I have a Nanao MS2930 chassis which shows a partial vertical collapse on the bottom after turning it on for about an hour. I have sent it in to PNL twice and they can’t figure it out. The IC chip has been replaced, it has been recapped on the side of the IC, and it was checked to see if there were any bad solder joints. Not sure what else I can do here, but would appreciate anyone’s help and insight. Thanks in advance
- Thread starter Dkim28
- Start date
Looks like vertical foldover.
This usually indicates a fault in the vertical output circuit. It’s usually the IC, but It could also be a bad capacitor or other component in this circuit. It is probably caused by a fault in the flyback portion of the vertical deflection circuit.
I would test components in the vertical output stage or substitute for good ones.
This usually indicates a fault in the vertical output circuit. It’s usually the IC, but It could also be a bad capacitor or other component in this circuit. It is probably caused by a fault in the flyback portion of the vertical deflection circuit.
I would test components in the vertical output stage or substitute for good ones.
trashedcabs
Student
Is it only happening on your tube and not theirs? If so check your yoke--I had something similar happen on a Kortek which had the yoke windings short somehow, causing a strange horizontal fold.
What happens if you move the image upwards with the vertical position control? Does the image stay folded over or does it come up full? I've seen similar faults on other chassis, sometimes it's caused by a cap or the IC (but you say those have been done), but it also could be a power supply fault (as in the vertical ic not getting quite enough voltage). Or see if there's a tantalum bead cap in the vertical section. I've had those cause problems on two or three different makes/models of chassis.
Thank you for the suggestions! When I move the image vertically, it will come up full above where it is folded over. So in essence, the collapsed part on the bottom of the screen stays there, and I can move the image above and below it. I’m not sure what a tantalum bead cap is, and the power supply is at 4.7 which may be a little low, but I have 6 other identical cabs that run at the same or lower voltages and are fine. But maybe this monitor just requires more power now? It is driving me nuts trying to figure this out and I appreciate your help
