Fuse F850 and F852 are open. They are part of the 16 volt and 32 volt supplies that are used by the convergence board. I still have not removed the power/def board but will need to. I believe the 32 volt supply is developed with a doubler circuit and both fuses being blown in the same area indicate the problem may be the supply components themselves. Capacitors, bridge or single rectifiers for example. Does anyone have any experience with this particular problem? Still haven't figured out how to disconnect the blue connector which connects the two circuit boards. The white connectors (2) disconnect and I assume the blue must have a similar mechanism.
Where exactly are the fuses? I am having the power light blinking problem all of a sudden. About a year ago I replaced the convergence ICs. The first fuse I see is the F850, and it is right behind where the power plug is attached to the power board. No problem with that fuse that I can see. I am gathering there are other fuses. It sounds like they may be around the convergence board. Any help in locating these fuses for inspection would be greatly appreciated.
Theres two jumper wires around the convergence ic's that supply the +/-32 volts to them.I found a cold solder joint on one of them.This causes the fuses to blow.Their close to the edge where the two boards meet.
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Re: Low voltage power supply fuses blown
If the convergence power supply fuses blew you can bet that the convergence ICs need to be changed. The blue connector will be pressed down on the rear of the connector to release or pulled up on the back end of the socket.
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Too many possibilities to predict if the fuse replacements will make the set function again but I suspect your main power supply has failed so if the fuses blow after replacement, you may have to have the supply repaired or replace it.
You might check, using your model number, at the site below to see if they have a power supply 'pull' available from their stock.
They part out retired sets of all kinds.
You have blown one of the pecos fuses, probably the f850 or f852, you can test them with the power unpluggrd and with an ohm meter. Replace them with only the recommended amps fuse. Your set is going into standby, because of the blown fuse.
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.
Check fuses on Power Supply board (F850, F851, F852) and all other fuses. Replace blown fuses (will need an ohm meter to check fuses). I would also replace the two convergence amps (STK392-110's on the signal board, the big black ICs on the two heat sinks). This worked for me.
ok well i would check for a open diode in the main ac to dc power supply then check all resistors that look lick they may be low ohms but high watt check to see if you might have a open pico fuse from primary power supply to the regulator check and see if you have stand by voltage this would be easily checked on the power off oan on button get back to me k
Well without the schematic, knowing Toshiba they have alot of convergence problems, so see if the fuse blown in the convergence area, if you you may have to replace convergence amps. These are the big STK's. Most of the time there was a color problem with set before going out. If no problem with this on your set then look in the HV area Hor. and Ver. area. Hope this helps!
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