I changed the all power Mosfet transistors and two big filter Capacitor on the power supply board. There are no short circuit, I checked everything before I put the power in. When I put the power in, 6.3A fuse blown out and power Mosfet transistors went short circuit. Please somebody help. Thanks.

Short circuited component/s at its main power regulator board. Contact any service technician. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/

Try this: unplug the set and wait about 10 or 20 minutes. This is to make sure that the main power supply filter caps completely discharge. Look on the power supply board, close to where the AC cord attaches to the board. Look for a white resistor labeled "0.1 OHM" (the symbol for OHM, like an upside-down U) and measure it with your ohm meter. If it is open then your switching transistors in the main power supply are most certainly shorted. Older sets had 2 separate transistors on little heat sinks labeled "C4834", then they switched to 2 transistors in one package labeled "MX0841" or "MX0842", and then some sets went to two separate MOSFET transistors. Measure those parts and post your results and we will guide you from there.

Hi
our tv set need to be serviced. Here are some tips:
1. Open main fuse. The fuse is clean but interrupted. You can try replacing it with one o the same value.
2. Fuse Blown or blackened. Short in the rectifier bridge or in the switching transistor. Out of the power supply: supply line rectifier (100/150V) shorted.

Sully

you must have some diagram b) must test some around components like capacitor+diode+resistor+ic+Trafo , that will be in short circuit this will provoke the short in your MOSFET transistor.

God bless you

Hi,
Your fuse blown again because you have a short on the circuit. You may visit my link http://www.fixya.com/support/r8053361-fuse_keeps_blowing for more info.
I've suspect that you have short on rectifier diode/main filter capacitor/regulator IC/transistor. This is quite fixable.
Hope it may help you.
Thanks for using fixya.
JDVillanueva

It is power supply mistake. There are regulators fitted inside your tv circuit board, which are directly soldered to printed circuit board. After years of age, the soldering points gets heated and cooled, as the regulators will get heated while working. Re-solder the junction will rectify the problem.If it does not help check for any short circuit in it. A small value high voltage capacitor fitted to the collector of the horizontal output transistor, usually [330pf 2000v] will get shorted to earth. If it gets shorted it is an effect of direct short to the 120vDC power supply rails in your tv
or
There's a problem with the power ic board. Open it up and look for a burned capacitor. De-solder the piece out and replace with a new one that matches the same specs

i.e. bad capacitor in power supply

Hello

Your TV is now in dead condition I should say. You should strart from its power supply regulation section itsef to rectify the fault. Look into the fuse, a glass fuse is there, in power supply board. If It has found blown, make sure that there is something short in either power supply regulator side, of on the other part of the printed circuit board.
You just place a fuse of same rating as used, if the fuse is blown. If the fule you installed newly also blows off, check first the retifier stalk for any leak. The stalk contains four diodes, even any one of them gets shorte, fule will blow up. If there is no leak in the retifier stalk, measure the voltage resistance across the main filter capacitor, a bulky one capacitor fitted in the power regulator section. If you see a full deflection on meter, it means that there is some dead short inside the power regualtor system.
Usually Sony uses STR regulated type power supplies, and some uses MOSFET [Metal Oxide Semiconductor Field Effect Transistors], as switching elements. Bothe of these types can be shorted, due to a high voltage spikes, or a sudden supply failure and restart.
Check out short test on these components, out of board, that is, desolder it out from the circuit board. You just resolder one by one and measure the resistance ad described above. Thus you can find out the exact component, that have a short. If any of these components shorted, check the entire power regulator section for any more component failure, like zener diode short, resistors opened, and so on. You should have a concept of soldering and a little knoledge in electronics. There will be a MOV [Metal Oxide Varistor] fitted across the power supply input, which look like a disc capacitor. it will get shorted when a certain voltage spike occures abvve its rated voltage, and apply a dead short at the supply stage. If any of them used, desolder it out and check for any leak, and is found leaky, replace it. It is used as a saftey measure, and without it the set will work fine.
Just check these and if you find any difficulty, contact me through Fixya. Ok.

It may be in the safety shutdown mode if it sensing too much current draw. No short circuits in the inverter board. Plug it ino the wall out let and do not activate the power switch so the power supply will be running without having to power up the inverter board, if the 24vd is OK in the power supply then you may jave problem in the inverter board. How does the DC voltage on the secondary power supply side? Bad caps can look normal but it can have high ESR (Equivalent Series Resistance) which is a no no for switching power supply. Post back with more info. So far I cannot locate free service manual download for this model.

http://s807.photobucket.com/home/budm/allalbums
http://en.wikipedia.org/wiki/Capacitor_plague

Hi,
Components on the printed circuit board are still faulty, you need to carefully check the components on the board with the use of an ohmmeter.
Do follow the below procedures to enable you repair your television.
The click probably means that the power relay is working, though there could be bad contacts.

Since the fuse doesn't blow, you need to check for:

Other blown fuses - occasionally there are more than one in a TV.

Replace with one of exactly the same ratings.

Open fusable resistors. These sometimes blow at the same time or in place of the fuses. They are usually low values like 2 ohms and are in big rectangular ceramic power resistor cases or smaller blue or gray colored cylindrical power resistors. They are supposed to protect expensive parts like the HOT but often blow at the same time.

If any of these are bad, they will need to be replaced with flameproof resistors of the same ratings (though you can substitute an ordinary resistor for testing purposes). Before applying power, check: Rectifier diodes, horizontal output transistor, regulator pass or chopper transistor (if present), and main filter capacitor for shorts.

An initial test with an ohmmeter can be done while in-circuit. The resistance across each diode and the collector to emitter of the transistors should be relatively high - a few hundred ohms at lest - in at least one direction (in-circuit). If there is a question, unsolder one side of each diode and check - should be in the Megaohms or higher in one direction. Removed from the circuit, the collector-emitter resistance should be very high in one direction at least. Depending on the type, the base-emitter resistance may be high in one direction or around 50 ohms. If any reading on a semiconductor device is under 10 ohms - then the device most likely bad. Assuming that you do not have a schematic, you should be able to locate the rectifiers near where the line cord is connected and trace the circuit. The transistors will be either in a TO3 large metal can or a TOP3 plastic package - on heat sinks. The filter capacitor should eventually measure high in one direction (it will take a while to charge from your ohmmeter). It could still be failing at full voltage, however.

If you find one bad part, still check everything else as more than one part may fail and just replacing one may cause it to fail again.

Assuming everything here checks out, clip a voltmeter set on its 500 V scale or higher across the horizontal output transistor and turn the power on. Warning - never measure this point if the horizontal deflection is operating. it is ok now since the set is dead. If the voltage here is 100-150, then there is a problem in the drive to the horizontal output circuit. If it is low or 0, then there are still problems in the power supply or with the winding on the flyback transformer.

Other possible problems: bad hybrid voltage regulator, bad startup circuit, bad standby power supply (dried up filter capacitor, etc.) bad relay contacts as mentioned above. However, these probably would not have blown the fuse in the first place so are less likely.

The horizontal output transitor is always connected to the primary winding of the flyback transformer (via collector) and also to the horizontal deflection coil via an electrolytic capacitor. The most likely suspect for damaging the transistor is the fylback transformer. In some countries there are electronic stores that test flyback transformer by winding a few turns on the ferrite core and applying a test voltage. This test will only test the secondary. The primary winding is difficult to test for turn to turn short because the resistance is quite low and you do not know the 'good' resistance.