Hello all,

I have an iiyama Vision Master Pro 512 (HA202-DT) 22" crt monitor. The
image is distorted, giving wobbly vertical edges. The distortion is not
static, but is continuously moving, resulting in an unstable picture.
Photographs of the problem are available he

http://www.mijnalbum.nl/Album=7H37HISF

The amount of distortion is controllable with the moire compensation
control, but the control range is insufficient to eliminate it
completely. Furthermore, the distortion becomes worse over (operating)
time.

From a google search, I get the impression this might be due to bad
(dried) filter caps or general low-power-supply malfunction. But I'm
not sure this is the correct cause.

My questions:

1) Is this a well known problem, if so, what is it called (for further
googling)? Is there documentation available on this issue?

2) What's the most probable cause?

3) Is it easily fixable? How?


Thanks,

Alex.

"Alex" wrote in message
...
Hello all,

I have an iiyama Vision Master Pro 512 (HA202-DT) 22" crt monitor. The
image is distorted, giving wobbly vertical edges. The distortion is not
static, but is continuously moving, resulting in an unstable picture.
Photographs of the problem are available he

http://www.mijnalbum.nl/Album=7H37HISF

The amount of distortion is controllable with the moire compensation
control, but the control range is insufficient to eliminate it
completely. Furthermore, the distortion becomes worse over (operating)
time.

From a google search, I get the impression this might be due to bad
(dried) filter caps or general low-power-supply malfunction. But I'm
not sure this is the correct cause.

My questions:

1) Is this a well known problem, if so, what is it called (for further
googling)? Is there documentation available on this issue?


No idea. It's common enough in general though

2) What's the most probable cause?


My guess- ripple on the B+ supply.

3) Is it easily fixable? How?


Most likely the capacitor(s) which filter the supply to the horizontal
section need replacing. Straightforward enough job for anyone who has
serviced monitors or TVs.

Dave

"Alex" bravely wrote to "All" (19 Jan 06 17:02:31)
--- on the heady topic of "Wobbly vertical edges on iiyama Vision Master crt
monitor"

Al From: Alex
Al Xref: core-easynews sci.electronics.repair:355796

Al Hello all,

Al I have an iiyama Vision Master Pro 512 (HA202-DT) 22" crt monitor. The
Al image is distorted, giving wobbly vertical edges. The distortion is
Al not static, but is continuously moving, resulting in an unstable
Al picture.

Does it move smoothly up/down or jerking about at random?

A*s*i*m*o*v

.... If all else fails, hurl it across the room a few times!

Asimov wrote:

"Alex" bravely wrote to "All" (19 Jan 06 17:02:31)
--- on the heady topic of "Wobbly vertical edges on iiyama Vision
Master crt
monitor"

From: Alex
Xref: core-easynews sci.electronics.repair:355796

Hello all,

I have an iiyama Vision Master Pro 512 (HA202-DT) 22" crt
monitor. The image is distorted, giving wobbly vertical edges.
The distortion is not static, but is continuously moving,
resulting in an unstable picture.

Does it move smoothly up/down or jerking about at random?

It look as a random vibration in the horizontal direction. (Amplitude
ca. 0.5 - 1 mm)

Additional info: after letting the monitor cool down overnight the
picture is rock stable for a few minutes. As the monitor warms up, the
distortion increases.

So would I be looking for overheating components, or still for a faulty
capacitor?



Alex.

"Alex" wrote in message
...
Asimov wrote:

"Alex" bravely wrote to "All" (19 Jan 06 17:02:31)
--- on the heady topic of "Wobbly vertical edges on iiyama Vision
Master crt
monitor"

From: Alex
Xref: core-easynews sci.electronics.repair:355796

Hello all,

I have an iiyama Vision Master Pro 512 (HA202-DT) 22" crt
monitor. The image is distorted, giving wobbly vertical edges.
The distortion is not static, but is continuously moving,
resulting in an unstable picture.

Does it move smoothly up/down or jerking about at random?

It look as a random vibration in the horizontal direction. (Amplitude
ca. 0.5 - 1 mm)

Additional info: after letting the monitor cool down overnight the
picture is rock stable for a few minutes. As the monitor warms up, the
distortion increases.

So would I be looking for overheating components, or still for a faulty
capacitor?



Alex.


Get a can of component chiller (Freeze-It, et al) spray. Spray suspect
components in the affected circuit(s) one at a time till you locate the
thermally unstable part -- allow the chilled component to warm back up
before proceeding to the next one.

"Alex" bravely wrote to "All" (20 Jan 06 09:26:08)
--- on the heady topic of " Wobbly vertical edges on iiyama Vision Master
crt monitor"

Al From: Alex
Al Xref: core-easynews sci.electronics.repair:355909

Al Asimov wrote:

"Alex" bravely wrote to "All" (19 Jan 06 17:02:31)
--- on the heady topic of "Wobbly vertical edges on iiyama Vision
Master crt
monitor"

From: Alex
Xref: core-easynews sci.electronics.repair:355796

Hello all,

I have an iiyama Vision Master Pro 512 (HA202-DT) 22" crt
monitor. The image is distorted, giving wobbly vertical edges.
The distortion is not static, but is continuously moving,
resulting in an unstable picture.

Does it move smoothly up/down or jerking about at random?

Al It look as a random vibration in the horizontal direction. (Amplitude
Al ca. 0.5 - 1 mm)

Al Additional info: after letting the monitor cool down overnight the
Al picture is rock stable for a few minutes. As the monitor warms up, the
Al distortion increases.

Al So would I be looking for overheating components, or still for a
Al faulty capacitor?


Nope, if it is random horizontal it is likely arcing in the high
voltage, likely on or near the flyback. The warming up period is
simply the carbon track becoming more conductive with temperature.
Take a sniff around the back air openings when it is jittery, if it
smells acrid like electricty then that confirms it. You might even
catch a sight of the arcing with the cover removed in a dark room,
depending on how well shielded the flyback area is. A pocket AM radio
tuned between stations, brought around the back cover should also pick
up the static-like sound caused by the arcing.

What needs to be found is why it is arcing. One cause is an open peak
control network, off the horizontal output. This is often a small 2KV
capacitor with perhaps a resistor in series. If either one burns up,
the flyback pulse develops a narrow peak which has a higher than
normal voltage. Often the output transistor would breakdown and short
out but it seems this one can stand a much higher voltage.

Another cause would be a sync digital processing fault but less
likely. Good luck!

A*s*i*m*o*v

.... A fail-safe circuit will destroy others.

Degaussing posistor (positive temperature coefficient thermisistor) is not
disengaging (Stuck degaussing relay contacts?) Tap on it to see if it quits.

My 20" Viewsonic did this for a month or two, then just quit by itself.

Just guessing,

Mike Kinnaird

"Asimov" wrote in message
...
"Alex" bravely wrote to "All" (19 Jan 06 17:02:31)
--- on the heady topic of "Wobbly vertical edges on iiyama Vision Master
crt
monitor"

Al From: Alex
Al Xref: core-easynews sci.electronics.repair:355796

Al Hello all,

Al I have an iiyama Vision Master Pro 512 (HA202-DT) 22" crt monitor.
The
Al image is distorted, giving wobbly vertical edges. The distortion is
Al not static, but is continuously moving, resulting in an unstable
Al picture.

Does it move smoothly up/down or jerking about at random?

A*s*i*m*o*v

... If all else fails, hurl it across the room a few times!