My Toshiba 43LF621U19 is not powering on
My Toshiba 43LF621U19 is not turning on. The blue standby light that used to glow when plugged in is not turning on.
I tested the power board and the main board to the best of my knowledge and they seem to be working fine. I was able to read in 5V for the standby voltage. The power going in to my standby light board is ~3V. There is one connection from the powerboard to my main board and another that is labelled as 1. VLED+, 2. NC, 3. NC, 4. NC 5. VLED-. When the powerboard is ON, I tested the voltage difference between VLED+ and VLED-. It is close to 0V (~0.43), and doesn't change when I press the power button on the TV. Is this expected? If so, what else might be going on and any ideas on how I can fix this?
Thanks in advance.
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Update 04/17/2022
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Vittal Premachandran VLED+ and VLED- are your backlight Anode and Cathode. The voltage will only increase if the main board "tells" your TV's power board to turn it on. Check the BKL voltage on your main board. Let us know what that shows you.
Toshiba is an extremely secretive and paranoid company. Service manuals and schematics are hard to obtain.
Do you have all the other 12V and 5V voltages coming from your power board/main board connector?
We need a clearer picture of your main board as well as the T-con board (blue board). Do you have power on the T-con board. check the F1 fuse for 12V
por oldturkey03
@oldturkey03 Thanks for your suggestions. So, if I do not detect any change in VLED voltage, then the problem could either be in the main board, or in the power board, right?
"Check the BKL voltage on your main board. Let us know what that shows you." - Sorry, but what is BKL voltage and how do I check it?
"Do you have all the other 12V and 5V voltages coming from your power board/main board connector?" - Yes. I am able to read the correct voltage from each pin that is labelled with 12V or 5V or 16V, both on the main board side and the power board side.
I uploaded other pictures of my T-con board and main board. Let me know if you need me to split them up into parts to help zoom into the components more effectively.
"Do you have power on the T-con board. check the F1 fuse for 12V" - I saw a tiny component labelled F101, which looks like a miniature fuse. I tested it and it seems to be open when unplugged. How can I test it for 12V? Btw, the board is labelled with 32V.
por Vittal Premachandran
@Vittal Premachandran F101 sounds right. Hard to see with my old eyes. If the fuse is open then it is most likely your T-con board. wht happens when you unplug it and try to start your TV? I'll see if there is anyway that we can start the power supply with a pull down or pull up resistor. Let's see what I can get on this Toshiba
por oldturkey03
Sorry, I might have used the wrong vocabulary. When I tested the fuse (F101) for connectivity, I got a beep on my multimeter. That means that the two end points are connected and the fuse is working fine, right?
I unplugged the tcon board and tried starting the TV. No luck. Standby light doesn't turn on.
por Vittal Premachandran
@Vittal Premachandran Oh okay. Yes you fuse has continuity and it is good. Still looking for Toshiba stuff :-)
por oldturkey03
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