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On the power supply board transistor labeled VB40 was fried, and the part number is totally illegible. I do not have a schematic for this set. Can someone tell me the part number for this transistor, and maybe an Thanks ECG sub number ?
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Is it possible a fuse is blown or the circuit board is fried? Did you use a power supple with a higher voltage then the TV needs? If so, replace the boards and the fuse, than use a correct power supply. DO NOT USE A POWER SUPPLY THAT HAS TOO HIGH VOLTAGE! Check the label on the back/side of the TV. Fine where it says "input". then take note of the voltage number. Then, check your power supply. When you look at the power label on the power supply, look at the voltage on the output part of the label. If it is higher then the input voltage on the TV, DO NOT USE THAT POWER SUPPLY! IT COULD DAMAGE THE TV! Hope I helped!
although resonace does not always indicate power problems that would be the first choice.. i would say 80 percent chance that the power board is bad.. but theres always a chance that one of the other boards or even the panel could be loading the psu down
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.
Ur tv have a total power supply board failer.That the board where the tv power a/c cord plug into it.Tries websites like Shopjimmy.com,Ebay.com to buy a whole refurbish power supply board for the replacement.
Look for a fried (possibly exploded) transistor or diode on the power supply board. In particular, look at the transistor mounted on a heat sink (metal radiator block) between the fuse and the largest transformer on the board. It may also have a damaged regulator chip driving it. Modern TV sets operated by remote controls generally have the power supply split into two sections
- standby and main. Your problem is most likely in the main section.
A voltage sniffer won't tell you much - most sets have power right up to the fuse on the power supply board. If the fuse is blown, don't bother replacing it until you find out what blew it - you'll just waste another fuse. I generally start by doing ohmmeter checks (power disconnected!) on the diodes and transistors - anything reading less than 1 Ohm is probably fried or is being shorted through a transformer winding by another fried component. Other readings must be interpreted according to the circuit design.
In the Polaroid FLH-3701, the fuse is located on the power supply board, next to the AC power connector. It is a small black cylinder. It is labelled F1. Value is 5 amp, 250 volts.
A fuse does not blow for no reason. Most commonly a fuse will fail because of a short someplace on the board. I have this same TV. The fuse blew. The reason was transistor Q6 had shorted. There are two identical paired transistors on the output side. Q6 and Q7. They are both Infineon 11N60C3 MOSFET transistors. Check those for a short. There may be a burnt smell.
More commonly, this TV will fail because of bad capacitors on the power supply board.
Power Supply never burn fuse these day,they have so many transistors,ics,capacitors,resistors so small any thing could be burn,never find out almost impossible.The power supply board is dead,must replaced the whole board.
Dead, led flashing red/green at first, then going to red standby
Replace C604 (1000uF, 16v) elec. cap. It is in the decoupling circuit for the 5 volt supply
Red led blinks on / off, TV does not turn via power button and/or remote but after 20 minutes or so it turns on and works fine
Replace R902, R901, R905, R903, R900A, Q902, and possibly the two (one
small and one large) capacitors in the section labeled as the power
supply. The board will be black under the components that are bad. Q902
is an NPN transistor and is hard to find.
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