KDS XFlat 19" CRT out of focus

[dood]

I've got a CRT here at work that suddenly went out of focus this morning. Any thoughts on causes, and if it can be fixed? IF it were a 15 or a 17, I wouldn't bother, but the 19 might be worth it if it's an easy fix.

[Spacedye69]

Re: KDS XFlat 19" CRT out of focus

If it suddenly went out of focus as opposed to a long, slow dimming/ fuzziness, its probably low voltage on the 140v. Check the caps is the ps section for a 160v-200v around 100uf to 300uf.

[dood]

Re: KDS XFlat 19" CRT out of focus

brightness is still fine... it just suddenly went fuzzy.;

[Maxxarcade]

Re: KDS XFlat 19" CRT out of focus

I have a 17" KDS that did the same thing. It has a very touchy focus knob on the flyback. Maybe that is the problem you have as well. Check solder joints and caps while you're in there too.

[Krankshaft]

Re: KDS XFlat 19" CRT out of focus

The reason your focus went fuzzy is because the focus voltage supplied through the flyback dropped.

If the brightness is still fine try turning the focus POT on the back of the flyback with the monitor running. If that fixes it close it up and let it run and see if it slips back out of focus again.

It could be that one of the resistors inside the flyback voltage divider bit the dust causing the voltage to go off.

It couldn't be the supply voltage if it was the brightness would have dropped too.

[linuxguru]

Re: KDS XFlat 19" CRT out of focus

There's probably a bad joint or bad cap somewhere in the flyback section - start by reflowing all beads that look dry or suspect. Then think about replacing caps.