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).
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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
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
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.
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.
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.
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!
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.
The place is call wwww.servicemanuals.net ,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