Toshiba 32AV502R Backlight comes on and goes off

[RobII]

Having trouble nailing down the issue on this. I'm pretty sure it's the inverter board but want to be sure. Voltages from the power supply to the inverter board are all good (24v, 5 and 3) and stable even after the backlight goes out. I can't find the service manual. Only thing I found was the SMART troubleshooting guide.

All backlights appear to turn on. Is there something else I can check on the inverter board to be sure there isn't any other issue?

Thank you!!

[budm]

Re: Toshiba 32AV502R Backlight comes on and goes off

Check the resistance of the HV secondary winding of the transformers to see if they are within 3% from each other or not.

[RobII]

Re: Toshiba 32AV502R Backlight comes on and goes off

Thank you budm! I want to make sure I am testing the right points for the secondary.

Check the resistance of the HV secondary winding of the transformers to see if they are within 3% from each other or not.

[RobII]

Re: Toshiba 32AV502R Backlight comes on and goes off

Bumping this up. Can someone confirm I'm testing the secondary coil at the right points? Thanks!!

[budm]

Re: Toshiba 32AV502R Backlight comes on and goes off

Looking at the traces layout, it looks like it has one secondary winding between the top left corner pin and bottom left corner pin, then another secondary winding at top right corner pin and the bottom right corner pin.
I cannot read P/N on the transformer to get the pin-out of the transformer.
Can you read the numbers on the top of the transformers?
http://www.shopjimmy.com/sharp-rdenc...t-inverter.htm

[RobII]

Re: Toshiba 32AV502R Backlight comes on and goes off

Sorry for the delay Budm. My curiosity go the best of me, I wanted to make sure all the lamps were coming on. I removed the LCD, and it is indeed a bad lamp!! I would like to replace them all if there is a reliable source.

Looking at the traces layout, it looks like it has one secondary winding between the top left corner pin and bottom left corner pin, then another secondary winding at top right corner pin and the bottom right corner pin.
I cannot read P/N on the transformer to get the pin-out of the transformer.
Can you read the numbers on the top of the transformers?
http://www.shopjimmy.com/sharp-rdenc...t-inverter.htm

[Andrew F. Ali]

Re: Toshiba 32AV502R Backlight comes on and goes off

If you can't get the CCFL to buy, perhaps you may consider converting this TV to LED backlights. You have 24Vdc. Can you determine if the BL-ON and Dim signals are present?

[R_J]

Re: Toshiba 32AV502R Backlight comes on and goes off

here is a link to a company that supplies ccfl's https://www.ccflwarehouse.com/lacclaforlcd.html
at $25.00 each I don't think it would be worth it. so you would need to look to a China supplier, or find a 32" toshiba with a broken screen and repace the bad ccfl.

[RobII]

Re: Toshiba 32AV502R Backlight comes on and goes off

Had't thought going that route. There is nothing on the PS or inverter that says BL-ON. I do see 3v for DIM and 5v for INV on the PS going to the inverter board. Both are present along with the 24v even after the lamps go out.

If you can't get the CCFL to buy, perhaps you may consider converting this TV to LED backlights. You have 24Vdc. Can you determine if the BL-ON and Dim signals are present?

[RobII]

Re: Toshiba 32AV502R Backlight comes on and goes off

Ouch, yeah $25 ea is steep to replace all. Might just get the one and flip the TV.

Thanks for the link!

here is a link to a company that supplies ccfl's https://www.ccflwarehouse.com/lacclaforlcd.html
at $25.00 each I don't think it would be worth it. so you would need to look to a China supplier, or find a 32" toshiba with a broken screen and repace the bad ccfl.

[R_J]

Re: Toshiba 32AV502R Backlight comes on and goes off

Check with a local repair shop, they might have a a panel with a cracked screen you could get a couple from.

[Dumah Brazorf]

Re: Toshiba 32AV502R Backlight comes on and goes off

I think you could buy them from aliexpress but you'll have to wait. They usually send them in a sturdy pvc pipe. I had for 15,19,22" screens, always arrived in good conditions.
I see yours have some type of connector.

[Andrew F. Ali]

Re: Toshiba 32AV502R Backlight comes on and goes off

Had't thought going that route. There is nothing on the PS or inverter that says BL-ON. I do see 3v for DIM and 5v for INV on the PS going to the inverter board. Both are present along with the 24v even after the lamps go out.

INV or INV-ON is the BL-ON signal and that is working as you have the 24 Vdc. I would suggest converting to LED. However, if you can get replacement CCFL that might be easier.........

[RobII]

Re: Toshiba 32AV502R Backlight comes on and goes off

Unfortunately there aren't many repair shops....hmmm, I can't think of any as a matter of fact. There is a local ecycling transfer station that accepts TV's etc. I spoke to the owner last year and told me I can have whatever I wanted as it helps him out. That's a crap shoot though. I've stopped over a couple of times throughout the year and it's mostly CRT's that get dumped.

Check with a local repair shop, they might have a a panel with a cracked screen you could get a couple from.

[RobII]

Re: Toshiba 32AV502R Backlight comes on and goes off

Ok, good info, thank you. Sounds like replacing with LED might be much more expensive too. I have a replacement tube on the way.

INV or INV-ON is the BL-ON signal and that is working as you have the 24 Vdc. I would suggest converting to LED. However, if you can get replacement CCFL that might be easier.........

[RobII]

Re: Toshiba 32AV502R Backlight comes on and goes off

Forgot to update. Received the new lamp from CCFLWarehouse. Side note, they package lamps SUPER SUPER well!! It had three layers of padding. Color me impressed. Only down side with the replacement lamp is the leads on either end were pretty thin gauge compared to the OEM lamp.

Happy to say, saved another TV from the landfill/ecycling bin.

Thanks to all that helped!

[Andrew F. Ali]

Re: Toshiba 32AV502R Backlight comes on and goes off

Good job!!!!