problem in sun GDM 20E20

Does red work in the OSD or is it missing there too?

This may be a signal loss in one of the video processing stages. You would have to go through the video paths with a scope to see where the signal loss is. There are many components that can cause a failure as what you are describing. The fault can be a failing component or an intermittent solder connection.

I would suggest giving out the monitor for proper service. Considering its age, it may not be worth the cost.

Probably a dead resistor on the neck board. IIRC there is a divider resistor for each color on the board. The other less repairable fault is dead emission in the tube, you can partially bring them back to life with a regenerator box. tapping the neck and the video drivers can detect a dry joint which is also a possibility. If you don't have experience doing HV repair don't touch these monitors.

Andrew

I had a monitor with the same symptom after it had been in use for about 2 years. Whacking the side of it would cause the colors to flicker. Found a transistor with a cold solder joint in the area Andrew (above) mentioned. Again, be careful around that high voltage. Rush.

i hv checked for cold solder but i hvn' found any cold solder . i gave my monitor for repairing in my city but he couldn't found exact problem in it . he told me there is problem in color processing IC. but i don't know which IC processes the color.

I think tube is ok bcoz i hv changed the board which connected to back of tube. when i interchange the board the problem is also interchanged.

Can any buddy tell me which IC may be faulty

thanx in advance every buddy

red is not working in OSD

Sounds like this monitor uses an IC to drive the cathodes directly, this IC has apparently failed. Is there a large heatsinked IC on the neck board?

Its a monitor not a TV, so no color processing IC as such. In the ones I serviced there is basically various boards with the 75 ohm in that would then connect onto the board at the back of the monitor with various video amplifier chains some using video amplifier blocks others using transistors these would then make their way onto the neck board and into the tube. You can isolate the amplifier chain by swapping the BNC in lines. And if it is known dead then trace through the above chain with a color pattern, which you can load off the net.Another resource is the S.E.R F.A.Q. from this group.

Andrew

hello Andrew

there is two IC one is CXA 1907S (SONY) and other is FA1401 (HITACHI) (with large heat sink) can be problem in one of them IC?? cause the signal goes to CXA1907S directly plz tell me abt it.

thanks

Just redirect the interconnect leads to isolate the problem.

Andrew