Tip & How-To about Televison & Video

How to fault find a faulty tv power supply

Get a mltmeter and test between live and nuetrol if there is a shot circuit, disconnect the capacitor from the rectifier diodes and test across the terminals of the capacitor if the same disconect the capacitor from the power supply transistor if the short is with in the transistor, replace it. if in the degoss, remove it.

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how do you test a diod in the circuit

First of all it is called a diode and it is an active component. The way you test it is , first remove power from the circuit, then using a ohm meter on the high power ohms or diode test function. It should read high resistance in one direction and low resistance in the other direction you also can use a battery and light bulb in series connected to the diode. The light should light in one direction and not the other. If the diode is across a coil or low resistance device it may not be able to be tested accurately in circuit, in this case one end will need to be lifted from the circuit to test.

Aug 07, 2014 | Electronics - Others

1 Answer

if the rectifier is defective would it chip tht circuit bbaker to the power source

Yes almost certainly if it (the rectifier) has gone short circuit, but you should be able to test the rectifier with a test meter; disconnect mains and rectifier, forward and reverse resistance should be low and very high for each diode leg in each direction of test leads (4 diodes if it has 4 wires)
test each leg both ways, or get testmeter with diode test

Jul 14, 2014 | Black & Decker 19" Electric Lawnhog...

1 Answer

wavy horizontal lines across the screen

It sounds that the main power supply section to your TV has the fault. The horizontal thik lines that appears crawling down across the screen should be of video 'HUM'. Have you replaced the main filter capacitor at the power supply section? If not, replace it along with the main rectifier. The AC power is rectifed by a bridge and applied ot this main filter capcitor. It will have a capacitance value between 120 to 350MFD 450VDC. Check this section. Measure the rectifed DC voltage acorss this main filter capacitor. It should be around 350VDC, if your home power supply line is 220VAC. If it is 110AC, this DC voltage will be around 165VDC; and it should be. If rectified DC voltage found lower than the input AC voltage, replace the rectifier bridge. In some sets, this bridge section have four diodes. Some other circuits, a bridge rectifier stalk may be used.

May 20, 2012 | JVC AV-27050 TV

2 Answers


theres a shortage in the circuit try check the rectifier diodes at primary power supply section, not dangerous to little knowledge,refer to a qualified service technician

Jan 03, 2010 | Samsung TXP3275H 32" TV

1 Answer

Hello I have a subwoofer and the fuse blew out. I replaced it with the same kind, but its still not working. The power light is on. When I turn it on it doesn't make that first thump sound. is it fixable?

It is very much fixable. Check if the fuse has blown again. And if it has, there is some problem with the circuit. Check conitunity across the main filter capacitor. If it's short, disconnect amplifier IC's power lines and check across the pins if it's short. In case it's short, you will need to replace the IC. But before replacing check all the rectifier diodes.

Dec 23, 2009 | Polk Audio PSW12 Subwoofer

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