Hans HG281D yellowed screen on top/center
Hello, Im having some problems with an HG281D monitor related to a yellowish tint at the center of the screen more to the top (please see attached photos). Second photo has some noise picked up by camera but it is not visible to the eye (not sure if the patterns give any clues).
The monitor had previously been dead (couple seconds then blanking out) and I recapped the power and logic boards except for the 12 small caps on logic board. After replacing the 5 100uf caps on the logic board the monitor came back to life but now has a yellowish tint in the center of the screen and more to the top. Not sure if I messed anything up with the recap job or this is a different problem.
Im starting to suspect something with the backlights, but Im not sure I can rule out the logic board or power supply?
I checked the power supply into the inverter (with the monitor on and displaying) and the voltage seems constant ~20v for the five sets of pins. Actually there are 5 vdd and 5 gnd and it seems a little odd that if I measure from the first gnd to any of the power pins I see 18v, but using any of the other grounds the voltages to the other vdd pins are the 20v.
Would appreciate any help to help narrow down if the issue is likely related to backlighting and if so how to proceed in debugging.
There are seven sets of white/pink wires that go to the backlights. This seems a little strange as it is an odd number, guessing it is a wide monitor so the top/bottom are probably broken up into smaller backlights. If there were two on top, two on bottom, one left, one right, this leaves one extra?
In terms of narrowing to tube or inverter issue not sure if inverter failure is a binary thing i.e. usually works or does not work, or could it also cause a dimmer channel.
Some ideas to try?
There are four 270uf 35v caps on the inverter that I could try recapping. Is this likely caps could cause this problem and any way to check?
Might be able to make some small extension wires and swap some of the white/pink wire sets/channels to see if the yellowing pattern changes?
Appreciate any help.
Kuma
The monitor had previously been dead (couple seconds then blanking out) and I recapped the power and logic boards except for the 12 small caps on logic board. After replacing the 5 100uf caps on the logic board the monitor came back to life but now has a yellowish tint in the center of the screen and more to the top. Not sure if I messed anything up with the recap job or this is a different problem.
Im starting to suspect something with the backlights, but Im not sure I can rule out the logic board or power supply?
I checked the power supply into the inverter (with the monitor on and displaying) and the voltage seems constant ~20v for the five sets of pins. Actually there are 5 vdd and 5 gnd and it seems a little odd that if I measure from the first gnd to any of the power pins I see 18v, but using any of the other grounds the voltages to the other vdd pins are the 20v.
Would appreciate any help to help narrow down if the issue is likely related to backlighting and if so how to proceed in debugging.
There are seven sets of white/pink wires that go to the backlights. This seems a little strange as it is an odd number, guessing it is a wide monitor so the top/bottom are probably broken up into smaller backlights. If there were two on top, two on bottom, one left, one right, this leaves one extra?
In terms of narrowing to tube or inverter issue not sure if inverter failure is a binary thing i.e. usually works or does not work, or could it also cause a dimmer channel.
Some ideas to try?
There are four 270uf 35v caps on the inverter that I could try recapping. Is this likely caps could cause this problem and any way to check?
Might be able to make some small extension wires and swap some of the white/pink wire sets/channels to see if the yellowing pattern changes?
Appreciate any help.
Kuma
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