Insignia NS-LCD19-09 (third and final post, hopefully!)

[valvashon]

I have been going round and round with this one for a couple of years. It's a 16x10 display that allows you to size your OTA picture correctly to 16x9 and that makes it kind of cool so I really want to keep it on my OTA monitoring wall. Accidentially let a screw roll under the powered power supply board and ended up replacing the MOSFET drivers for the inverters, then one of the Schottky rectifiers for one of the supplies, then the PS caps becuase I fired the parts cannon at it one day.

Problem was no cold startup; it would only startup when you applied a heat gun to the board. Without the heat it would get as far as a flash of picture, then go off again. Finally traced that down to the "blue" high voltage/low value caps in the inverter circut for one of the lamps. Two of the caps for the non-affected circuit/lamp are fed directly from the power transformer, the side with the problem seems to feed a voltage sensing circuit that won't let startup happen/finish if something is wrong with one of the lamps. The two caps for this circuit are fed by a third cap which checks as having no value; this obviously changes with heat applied and the TV will start up and run all day. If the TV has been on for a while it will start up again so I believe that the problem is with that cap, which should be 2pf/6kv (C817 in the picture).

I will be replacing all 4 blue inverter caps and C817. I would also like to replace one of the lamp sockets on the board (burnt pin as shown) but can't find them anywhere. I know these are kind of standard, does anybody have a part number or a good term to use in a search?



Thanks

Val

[Davi.p]

The electrolytic cap next to 0835 "lcd style" mark seems to be original and poor brand one, better to change it, the lamp connected to the top section seem not so well since the circuitry near the connectors seem to have suffered, better to think to replace it if the expence is not too high, but if lamps has not dark ends then are ok,.conector is not ok, it you can grab an old lcd from the landfill them are near all same type (small.size lcd)

[Diah]

wait, i saw this PSU boards before all caps at Cold are black one,, but you have blue and red... this is huge different... show please the downside of the boards

[valvashon]

OK, there seems to be some confusion about this board and what I have done to it so far. The 4 capacitors in the 5 volt and 12 volt supply have been changed out during "parts cannon" day. The two tall black ones are 470 uf/25 volt Panasonic caps, replacing C915 and C922. C915 was 470/16 and the old one currently checks at 441uF. C922 was 470/25 and the old one currently checks at 458uF. These two black Panasonic capacitors will stay in place. The red one is a 330/16 volt "Wurth" capacitor replacing C917. The old C917 currently checks at 345 and will be put back in the circuit once the problem has been repaired. The blue one is a 680/16 volt Philips capacitor replacing C930. The old C930 currently checks at 694uF and will be replaced once the problem has been repaired.

I can find no evidence that C908, C812 and C905 have been replaced. I will recheck their values once the problem has been repaired. C812 (next to the "0835" mark) is a 1000/25 volt Mallory capacitor and unlikely to be bad as Mallory is a respected manufacturer of electrolytic capacitors.

With the addition of a very small amount of heat from a heat gun directed right at the blue capacitors C817/C819/C820 (through a paper tube) the TV will start up with no problem and once up and running, the picture quality is excellent, clear and bright with no dark spots. I have not examined the CCFL tubes but I don't believe that they are bad or going bad.

More tomorrow as the parts arrive today.

Val