JVC AV32S575 32" NO POWER DEAD!

[wad2k]

Hello,
I have a JVC AV32S575 32" (fairly new 1-2 years old) that is dead no power at all no sounds coming out of set when I plug it in. I already checked the one fuse I did find by the line(power cord) in and it is good. On that board there is 2 transformers a couple caps and 2 connectors+ part K9901. I'm assuming they are isloation transformers. I removed that board. Checked the voltage at the one connector and it is good 117V. From there it goes to main board. Not sure what the other connector on that board is for. It is 5 pins and looks like it is connected to part K9901. not sure what it is.

I would think that borad is fine so what next?

I do have alot of electrical experience but more on the design end.

Hope someone can help me. FAcing a possible layoff at work so right now I have more time than money and I would sure like to fix this myself. No Disney channel for my 2 and 7 year old daughters..They are bouncing off the walls! CAn anyone relate? LOL

Id be happy to send any pictures of the boards if someone is willing to work with me on this.

Thanks in advance!

Wade

[Guest]

Maybe you could sell your daughters and buy a big screen? LOL

Sorry:)

I am not familiar with your T.V. as I have never heard of them in this country. You have a fuse, a commonmode filter, a rectifier and a Mains capacitor. This may be the biggest electrolytic on the board. You should get about 320 volts across this capacitor which is the supply for the chopper/switchmode. CAREFUL, if the chopper is open, this capacitor can remain charged so carefully discharge it with a lightglobe or resistor. Unplug the T.V. and measure this first.
They don't have isolation transformers in the supply so you will need to plug the unit into one before connecting any test equipment. There may be a small transformer for powering the unit while in standby (so you can remotely switch it on) and the main chopper transformer for producing the main voltages for the T.V. It is likely your problem is here so test the chopper transistor with your ohm meter.
The chopper transformer switches at high frequency to produce a big voltage from a small transformer, the main voltage, called B+ is about 100 volts and feeds the Horizontal Output Transistor (HOT) near the Line Output Transformer (LOPT) which may be a big black plastic thing with a sparkplug lead going to suction cup on the back of the screen. Another

WARNING - BEWARE of the 30 000 volts or so that is stored here, don't touch the suctioncup unless you discharge it with a high voltage probe!

The Horizontal Output Transistor should be the biggest transistor on a large heatsink near this LOPT, it basically switches the B+ voltage on and off at 15 625Hz to a winding in the LOPT, the other end of the winding being grounded to the B+ ground. The LOPT induces all other voltage rails for the T.V. and again, it is likely your problem is here. Measure the Horizontal Output Transistor for shorts but remember that it has a diode across the output and internal resistors on the base.

Maybe your LOPT has burnt out, shorting out the HOT and chopper transistor or maybe it is only the chopper startup resistor that is open.

Now it is time for you to have some fun, let us know how you go!