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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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Let talk: TN50X81 (chassis TAC9960), convergence stuff
Hi all, I have a set in for "shut down" with LED flashing. Quickly
traced to the "protect" pulling up on shutdown. Tried convergence power disconnected and tv fired up. Bingo. Unsoldered both STK392-110 IC so I can make sure the convgerence generator module (stand up long retangular metal box) is outputting six correct signals to STK392 ICs. Aha several were badly distorted or almost gone, except two out of four were good. Opened it up showed several ICs and pulled down two datasheets on both ICs. Other than that, one big square SMD Toshiba IC. Will finish isolating to specific IC failures tomorrow hopefully. Six PCM56P (D/A converters) Three MC33079D (Quad opamps) Which IC is most likely to fail? MC33079D or PCM56P? This is remarkable that I did this without schematic. Cheers, Wizard |
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IC? Most convergence module failures I have seen were due to the
surface mount capacitors. If it has then, ESR all of them before replacing any ics. |
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Hi Jason!!
Well, im new to this forum....hopefully I can help!!...your problem is probably the eeProm IC in the Digital Convergence, QH174. I laso have a service Note from Toshiba. Model:TN50X81 Fault: Set in ShutDown Mode Bulletin: 1) Unplug the red, green and blue convergence yokes from the convergence output board. 2) If the set then fires up, replace the QH174 Eeprom and set up the convergence. 3) Resolder the convergence output board and clean P726B plug and socket using a fibre glass brush. This will remove any tarnish that can cause the convergence to change. Im not sure how safe it is for the CRT's to unplug the yokes, I burnt a tube in the past cause of that but form what oyu mentioned...the eeProm is faulty. Replace and align Convergence...good luck!!! |
#5
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They are only saying to unplug the convergence yokes, not the
scan/deflection yokes. Make sure you know which ones are the issue. |
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