Question about Toshiba 57HX81 57" Rear Projection Television

1 Answer

No power, LED blinking, Low voltage regulator IC?

Originally my power led would simply flash. After taking a look, I found fuse F850 open. Replacing this fuse worked for a while, but they kept blowing (usually after long periods of operation). Rather than trying to troubleshoot it further I replaced it with a bigger fuse thinking the component that caused the fuse to blow would eventually smoke (I know, probably not a good strategy). Something failed alright, although not visibly. At this point both F850 and F852 had opened. After replacing the two fuses, the relay clicks but the set doesn't power up. The power LED functions normally (the protection circuit NOT active) and I get nothing on the low voltage side or on the input side of the low voltage transformer. I'm thinking now I have two problems. The orignal problem that caused F850 to blow (perhaps convergence IC related) and now a new problem. Does anyone have any experience with failed low voltage regulator ICs going bad? Specifically I'm looking at Q801 (STR-Z4369). TIA

Posted by on

1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert who has answered 20 questions.


    An expert that hasĀ over 10 points.


    An expert whose answer gotĀ voted for 2 times.

  • Expert
  • 143 Answers
Re: No power, LED blinking, Low voltage regulator IC?

Check for bad solder connections then check all fuses the ones that look like resistors too get back to me

Posted on Nov 02, 2007

Add Your Answer

0 characters

Uploading: 0%


Complete. Click "Add" to insert your video. Add


3 Points

Related Questions:

2 Answers


if blink 6 time,ic regulotor is broken,you must repleace ic 6400 ic mcz3001db

Sep 06, 2009 | Sony Grand WEGA KDF-42WE655 42" Rear...

1 Answer

Low voltage power supply problem

Hi, I agree that the regulator IC is probably toast but you`ll need a service manual to figure the rest because none of the leds are on which means NONE of the secondary supplies are running, check the chemical fuses and I`m sure some will be open. you can go to encompass parts on the internet to order the sm, trust me you`ll fix it a lot faster, gl, video-tek

May 31, 2009 | Hitachi 55FX20B 55" 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...

1 Answer

Toshiba 65HX81 red blinking led

If HV comes up briefly,then TV shuts down = possible bad yoke and CRT...

If open fuse F850 / F851 etc = bad convergence IC's STK392-110

Either way = a major repair ! HTH.............................T.

Oct 22, 2008 | Projection Televisions

1 Answer

Toshiba 50HX81 Power LED Flashing

Check any/all soldered-in micro fuses....F850,F851 etc.
Re-check your work......
solder jumper wires on signal board or fuse (s) may blow......T.

Apr 20, 2008 | Toshiba 65HX81 65" Rear Projection...

2 Answers

Will not stay on

RED light is protect circuit = do not disable !
Look for C702 near flyback transformer - might be hidden in
glue = check it = if shorted, replace 102K / 2KV with 3KV =
Sony part # 1-161-754-00 and replace E994 pico fuse.....T.

Nov 08, 2007 | Hitachi 60UX54B/55K 60" Rear Projection...

2 Answers

No power

This model is equipped with a self-diagnosis feature to help with diagnosis of shutdown problems. To activate this turn the unit on let it shutdown then press the input/device and menu buttons on the front panel simultaneously and hold them in for 5 seconds after 5 seconds the power LED on the front panel will blink a two digit sequence. This will be one set of blinks a short pause then another set of blinks, this will repeat 5 times. 1 - 2 = no error detected 2 - 1 = X-ray protect (high voltage or beam current) 2 - 2 = Short protect (short protect monitors low voltage supplies) 2 - 3 = Deflection protect (this could be loss of vertical or horizontal deflection) 2 - 4 = Vertical protect (usually loss of vertical from the source) Hope this helps you!

Sep 14, 2007 | Mitsubishi VS-45607 45" Rear Projection...

1 Answer

No t.v.

Just a ?---When you say you checked fuses,does that include the soldered in micro-fuses?? 2)no power to the flyback is not a symptom-- could you describe what the set is doing or not doing? Is the red LED blinking up front,etc. Please advise-----need more info.

Sep 06, 2007 | Toshiba 42H82 42" Rear Projection...

2 Answers

Toshiba 57H81 circuit board removal

Post a Picture or the service manual here on this page and maybe someone can assist you.

Oct 08, 2006 | Toshiba 57H81 57" Rear Projection...

2 Answers

Flashing LED on front panel

The place is call ,you can get it download or a paper copy,for this set I dont know the price but it will give it to you when you put the model number.Check for shorted horizontal output and loose conections,sometimes intermitant conection damage this transistor.Be careful

Oct 04, 2006 | Toshiba 57H81 57" Rear Projection...

Not finding what you are looking for?
Toshiba 57HX81 57" Rear Projection Television Logo

Related Topics:

157 people viewed this question

Ask a Question

Usually answered in minutes!

Top Toshiba Projection Televisions Experts

Jaime Hernandez

Level 3 Expert

2267 Answers

Dave Naylor
Dave Naylor

Level 3 Expert

834 Answers

The Knight
The Knight

Level 3 Expert

66552 Answers

Are you a Toshiba Projection Television Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides