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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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Help: Toshiba TV CM905C Vertical Fold Over
I have an old Toshiba TV, model CM905C, with vertical fold over at the
top during warm-up only. The top of the screen has 6-8 lines fold over, that gradually creep up and disappear behind the mask 8-10 minutes after power on. Turning the power off, waiting for a while, then on again, starts the same process over. I have checked voltages from the AC power supply to the horizontal and vertical sections and found them to be stable during and after warm-up. I have bridged various electrolytics in and around the horizontal and vertical sections with no affect or change in symptoms. I do not have a circuit schematic, so would welcome any suggestions on how to isolate the fault. The picture is otherwise great, good colour, good contrast, good focus. My concern is that something is about to breakdown and I would prefer to fix it now. Thanks in advance for any suggestions. Wally |
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Toshiba TV CM905C Vertical Fold Over
Wally Chopyk:
You are... or at least, were, on the right track. The culprit is probably is one or several faulty, high ESR electrolytics near and around the vertical deflection circuitry and output chip. Without an ESR test meter you can not easily determine which electrolytics are faulty..... at most, there are only a handful ( 6 to 8 ) of electrolytics in that area of the circuitry so you would be best advised to just REPLACE them all..... don't screw around bridging them or just guessing regarding individual electrolytics.. Your concern about fixing it now and about something is about to breakdown is absolutely correct. Immediately STOP using the television until you get it fixed. As long as it is "limping along" the repair should be fairly straightforward and economically feasible at most repair shops. If you wait until further problems develop the repair cost can easily be much more. If you are at a loss about how to continue the repair of this television you might consider taking it to repair shop, for at the very least, a repair cost estimate so you can make an intelligent repair decision with facts instead of internet or telephone guesses. If you take it to the repair shop AFTER aborted or failed home repair attempts the repair shop price could be more expensive. -- Best Regards, Daniel Sofie Electronics Supply & Repair ---------------------------- "Wally Chopyk" wrote in message ... I have an old Toshiba TV, model CM905C, with vertical fold over at the top during warm-up only. The top of the screen has 6-8 lines fold over, that gradually creep up and disappear behind the mask 8-10 minutes after power on. Turning the power off, waiting for a while, then on again, starts the same process over. I have checked voltages from the AC power supply to the horizontal and vertical sections and found them to be stable during and after warm-up. I have bridged various electrolytics in and around the horizontal and vertical sections with no affect or change in symptoms. I do not have a circuit schematic, so would welcome any suggestions on how to isolate the fault. The picture is otherwise great, good colour, good contrast, good focus. My concern is that something is about to breakdown and I would prefer to fix it now. Thanks in advance for any suggestions. Wally |
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