TN50X81 - one convergence IC runs hot...TV powers off after 5min
I bought this set with a convergence issue...I replaced the convergence ICs (used the Sanyo parts, and the uprated 150 ones, too) and the picture came up fine. I could adjust the convergence and all seemed well.
But after running for 5min or so, the TV would shut off. I noticed that 1 of the convergence ICs was running HOTTER than the other. I've rechecked my soldering (looks OK...I'm an EE, so I'm not inexperienced in these kinds of repairs). I also checked the low-ohm resistors to the convergence ICs...all of these measured fine and showed no signs of overheating. I did use fresh thermal grease when fastening down the new convergence ICs, too.
Again, the TV is a 50' rear projection Toshiba TN50X81 made in March 2000.
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This kind of problem occurs due to failure of convergence output ICs in Sony KP-51HW40 tv. Replace convergence output ICs to solve tv problem.This set uses two of the STK-392-570 IC chips for this (convergence problem) Local tv repairman will do this job if you have no experience of electronics stuff repair.
Your TV is experiencing a convergence issue as indicated by the 3 blinks. The only way to fix this is replacing the convergence ICs. It is not a hard task to replace these ICs. You just need to know how to solder and work on printed circuit boards.
The convergence ICs are mounted on a large heat sink and are marked with codes starting with the letters STK and there are two of them. You need to replace both.
Look for the heat sink with two ICs mounted on it and check the markings.
Once found, cut the IC legs with a small side cutter and unscrew it from the heat sink. Remove the legs left soldered on the board.
Take note of the IC markings for ordering the right part and how it was installed. Don't forget to buy along with the IC a thermal compound.
Check the pico fuses on the same board. Most likely you will find a
blown one. These fuses look very much like a resistor, not like the
usual transparent fuse, and usually yellow.
Once you have the replacement ICs, put it on the board in the same way as it was installed before. Make sure the screw holes are aligned before soldering the legs into the board.
Put a reasonable amount of thermal grease/compound between the ICs and the heat sink and fix them with the screws.
Double check the board for any splash of solders that might cause a short circuit and damage the board.
The three blinks indicates a convergence IC fault. The convergence ICs must be replaced with the manufacturer replacement part. Use only the original replacement part. Your set uses STK392-110 convergence ICs. These ICs are mounted on a large heat sink. Yes, you can replace it yourself and save few hundred bucks. But you must be knowledgeable enough on how to solder, resolder and use a multimeter. You will need:
Heat sink grease or thermal compound
Small side cutter
Feel free to inform me if you decide to replace the ICs yourself
Replace the convergence IC's - P/N STK192-110 with part STK192-150 or 180. Then you can go back in and make the detailed convergence settings and get your picture back in alignement. Also check the flame-resistant resistors around the ICs to make sure that none of them have opened up.
Depending on where you bought the ICs you could have fried the new ICs when powering it up with burnt resistors as the green is controled by both ICs one IC controling the horizontal green Convergence and the other IC controling the vertical green convergence. Have you checked all the convergence resistors out of circuit?