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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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RCA CTC169BG5 with focus problem
I have a 41 inch RCA tv with a focus problem. When adjusting the focus pot
on the Flyback I see little to no effect. Only thing you can see happening is a slight change in brightness. I also tried using the sharpness adjustment on the video setup menu as well with little change. Any suggestions? Should I change the flyback. |
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On Mon, 22 Nov 2004 11:07:02 -0500, "Rutro"
wrote: I have a 41 inch RCA tv with a focus problem. When adjusting the focus pot on the Flyback I see little to no effect. Only thing you can see happening is a slight change in brightness. I also tried using the sharpness adjustment on the video setup menu as well with little change. Any suggestions? Should I change the flyback. Either the flyback is bad, or the CRT has a short. Focus to G2 (screen) shorts aren't unusual. Try measuring the G2 pin on the CRT while varying the focus. If you see any change the in G2 voltage, try again with the CRT socket unplugged. If the interaction goes away with the CRT unplugged, the CRT is bad. If you have a meter capable of measuring to 10kV, you can try the same test on the focus voltage. If the CRT is shorted, it may be possible to save it. I've cleared a few by disconnecting the G2 wire and grounding the G2 pin while turning the focus to maximum. Sometimes this is enough to blow out the short. If that doesn't work, I've saved a few by grounding all the pins of the CRT except focus and applying an external HV source to the focus pin (with the CRT socket unplugged). Possible exposure to high voltages are obviously involved, so don't try this unless you know what you're doing. Andy Cuffe |
#3
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Are you sure you're adjusting the focus? I've never seen a 41" RCA, but most of
their larger 35" tubes use a dual focus arrangement, and the focus pots are not located on the flyback, they're on a small aux module, usually powered by a second wire from the anode connection. One pot focuses horiz and the other vert... |
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"Rutro" wrote in message alkaboutelectronicequipment.com...
I have a 41 inch RCA tv with a focus problem. When adjusting the focus pot on the Flyback I see little to no effect. Only thing you can see happening is a slight change in brightness. I also tried using the sharpness adjustment on the video setup menu as well with little change. Any suggestions? Should I change the flyback. Check for open C4503 CR5003,CR5004, CR5005 |
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