Question about Toshiba TW40F80 40" Rear Projection Television

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Toshiba tw40f80, replaced both convergence ic's, power light still blinks

My toshiba tw40f80 is still going into protection mode after replacing both convergence ic's and checking all fuses with a multimeter, all fuses in the power supply checked out good, I used stk392-180's after reading their spec sheet 18 watts versus the original stk392-110's which were 11 watts, the tv is still going into protection mode after the high voltage supply for the crt's tries to come on, where should I look next? Also, where can i get a copy of the service manual for this tv?

I looked carefully at the spec sheets for both of these SIP's and the 180s should be fine in place of the 110s although the circuit toshiba is using has 2 ohm resistors in place of the 3 ohm suggested by the data sheet, should I swap out the 2 ohm for 3 ohm resistors?


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  • grassulo Aug 03, 2008

    checked vertical convergence ic connections and all 3 yoke plugs all check out fine, the tv goes into protection as soon as the hv supply tries to come on, i can hear the high frequency it briefly makes then it clicks off, could the problem be in the base power supply? like a failed electrolytic cap or bridge rectifier?

  • grassulo Aug 04, 2008

    i unplugged the protection circuit as the service manual states in its conversion diagnosis flow chart, i can adjust red and blue convergence fine but green is immobile and bowed horizontally in at the top and bottom of the screen, im going to re flow the solder on the horizontal convergence correction ic and see if it will allow adjustment then.




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Solder yoke plug and vertical IC connections.....try again.
Let me know.....T.

BTW....Tosh recommends STK-392-110's replace with -110T's
Toshiba OEM.....then there is no question about resistor value

Posted on Aug 03, 2008

  • Vista Electronics Aug 03, 2008

    Solder Vertical Output IC connects....

    Replace convergence IC's with Toshiba STK392-110T....

    Part # 23135090........some Tosh TV's are picky.....

  • Vista Electronics Aug 03, 2008

    Check all fuses, F850,851,etc...............T.



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1 Answer

Toshiba tw40f80 cannot adjust green and blue

ok, if you do have a sound problem it is separate from the convergence trouble; this set uses two STK-392-110 ic's. you need to change both and any of the resistors near them that may be gone or open---then adjust the set with the original remote--you can do the adjustments in the customer menu or if needed in the TECH menu-I can tell you how to get into that menu--if you have no sound from the speakers in the set that is a separate issue.

I do this here for free--if you have questions or need help reply here--if this has helped you give me a vote here.

Most of these sets with a convergence problem just need the two chips replaced and the set adjusted---you can buy both chips on Ebay for less than 14 dollars plus shipping.

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You will first off need to get the training manual on this TV set, so you will know what this set is all about. The problem you have with your set is the convergence IC's need to be replaced, then you will need to understand the service manual so you can go in without destroying the set, and make small convergence corrections. The training manual is available here You will need to know how to solder, as well as certain terms used in this training manual. If you have no electronic background, I highly advise that you call in a pro to assist you in the replacement of the IC, but have this manual available to the technician, as it might save you a few bucks. Good Luck with this repair.

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In this unit it's likely the convergence amps are the cause. Those and possibly the 2.2ohm resistors (especially R7726) in the yoke return path - that's why you found the open fuse.

William Rayburn, CET
Premium Technologies
PO Box 442
Long Beach, WA. 98631

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1 Answer

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Check soldered-in micro fuses in power supply. Ex.--F851,F852.
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Need more help? Let me know.....T.

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