Question about Toshiba 53HX71 53" Rear Projection HDTV-Ready Television
This TV has an excellent picture (which is why we want to fix it and keep it) - except - it won't turn on. Point is, the set is fully operational and generally in good alignment except for this powering up problem. For some months, the set was turning it's self off, and then, immediately back on. In every instance it turned it's self off, the set would immediately, instantly, turn it's self back on. Sometimes, it wouldn't do the turn off and on thing for weeks. Then, it would go through a few day cycle where it would turn it's self off and on every five minutes. Then, it wouldn't turn off and on for days. There was no way to predict how often this sequence would happen but, over a period of months, it happened a lot. Giving it a few seconds to account for the soft start up, the image always, immediately, came back up with it's usual very good image. There was a relay sounding click clunk every time this off on sequence happened. If you looked very carefully at the red power light on the front of the TV, you could see that the red light did momentarily go off and then back on again. The red power light was off for such a short duration that you had to be looking at it before the set turned off or you'd be way too late to see it go off. The off on sequence happened very, very quickly. Then, one day, the set would not turn on at all. The click of the relay sound was there when you attempted to power up, but no picture, no red power on light. During the time the set was turning it's self off and on, the set would always turn on every time, without fail. Since the time it decided not to turn on, it has not turned on once. When it quit, it quit. I suppose that you, as an expert who is reading this, knows precisely where these power on relay clicking noises come from - but - just in case this helps.... At the very rear of the set, there are two large high voltage looking (just my idea of what it looks like) black bakelite? blocks that have large wires that look like car spark plug wires connected to them. The clicking sound appears to be coming from the smaller of these blocks. It clicks every time you try to power up the TV but the TV has never turned on since it initially failed. Once the set did not turn on, it was one and done.
I will tell you what I think it is.Note,high voltage,capacitors stay charged when tv is unplugged.Just don`t touch those ugly big things in there,lol.Now these circuit boards will unsnap,and come out,to a point.Some wires may need to be unplugged.They will only plug up in one spot,when you go back with them.Oh,and trust me,do not use a vacuum to clean it out,the dust,and debris is magnetical,it will ruin the vacuum,and electricute you.Blow it out(using face mask)with air pressure.Use googles too.Now when you pull these circuit boards out,look under them.You are looking for a burned spot.Look where the solder joints are,holding a heat sink,from the other side.This is a block looking thing,about 2 1/2 by 2 1/2,by 3/4 in thick.Has fins on it.This has a chip on it,that is on the heat sink.The burned out spot is a cold solder joint,this means bad solder job,from factory.Clean it with electric contact cleaner,that you can get at N A P A auto parts,or radio shack.Then re -solder the leg of the heat sink to the circuit on the board.The leg,looks like a piece of small wire,One stran of stiff wire.This solder was not holding contact,and melted away in time,causing it to short on,and off,killing the tv,and trying to work.Pull each circuit board and inspect under each one.I hope you find this problem,and it fixes the problem.If you need to ask anymore questions,please ask,thank you,if this was helpful,please let us know.
Posted on Dec 12, 2009
From the description of the problem and sequence of events, it seems that the power supply unit has gone finally. It started giving trouble long back and finally it just died. Please replace the whole PSU as replacing only the relay or whatever will not do in the long run. If you change the whole module then you could use it with confidence. PSU can be located where the power cord is joining the small PCB. This PCB would also have a small transformer on it. It would be easier too. OR, should you feel confident of your soldering skills then go ahead and replace the what you describe the bakelite looking block. But make sure you have exactly the same specifications stuff as replacement.
Posted on Dec 12, 2009
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Posted on Jan 02, 2017
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