Focus problem on old VDT

Jan 12, 2006 2 Replies
B

I've got a NEC Multisync-II VDT (JC-1402HMA), about 10-15 years old. Brightness and contrast are OK, not stunning. But when cold, it's badly out of focus and becomes acceptable after ~10 minutes as it warms up. I can twiddle the focus adjustment to get good focus when cold but then focus is bad when warm. Brightness/contrast don't appear to change much as it warms up.



Is there any particular component or two which would fix the problem? I've got the service manual so I won't be totally in the dark.



Thanks


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J

Common causes are from the high voltage multiplier, and the CRT itself is going weak. The high voltage multiplier may be a separate module, or combined with the flyback, depending on the chassis type.

As components age, some may become thermo sensitive, and change their specifications with temperature, age, and use.

Depending on the exact nature of the fault, this monitor will most likely not be worth for to have it serviced.

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JANA _____

Is there any particular component or two which would fix the problem? I've got the service manual so I won't be totally in the dark.

Thanks

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Y

Bad filter capacitor in focus voltage/high voltage stage ?? pulling down focus/high-voltage voltage.

Yukio YANO

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