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Your IC's on yjur convergence board have failed. The convergence board is accessed through the front of most projectors.You are looking for two devices with a number like STK 392-110 STK 392-150 or STK 392-180. These devices solder in, You may also find a burned resistor or two, and there may be a small fuse blown in the circuit. (not all have a fuse).
I've found some this i nfo that could help you troubleshoot your TV.
Your problem is likely to be in the convergence board power supply p/n 250868. May not be supplying the - and + 15 volt supply, abd the +45 volt and - 45 volts account shorted diode cr19710. p/n 164590. also replace cr19709 the one next to it same part #. Also if stk730-130 is bad it can cause this problem. Also check r 19703 (750k 1/2watt) may be open, q19700(bc457)or nte123a could have base emitter open.
you must have a toshiba tv. easy. with the back off, you will see 2 convergence ic's mounted on big silver heat sinks. and they will say on them stk-393-110. replace both of them. unplug tv of course. unplug all plugs on that convergence board. unscrew the two screws that hold it. slide it out. and then replace them on a work bench by unsoldering the stk's, unscrewing them from the heat sinks. replace, solder in the new one's, screw in the heat sinks back, slide the board back, plug in all the plugs back, then enjoy
Hi, This sounds like the most common thing that fails on projection TV's, regardless of the brand. The convergence circuit has two, or sometimes three STK IC chips mounted on heat sinks to drive the convergence yokes. They typically last anywhere from 5-10 years, then they fail.
It sounds like in your case, the solder joints on the bottom of one of these chips may be failing and some fresh solder will make it go for a while. I would recommend you to replace both the STK chips. These ICs are used to align and keep aligned the three colors on the screen...
INSTRUCTION TO REPLACE CONVERGENCE ICs:
The parts you will need are two ic's that are referred to as STK ic's. This is in reference to the first three letters of the part number. You will also need some pico fuses. The pico fuses are little yellow fuses that look like resistors. When they blow, they will show no physical sign of failure. The amperage rating will be printed on the fuse. For example a 5 amp fuse will have the number 5000 on it. A 3.15 amp fuse will have the number 3150 on it. You will need to use an ohm meter to test these fuses
The stk ic's are on the "D" board, attached to large heat sinks, When looking from the back you can see the heat sinks but the part's themselves will be pointing away from you and hard to see without removing the board, or using a mirror to look at the part numbers. The fuses are generally located under the fins of the heat sinks. There are several of them and vary by model. On the "G" board there will be two yellow pico fuses near the connector going to "D" board. These fuses provide power to the stk ic's you must check these as well.
When replacing the STKs make sure you use heat sink compound on the back of the ic's before installing them. Also as a rule of thumb, screw or clamp the ic's down to their heat sinks before you solder the pins. Replace any blown pico fuses and re- install your boards. When you turn your set on it may still be out of convergence due to many factors. Try pressing the auto focus button on front of your set.
You don't need to replace the whole board, regardless of which board it may be mounted on. The STK IC convergence chips alone are all that need to be replaced. You can order them from a number of different online sites. You can try Alibaba.com. If you have any more questions, feel free to ask!
I dont recommended buy convergence board.... Time to fix it !!. Replace two Ic's Stk 392-110, and get in service menu settings , and adjust point by point. After replaced stk IC's, check if any resistor look brown or born, if yes, replaced it with 6.8 Ohms. If you have questions? email@example.com . Good Luck !!
Replace the convergence IC`s again using original Sanyo chips (STK 392-110 or STK 392-180). Make sure to use plenty of heat sink compound. Coat the entire back side of the chips. Also look to see if any of the low ohm resistors are burned. A shorted chip will cause the thumping sound and the set will shutdown. I am guessing that you used generic IC`s as a replacement. They are cheap and the leggs fall off when you apply too much heat during soldering. Dont wory about the CRT driver or the deflection board, they are probably fine.
Your problem could be the Convergence board is loading down the power supplies and will not let the TV set come on, or the power/deflection board, part number AA94-08574A, or the STR type regulator IC, part number
AA13-00105A. If you locate the convergence board, unplug the connectors, and see if the set will come on. if the set does come on, replace both of the STK convergence IC's at once. The part numbers for those IC's are STK392-40. You can get the original replacement IC's from MCM electronics for about 15 to 16 bucks a piece. Do not use the less expensive STK IC's as they are not the same. the replacement IC's should have the name of SANYO printed right on the face of the IC's. Good Luck
The red convergence amp has probably failed and both STK's should be replaced, along with two or more of the 3.9 ohm fusible resistors in the circuit.
This is one of the more easily repairable units in the Samsung line because the convergence circuit is a separate board mounted up and away from the signal and deflection boards.
But if you're not too tech savy don't tackle this yourself.
Icz103 and Icz104 are both STK392-040. Check and possibly replace both FD101 and FD102 pico fuses (3.5 amp) and check all 3.9ohm/1w fusible resistors. At least two of these will be open when the corresponding STK failed.
Replace the STK's with Samsung parts or genuine Sanyo STk's not their JApan knock-offs which are VERY hard to tell apart. And use a good heat sink compound when mounting the IC's for proper heat dissipation.
If you have any questions let me know...
PS: Many Techs have taken to mounting fans on this board to cool the IC's... Fans have proven to reduce operating temps by as much as 40 degrees and extending the IC's life limit by as much as 50%...
no sundog this model has the potenthal to be a nice tv when you saw the burn't resisters that was your clue to change the stk's now that you have fixed the res problem the bad stk is telling the set to shut down replace stk,s i ALWAYS change both (buy the way in the future those are hi watt res THEY SMOKED FOR A REASON maybe you thought they were installed in the 70"s ha ha. but they smoked because the stk's one or more are bad.
good luck doc