Panasonic TH-L32C30A Shut down 1 red blink

[dkneyle]

It tries to start up. I can see the backlights appear to fire up at least twice. After about 10 seconds it shuts down with a single red light blink code.

During the time that the backlights do come on the menu text does not look anywhere near as bright as I'd expect. I'm wondering if I have an inverter issue?

[tw2005]

Re: Panasonic TH-L32C30A Shut down 1 red blink

you'd have to check the manual but I suspect 1 blink is backlight SOS.

My experience with LCDs is huge. I've done 1 ! panasonic , baby 19", turned out to be a bad cap and blown HFETs for me.

[tw2005]

Re: Panasonic TH-L32C30A Shut down 1 red blink

Same model in NZ.

https://www.badcaps.net/forum/showthread.php?t=41550

having a quick read of that, what he has sounds like what I had with the 19" , continuous blinking and endless cycling of the TV trying to start the backlight.

[tw2005]

Re: Panasonic TH-L32C30A Shut down 1 red blink

training guide should be similar setup. check the H Fets underside of the board for short

[dkneyle]

Re: Panasonic TH-L32C30A Shut down 1 red blink

Well the single red blink certainly means "SOS Backlight". I checked the resistance values of the inverter transformers and they check out OK. I'll look at those FETs. Otherwise it might be suggesting blown fluoro tubes do you think? I'll have another look tomorrow and let you know.

[dkneyle]

Re: Panasonic TH-L32C30A Shut down 1 red blink

Checked out those FETs and they seem to be OK. Certainly not short anyway. For anyone reading this thread, the type number of those FETs is TPC8116 (very hard to read). I've attached the datasheet which shows the pinouts.

Those capacitors you mention are all Rubyicons in this set and physically look OK. I know what you said about yours looking OK, but I'll do a few more tests before pulling those caps out.

The inverter transformers all seem OK from a DC measurement. Next I'll fire it up with a small 6W fluro tube across each of the 4 inverter outputs and see if we have high voltage being generated. If so I think I'll have to assume a backlight problem and start stripping down the panel.

[tw2005]

Re: Panasonic TH-L32C30A Shut down 1 red blink

Checked out those FETs and they seem to be OK. Certainly not short anyway. For anyone reading this thread, the type number of those FETs is TPC8116 (very hard to read). I've attached the datasheet which shows the pinouts.

Those capacitors you mention are all Rubyicons in this set and physically look OK. I know what you said about yours looking OK, but I'll do a few more tests before pulling those caps out.

The inverter transformers all seem OK from a DC measurement. Next I'll fire it up with a small 6W fluro tube across each of the 4 inverter outputs and see if we have high voltage being generated. If so I think I'll have to assume a backlight problem and start stripping down the panel.

Yeah , with mine i suspect it was a rogue supply of caps they used. weirdest thing I've seen.

Well looks like you have a decent fault to track but inverter cct and CCFL are not me.

[dkneyle]

Re: Panasonic TH-L32C30A Shut down 1 red blink

Looking through the back I can confirm that the CCFLs appear to be working. This TV has four HV outputs to drive the CCFLs. I disconnected each in turn to confirm that the CCFLs in that section of the panel went black. So I'm reasonably confident that the CCFLs are OK. (Disconnecting inverter outputs did not in anyway change the cycling on-off pattern.)
The TV cycles three times before shutting down. The CCFLs come full on then drop back to about half intensity then shut off. As I say, this happens three times.
Any thoughts anyone?

[dkneyle]

Re: Panasonic TH-L32C30A Shut down 1 red blink

Measuring the secondaries of the inverter transformers shows that three coils read about 1270 ohms and the fourth reads about 100 ohms less (1170 ohms) open circuit. It doesn't change the behaviour of the set if I disconnect the output of that coil; it still cycles about three times before quitting.
(BTW, I did replace the two electros that TW2005 mentioned without any change of behaviour.)

[Ragga_NZ]

Re: Panasonic TH-L32C30A Shut down 1 red blink

Hi,

Did you manage to find out the cause, I have a similar problem with my TV same model.

Thanks

[dkneyle]

Re: Panasonic TH-L32C30A Shut down 1 red blink

I'm pretty sure it's a crook inverter transformer. I can't source just the tranny so I think I'll have to change the whole board. I've just been waiting to sell a few old boards to justify the cost of the replacement for this TV

[dkneyle]

Re: Panasonic TH-L32C30A Shut down 1 red blink

Diagnosis was correct I believe. A failed (shorted-turn) inverter transformer. In the end I imported a fairly cheap second-hand power supply board via a private E-bay seller. All fires up perfectly now. I hope this helps others in the future. Couldn't source just the transformer.