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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

Reply to
Jason D.
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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.

Reply to
dkuhajda

HMMM! I would have, except this module does not use electolytic SMD capacitors like samsung does. Three filter caps (through holes and it's not the type to leak) for voltage planes bypasses, Rest are SMD ceramic capacitors.

Cheers, Wizard

Reply to
Jason D.

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!!!

Reply to
tvmirage

They are only saying to unplug the convergence yokes, not the scan/deflection yokes. Make sure you know which ones are the issue.

Reply to
dkuhajda

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