Quadro LCD 32KL21 backlight off after one second

[seki007ful]

First off all, sorry for my bad english. I have problem with that quadro LCD tv:
Motherboard: Vestel 17MB22-2
PSU: Vestel 17PW15-9
I now that is crappy tv but it work great until now.
Tv start normal and after second backlight turn off. In that second i can see everything on lcd, switch program or input on remote. So tv is working normal, i can hear sound and see the picture when turn strong flashlight in to panel but backlight wont work. When i turn off tv and on again everything is the same, one second of light and backlight turn off. Voltage on psu to inverter are good (i think) and i dont have any more ideas where to start. Before i open this thread i red apsolutly everything and still no progress. I replace all capacitor on psu including both 15n-630V and big 150uf-450V. Voltage remains the same as before. All five rails from psu to inverter are 24.3, dim(yelow) is 3.03V and BL ON(blue) is 3.7V. All voltages ar the same and tv work no mather is inverter cable plugged in psu or not. So, is this inverter problem, or ccfl`s ?? Or anything else ?? I dont want to purchase something wrong for that old tv so any help is welcome. Thanks.

[R_J]

Re: Quadro LCD 32KL21 backlight off after one second

Post a clear picture of the inverter board, I suspect the problem may be on it. Maybe bad transformer on inverter??

[seki007ful]

Re: Quadro LCD 32KL21 backlight off after one second

I will post picture later, dont have good quality camera right now, sorry. But on visual everything seems good to me and all ccfl`s work properly that second or two after start. Is there any way to power up backlight on external 24v power supply to see will it be any difference or inverter need BL ON and dimm voltage to power up properly? Or is there a chance for inverter to work if I remove one by one tube and test it that way?

[seki007ful]

Re: Quadro LCD 32KL21 backlight off after one second

O.K. friend, it seems like you been right. I test all of transformers on inverter with multimeter and find out that one of them no any resistance at all, no matter on what pin measuring. All others ar good and have the same values. I remove that broken transformer from board and test tv but results are the same as before, one second of light and than turn off complete backlight. Because I don't want to spend money on this old tv and darker area on screen without that lamp is barely noticeable, my next question is, is there any way to bypass security circuit on this inverter board to prevent board to shut down all other ccfl`s? Is there any way to bypass that transformer?
Once again, sorry for my bad english, i hope so that you understand me. Here is the picture of inverter, bad quality, taken with mobile, sorry.
Model: CPT 320WB02 Rev01 4H V1448.371/C1

[tom66]

Re: Quadro LCD 32KL21 backlight off after one second

Bypassing the circuit would do so for all bulbs and so would be unsafe (fire risk.) The transformers are available for about £5 each, if they are the DARFON type, very cheap imho.

[seki007ful]

Re: Quadro LCD 32KL21 backlight off after one second

Thanks Tom. Yes, I now its cheap but in my country parts for lcd`s is hard to find and I don't want order anything, wait for it half year and pay shipping before I was hundred percent sure that is the inverter fault and not psu or something else and because of that i'm interested in that bypass safety on inverter board just to be sure that tv will work properly if I replace that transformer.

[Th3_uN1Qu3]

Re: Quadro LCD 32KL21 backlight off after one second

It's not that difficult, from the UK or Germany the parts will be there in a couple weeks.

[seki007ful]

Re: Quadro LCD 32KL21 backlight off after one second

Please guys, I`m not ask how to buy elements, if somebody have experience with that inventer board and know how to bypass this let wrote it here, if you dont know please dont write how to order transformer or anything similar because I'm not retarded. Thanks to all anyway.