Question about Toshiba 57H81 57" Rear Projection Television

2 Answers

TOSHIBA 57H81 replaced conv amps and +- fuses set now fires without video. has horz and vert screen filament good. turn up screens get rgb glow with retrace. has good waveforms to the guns. 200v good. what am I MISSING.

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  • doug white Dec 30, 2010

    all the parameters ie; screen high filament 200 voltages are good as are the waveforms to the guns. I am missing something

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2 Answers

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  • Toshiba Master
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I assume you checked the waveforms right at the CRT cathode pins, not just at the input connectors to the CRT boards. If I read this correctly, if you turn up the screen, you get a uniformly illuminated raster on each picture tube, overlaid with retrace lines, with no picture, and you have sound from the video source.

If this is so, you have vertical and horizontal deflection (the original failure is repaired, more or less, with only adjustments left to do), and the presence of the blank raster implies both the CRT grounds and second anode connections are good. What's left are the focus, G1 and G2 voltages (one of the grid voltages sets the screen and the other the brightness limit). Perhaps the brightness limit is killing the gain of the CRT (wiping out the video signal). The question arises, how did that get broken? Look for a cable that was not properly reconnected after you put the deflection board back in. If you remember putting tension on a cable when you removed the board, (missed unplugging it the first time you tried to remove it), check the other end to make sure it wasn't pulled partway out of its socket.

Don't feel too embarrassed if this turns out to be the case- how do you think I thought of checking for it?

Posted on Dec 30, 2010

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  • Toshiba Master
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Change your tv dispalay screen
i hope this helpfull
please rate my answer

Posted on Dec 30, 2010

  • Lastoni Wibowo Jan 06, 2011

    change your tv dispalay screen
    i hope this helpfull
    please rate my answer

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Jul 11, 2009 | Toshiba 57H81 57" Rear Projection...

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Jan 23, 2009 | Toshiba 57H81 57" Rear Projection...

3 Answers

Toshiba 57H81 Flashing Red Power Light, Blown Fused F850+F852


Solved by resoldering some solder joints!!!!!!!
********
Toshiba Model 57H81 Rear Projection TV - Purchased 11-09-2001

Problem: Toshiba 57H81 Flashing Red Power Light, No Picture/Sound, Blown Fuses F850 + F852

Symptoms January, 2009:

  • Upon turning on set I got flashing red power light and nothing else.
  • Removing plug for one minute and plugging in results in:
    • Audible click, steady red power light for 2 seconds then slow flashing red light
    • Pushing power button results in steady red for about 2 seconds then slow flashing red light, no other set activity
  • Removing power cord for several hours and plugging back in made no change
    • Audible click, steady red for about 2 seconds then slow flashing red light
  • Possible related note: Over past several months occasionally the entire screen would flicker momentarily and at other times be problem free for weeks.
  • Fuses F850 and F852 found blown

Repairs Made:
  • PD0074 DEF/CON Power Board
    • There are two main power supply capacitors in this set. They are C-809 and C-810. One their negative lead on the printed circuit board re-soldered leads and nearby contacts. I’m told that because the factory left out a printed circuit board eyelet, the connection will come loose over time. When I called Toshiba customer service they said there was a known solder joint problem causing blinking red light.
    • Replaced blown fuses F850 and F852.
      • I actually installed a fuse panel on the inside of the cabinet and routed the fuse connections here instead of ordering the special fuses and replacing them on the circuit board.
      • Had to use a 5 Amp SLO-BLOW for F850. Fast blow does not survive power up. Get the red blinking light.
      • Used a fast blow 2 Amp for F852.
  • PD0073 SIGNAL Board
    • Re-soldered Q751 + Q752 STK392-110 Convergence Amps
    • Re-soldered adjacent pads that looks suspicious

Total Cost to Repair about $10
  • Twelve hours of my time over three days to research issue, disassemble set, make repairs, add fuse panel.
  • Already owned Service Manual and Circuit diagrams from a different 2004 repair.
  • Less than ten dollars at Radio Shack for fuses and fuse panel. Already had wires, etc.
  • Some solder. Already owned de-soldering tools, etc.
  • Visited both local authorized Toshiba factory service repair facilities. One said repair would have to include replacing Q751 + Q752 STK392-110 Convergence Amps with ST392-180, and realigning set for a total of $500+ and it would be more if they had to order a power board. NO THANK YOU! Other shop said $65 for site visit and $30 to make an estimate that could be applied to repair.

Jan 04, 2009 | Toshiba 57H81 57" Rear Projection...

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Toshiba 57H81


These ICs are the Japan types and available from partstore.com under part number C5AA00000108 for $29.08 + shipping apeice. These are original replacements for the panasonic parts. Good Luck Ps please do not forget to rate this

Oct 14, 2006 | Toshiba 57H81 57" Rear Projection...

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