Panasonic TH-L32C20CX

[T-con]

The problem with this tv is if left unpluged for several days, the tv will powerup normally for few minutes then suddenly it shuts itself off, trying it again to power the tv on it gives 4 blinking red light, what do you think is the problem?

[tom66]

Re: Panasonic TH-L32C20CX

4 blink is PSU, usually... So I'd check for cold solder joints and see what the main power rails do when set is turned on with 4 blinks.

[T-con]

Re: Panasonic TH-L32C20CX

I've resoldered some cold joints and tried replacing caps even if not bulged, still nothing, there's no voltage label on the psu board so i'm blind with power measurements, any ideas What to do?

[T-con]

Re: Panasonic TH-L32C20CX

Hi tom66,
i've searched your tv repair reference library but did not find my model, instead i found this model (TC-L32C22) that has same pics. Of the power board and A board, what do you think? Power blinking 4 times says the problem is DTV12V_SOS, would this mean i need to check the 12v power board rail? If the 12v from power board is ok, where should i check from A board?

Thanks in advance...

[selldoor]

Re: Panasonic TH-L32C20CX

Pictures are not clear enough for troubleshooting.
You should find the connector from the power supply to the main board and with it all connected up test each pin and list the results

pin1 5v
pin 2 0v
pin3 11.8v and so on.

When the set fails do the test again.

[T-con]

Re: Panasonic TH-L32C20CX

Will try that thanks selldoor

[T-con]

Re: Panasonic TH-L32C20CX

Here are the power measurements from power supply, pin 1-16, it is taken when the tv is powered on (blinking green light) before the set shuts off with 4 consecutive red light. Are these voltages correct?

Pin 1&2 - 5V
3. - ground
4&5 - 10V
6. - ground
7. - 15V
8. - ground
9. - 2.2V
10. - no contact
11. - 5V
12. - 2.2 V
13. - 0V
14. - 0V
15&16 - ground

[T-con]

Re: Panasonic TH-L32C20CX

Looking at the schematic of TC-L32C22 voltage reference of power board, my voltage readings maybe low, like the 12v reference i only get 10v, and 17v i get 15v, any idea where should i check? Thanks.

[tom66]

Re: Panasonic TH-L32C20CX

Sometimes, that is OK. But not always. When the outputs do not have much load on them, they can sag. Right now, I'd look for an A board schematic to see what's triggering the SOS. I don't have time to do this right now (too late), but can have a look tomorrow if you remember to "bump" this post. Once SOS source is located, you can see if that 10V is truly too low, or if it's OK.

[T-con]

Re: Panasonic TH-L32C20CX

I don't know where to look at from the schematic, can you point it for me? And thank you for your time.

[T-con]

Re: Panasonic TH-L32C20CX

Finally fixed, I found a corrosion on the A board at the back of the lvds cable, luckily that didn't cause too much problem, I cleaned it, and to my surprise it came on, didn't know where that corroded path was going, so I will know what the sos 4 blink, but never mind, I had too much time on this one, thank's to all that helped here!