Help with no backlight on Toshiba 42AV504D

[Mikeyboy2007]

hi guys got a TV Toshiba 42AV504D swithced it on and got no picture, shined a light up against it and seen a picture so then realised the backlights where not on. i opened up the tv and the 2 caps that where on each inverter board (one at each side) where bulging like mad so i replaced them. put them back in the tv but still no baclights. one of the numbers on the boards are LC420WX7 and someone is selling a repair kit on ebay for this type of board. worth while or could it be something else. heres the link to ebay listing http://www.ebay.co.uk/itm/LCD-INVERT...item3f17ddcd88

and the picture of the 2 boards after caps replaced.

[tom66]

Re: Help with no backlight on Toshiba 42AV504D

Checked the fuse on it? The FETs can fail on these.

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

took advise tom and got a better camera no will check the fuse on both the inverters and what is the FET tom66 ?

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

Tom66 switched on tv, set multimeter to 20v tested both fuses both ways and got 0v all the way ??

[tom66]

Re: Help with no backlight on Toshiba 42AV504D

It's a 24V inverter, you'd use the 200V range - anyway, I'd just check continuity for now, on the ohms range (2000 ohms.)

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

sorry Tom, you must think im a total pain in the ar*e but how do i do that ?

[vinceroger69]

Re: Help with no backlight on Toshiba 42AV504D

post a picture of your multi meter then we can advise you on the settings.

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

its not the best multimeter

[tom66]

Re: Help with no backlight on Toshiba 42AV504D

Switch it to the 2000 horseshoe ("ohm") range then measure across the fuse, you should see less than about 3 ohms.

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

do i do that with tv on or switched off.... probably a daft question but just to make sure

[vinceroger69]

Re: Help with no backlight on Toshiba 42AV504D

off hahaha not a daft question at all.

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

vincegregor69 tried doing that both ways on both boards and the numbers flash twice then go to 1 , i tried more than once and the numbers are never the same ??

[vinceroger69]

Re: Help with no backlight on Toshiba 42AV504D

what reading do you get when you hold both multi meter leads together?

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

flashes up 2 different numbers then goes to 000. then when i take them apart it goes back to 1

[vinceroger69]

Re: Help with no backlight on Toshiba 42AV504D

maybe time to get a better multimeter imo anyway see what tom suggests too i suppose you can set your multi meter on 200v dc and put black probe on chassis and red on each side fuse and see if you get any reading? tv turned on when testing.

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

ok will try that and update you

[tom66]

Re: Help with no backlight on Toshiba 42AV504D

Readings so far indicate fuse is blown

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

Tom66 know i shouldnt realy do it but jumped the fuse with a piece of speaker wire. still nothing.

[tom66]

Re: Help with no backlight on Toshiba 42AV504D

Did you check the voltages each end as Vince instructed above?

[Mikeyboy2007]

Re: Help with no backlight on Toshiba 42AV504D

yes tom both ways on both fuses are reading 24v