TV repair help

[Javier]

Hello friends, God bless you!.. First excuse me for my english if you read any wrong word or expression, I am from Venezuela.
I have a LCD panasonic TV model TC-L32X1 which turns off after about 5 or 10 seconds . First the image is gone and then the sound disappears few seconds later. The red LED stays blinking permanently . I was reading about the blinking code of the red LED in panasonic TVs and the failure can be found according to the number of blinkings of the red LED.. In my case the red LED does not stop blinking for this reason I am confused because the manual does not explain anything about it.
I have checked all the resistors, diodes, caps and transistors in the power supply and they are ok. What else must I do? Thanks for your help

 

[shrtrnd]

Hopefully, somebody with some experience on your model TV will add information here later.
My opinion (and it's only an opinion with the information you've supplied), is that you have a problem in
your power supply, even though you haven't found a problem with it yet.
If you haven't already. I'd try to find a free on-line schematic of your model TV. It will help you isolate the problem.

 

[Javier]

Thanks you shr. Then you say the failure may be in the power supply. There is a terminal connector from the power supply to the main board with three voltages: 17vdc, 13vdc and 5vdc when the TV is on. When the TV turns off then 17 and 13vdc are gone but 5 vdc stays..

 

[Javier]

I would like to repair this TV because in this country, it is very to get electronic parts (specially entire boards for this kind of TV).

 

[davenn]

I would like to repair this TV because in this country, it is very to get electronic parts (specially entire boards for this kind of TV).

have you googled for service info yet as suggested by shrtrnd ?

 

[Javier]

The service manual can be downloaded from electrotanya but this does not show any schematic of the power supply. Today I turned on the TV and it worked ok with perfect image and sound and it worked over an hour and then it turned off.. I was looking for info in google but I have not gotten anything to help me

 

[shrtrnd]

It is difficult to troubleshoot this problem for us, because we tend to check things when troubleshooting that we take for granted and don't think about suggesting to you. My experience in troubleshooting this type of problem in similar TV's I've worked on, would be to suspect the small/medium-sized capacitors in the power supply section. I've found many times that the rectangular square caps often fail, causing similar symptoms. They're relatively inexpensive and easily replaced. Rarely do they show signs of physical stress failure, they just do.
Good luck with your troubleshooting of this problem.

 

[Javier]

Thanks Shr, the capacitors can cause this kind of problem. When the TV has not been turned on for several days then I turn it on and it works ok over an hour but when it turns off then it stays on a few seconds when turning it on. The electrolytic caps should be replaced and I will measure the high voltaje caps with the capacimeter. Thanks Shr for your help

 

[shrtrnd]

Don't just check the electrolytics. The box-type caps are some type of polyester that are prone to failure too.

 

[Javier]

Yes, shr, you are right, I have a special capacitor I have built to measure the polyester caps and other kind of non-electrolytic caps.

 

[Javier]

Excuse me I meant "capacitor meter"

 

[Javier]

Hi Shr.. Tomorrow I will test all the polyester caps. Shr and rest of the community, if I find nothing bad in the power supply and being sure that the inverter circuit is ok, what would happen if I bypass the protection circuit?

 

[shrtrnd]

Besides destroying the power supply, possibly a fire.

 

[Javier]

I checked all the non electrolytic caps and all of them are ok. Only I found an optocoupler with open circuit in the phototransistor. It may be the cause of the damage

 

[Javier]

Hi shr and rest of the forum. I think I gonna give up. It is very difficult to repair a TV like this if you have no any schematic to guide you. I think the only web site is electrotanya but this service manual shows neither the power supply nor the main board. I wanted to repair it but it would be with God's hand.

 

[shrtrnd]

You did what you could with the most common failures. The set has deeper problems. The problem with that is manufacturers change models so often, that it's often difficult to find specific parts for previous models. I think they
make them these days to run for a few years and then be thrown away so you'll buy the newest model. I commend you for attempting repair, most people don't have the initiative for that these days.

 

[Javier]

Thank youy shr.. I thank you anyway because somehow you helped me. Thank you and God bless you