
Upto you. Personally I'm one of those people who like to
know exactly where the problem lies, and I'd start by replacing
only the master DC filter cap.
 
Chris said:
I tried different resolutions, and that's the odd thing; at lower
resolutions (such as 1024X768 32 bit) the problem does not occur.
Click to expand...

In addition to Zotin Khuma's excellent advice, first try removing all
sources of magnetic interference, such as speakers, cooling fans (for
keeping humans cool, not computers), and fluorescent lamps. Also try a
different video card, video card BIOS (can be loaded into memory,
without reflashing the card), or video driver because its refresh rates
may differ just enough to to eliminate the interference. Some video
cards will cause jiggle (breathing) if their BIOS or driver times the
video RAM too aggressively.
 
In addition to Zotin Khuma's excellent advice, first try removing all
sources of magnetic interference, such as speakers, cooling fans (for
keeping humans cool, not computers), and fluorescent lamps.
Click to expand...

I do have fluorescent lamps in the room, but tried unplugging them, no
difference.
Also try a
different video card, video card BIOS (can be loaded into memory,
without reflashing the card), or video driver because its refresh rates
may differ just enough to to eliminate the interference. Some video
cards will cause jiggle (breathing) if their BIOS or driver times the
video RAM too aggressively.
Click to expand...

I tried it on another computer instead, with much different hardware,
and got the same problem.
 
Dedicated instruments and some multimeters
Click to expand...

I have a digital multimeter, but it's not exactly high quality; it
cost me $10, new. It will (theoretically) test for capacitance, but
not leakage.
can test caps
for capacitance, ESR, leakage, etc. But in your case, it may
be simpler to just replace it and see if it makes a difference.
It's also possible to make a fair guess about the condition
of a capacitor with a needle-type analog multimeter, but it
requires some experience.
Click to expand...
Another approach would be to monitor the ripple voltage
across the cap(s) with an oscilloscope while it's turned on.
But that's really a job for an experienced tech.
Click to expand...

I'm lacking in both the tools and the experience, so I think I'd
better go with replacement...
The absence of a voltage selector switch does not necessarily
mean that it's a single-standard product. Modern switched-
mode power supplies are often designed to automatically
make stepless adjustment over a wide range of mains voltages,
e.g. 80-260 Volts.
Click to expand...

Ahhh! Thanks, i didn't know that.
Even if your monitor is a universal type, it may use two 200V
or 250V caps in series instead of a single 400V unit.
Click to expand...
BTW, those filter capacitors are generally not critical in value.
If the original cap is, say, a 330uF unit, replacing it with 220
or 470uF will make little difference and won't do any harm if
those values are easier to get.
Click to expand...

Ahhh! You just saved me a load of trouble, thank you! I was going to
try and find exact matches for them.

BTW, any suggestions for a good source for these sort of things
online?
Upto you. Personally I'm one of those people who like to
know exactly where the problem lies, and I'd start by replacing
only the master DC filter cap.
Click to expand...

Hmmm. I would like to know where the problem is, but I don't want to
have to order one capacitor, wait for delivery, then do it all again.
I think I'll order all the capacitors, then just replace the DC filter
one, and see what happens. That way, if I need to replace more, I have
them here to do it without the waiting and expense of fed-ex.

Thanks!
 
Ahhh! You just saved me a load of trouble, thank you! I was going to
try and find exact matches for them.
Click to expand...

Though the values aren't critical, you might consider that
the caps already in the circuit, "may" be the failure point
and ideally would be upgraded. Also, you need consider the
diameter of the part, what will fit on the PCB and the lead
spacing.

BTW, any suggestions for a good source for these sort of things
online?
Click to expand...

The prices here are attractive, though I don't know how old
they are,
http://www.goldmine-elec-products.com/products.asp?dept=1222
and also it goes back to what I wrote above about acceptible
dimensions on the part. I'm not even so sure it's those
caps that are the problem though, seems more like some
failure in the vertical circuit to me (but I am not a
monitor repairman).

Hmmm. I would like to know where the problem is, but I don't want to
have to order one capacitor, wait for delivery, then do it all again.
I think I'll order all the capacitors, then just replace the DC filter
one, and see what happens. That way, if I need to replace more, I have
them here to do it without the waiting and expense of fed-ex.

Thanks!
Click to expand...

That can get pretty expensive unless you foresee some need
for the unused caps in the future. A 4 year old monitor is
about that age where it's unfortunate that it failed, but
perhaps best let die, IMO.
 
kony said:
Though the values aren't critical, you might consider that
the caps already in the circuit, "may" be the failure point
and ideally would be upgraded. Also, you need consider the
diameter of the part, what will fit on the PCB and the lead
spacing.
Click to expand...
Good point. Another thing worth noting is that even caps of
identical capacitance and voltage rating may have different
physical dimensions.

Living in a remote location, I've often had to apply a little
ingenuity to solve similar problems. E.g., by drilling a hole or
two on the PCB to match the leads of the replacement part.
With a little thought it's often possible to make the new solder
point on the same copper track, thus eliminating the need for
jumper wires.
 
Good point. Another thing worth noting is that even caps of
identical capacitance and voltage rating may have different
physical dimensions.

Living in a remote location, I've often had to apply a little
ingenuity to solve similar problems. E.g., by drilling a hole or
two on the PCB to match the leads of the replacement part.
With a little thought it's often possible to make the new solder
point on the same copper track, thus eliminating the need for
jumper wires.
Click to expand...


Yep I do that sometimes too, taking an exacto knife to
scrape off some laquer exposing the shiney copper, then
drill a new hole. I do it more often to get a job done with
parts on hand though, in the OP's case the correct part
shouldn't be hard to find as there aren't that many
variations on snap-in monitor caps.
 
Back
Top