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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Wobbly vertical edges on iiyama Vision Master crt monitor
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. |
#2
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Wobbly vertical edges on iiyama Vision Master crt monitor
"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 |
#3
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Wobbly vertical edges on iiyama Vision Master crt monitor
"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! |
#4
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Wobbly vertical edges on iiyama Vision Master crt monitor
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. |
#5
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Wobbly vertical edges on iiyama Vision Master crt monitor
"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. |
#6
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Wobbly vertical edges on iiyama Vision Master crt monitor
"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. |
#7
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Wobbly vertical edges on iiyama Vision Master crt monitor
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! |
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