Image with problem in Higscreen monitor

[bricoman]

My Vobis (Highscreen JD177P) 17" monitor has this problem. It works
...... but the image has a little(very complex to describe it)
movement. All works well like color, brytness, contrast, linearity,
pincushion correction, etc. etc. but there is a small orizontaly shift
right to left and back, and (i see)a low frequency vibration (??) very
very intolerant. The defect is present with or without computer signal
(in this case the image is static reporting same information about the
monitor). The degauss is ok, the TDA4858 and TDA4866 are good (changed
all), the KA3842 in the switching is ok (changed)all electrolitics
capacitor are good (with an ESR meter) and tha big ceramic high
voltage capacitor near the orizzontal yoke are good (changed).
Can somebody help my?
Many thanks
Alberto

 

[Jerry G.]

If you are sure you did not miss any of the bad caps with the ESR meter,
your only other solution is to use a scope, and verify the stability of the
power supply and horiz scan amplifier sections.

Look for noise or oscillations that are occurring at the rate of the
shifting or oscillations. I still have a feeling that this is from a
defective decoupler or some type of filtering cap. Check ALL the caps in
these areas with great care. Use new caps of the same type for comparing.

It is also possible that there is a cap failing only under voltage, and
since your ESR meter is using very low voltage to test them, this can be a
problem as well. Once in a while I have had this situation. Using a scope
to test the signal paths, and DC stability in all the areas may be the only
other way to pin this down. Or, recap all the these areas to start with.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
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My Vobis (Highscreen JD177P) 17" monitor has this problem. It works
...... but the image has a little(very complex to describe it)
movement. All works well like color, brytness, contrast, linearity,
pincushion correction, etc. etc. but there is a small orizontaly shift
right to left and back, and (i see)a low frequency vibration (??) very
very intolerant. The defect is present with or without computer signal
(in this case the image is static reporting same information about the
monitor). The degauss is ok, the TDA4858 and TDA4866 are good (changed
all), the KA3842 in the switching is ok (changed)all electrolitics
capacitor are good (with an ESR meter) and tha big ceramic high
voltage capacitor near the orizzontal yoke are good (changed).
Can somebody help my?
Many thanks
Alberto