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Vertical problem in panasonic old television

The problem is vertical section of the panasonic colour television model no-TC-20L3T.please tell me the value of the protection diode [d-449]the colour code is adopt in this diode ,first colour is orange then blue.

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Re: vertical problem in panasonic old television - Standard (CRT) Televisions

Just use zener diode 9v-12v.

Posted on Nov 03, 2007

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How do i fix Panasonic TC25P22R like saw tooth shaped tilting top moving left to right and slowly blanking down about 0.5 inch after Power ON. Please how to fix?

Sounds like pin cushion circuit fault. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience.

Jan 18, 2015 | Panasonic TC-25P22R 25" TV

1 Answer

Why I have a thin line across the screen in my TV model Panasonic TC 21. After replacing the vertical IC the horizontal line across the screen reduced to few inches and not as it was earlier. vertica

First, You should to replace by original part, then you should check the voltages on power supply, and check the voltage for vertical IC based on datasheet, also check the voltages on vertical section including yoke and last you should check the ESR capacitors on vertical section.

Oct 13, 2014 | Panasonic TC-21PM10RQ 21" TV

1 Answer

Circuit diagram TC-29P20B

Vertical scan output section circuit fault. Horizontal line problem. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" or "Magazine" will make surf easy Pull up older posts. Surf the site with patience.

Apr 29, 2014 | Panasonic TC-29P22R 29" TV

1 Answer

My Panasonic TC-21Z88RBN doesn’t displays the total picture vertically ,when the picture is display it like not in the center of the screen sum of it is disappear in the bottom


Your TVs vertical output section has the fault. You just open your TV after disconnecting it from the AC mains wall socket, and locate the vertical output section. This section uses an Ic marked as part [IC 401] on the board and its number is LA7840. Just look for any loose soderings around its components legs, and the solderings at the IC legs, which has 7 of them. The IC stated above will be screwed onto a heatsink to radiate heat out of it when it works.
If all soldering point are fine, come towards the IC legs and measure the voltages at each leg. The voltages must be
pin 1= Ground
pin 2= 12.6
pin 3= 24.7
pin 4= 4.4
pin 5= 4.4
pin 6= 24v [vcc]
pin 7= 1.8
All voltages stated above are DC voltages with respect to ground. If any of this voltage is missing, find out the reason for that. If all of them are noted abnormal, IC may be defective, and replace it.
[vcc] stands for main input voltage to the IC.
If you need any more assistance, feel free to contact me through Fixya. Ok.

Dec 07, 2010 | Panasonic TC-21Z88R 21" TV

1 Answer

Loss of vertical sweep

Your TVs vertical output Ic may be damaged. You just open your TV and locate the vertical section inside, usually panasonic uses Ic numbered [LA7837] which will be marked as part number IC451 on the circuit board. It is a 13 pin Ic, sometimes the number may be different in your TV, as Panasonic uses four types of LA series Ics in their sets. I think that you have some knowledge in the service field, so the complaint states only "loss of vertical sweep", and so I'm not going too deep into description. OK.

Nov 06, 2010 | Panasonic TC-21PM10RQ 21" TV

3 Answers

Pictures shrinks.. Panasonic TC-20LM Television

Shrinking picture is a voltage regulation problem in the switch mode power supply, Possibly a cap used in the feedback circuit. Or an over current condition on the B+. This is a very tech intense repair because there is no magic bullet. If it is shrinking on bright scenes then you can bet it is a regulation problem, bright scenes draw more current from the power supply causing this effect. I would not suspect the horiz output because the regulation for this circuit usually comes from the main switch mode power supply. One diagnostic is to monitor the B+ going to the horizontal output and see if it fluctuates. If so you can bet it is a cap or optical coupler in the switch mode circuit.

Oct 10, 2009 | Panasonic Standard (CRT) Televisions

3 Answers


My experiance is to not put money into a TV that is over ten years old. TVs stress out their electronic components worse than almost any other electronic product. After 10 years, there are so many parts that are ready to fail that your are probably wasting your money trying to get any more life out of it.
Another option is to wholesale replace the main board by sending it to Module Exchange at 972-298-1212, or PTS Electronics 800-844-7871
Be careful on buying a new one though. Often times, these new technology ones are much worse. Always Google the model number of the set you intend to buy and add the word 'repair' or 'complaint' to see if it is one of the many models that are customer service nightmares being produced by even the most reputable companies today.
Hope ya fix it!

Feb 21, 2008 | Standard (CRT) Televisions

2 Answers

Power tv model TC-20L3T

Can you read the colors on the original resistor?

Feb 04, 2008 | Standard (CRT) Televisions

1 Answer

Panasonic TV - no picture, but sound is ok



it is due to vertical section failure.

  • before you start any work reduce brightness to avoid crt burn.
  • please check some loose contact or loose connector.
  • check supply to vertical section
  • check parts in vertical output section
  • check vertical ic.
  • hope this will help.
  • good luck.

Oct 17, 2007 | Standard (CRT) Televisions

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