Jaeheon Shim
Hi! I'm Jaeheon Shim, a computer programmer and technology enthusiast. Here on Learn The Technology, I write about technology and the effect it is having on our modern world. I write about a broad range of topics, ranging from 3D Printing to Cybersecurity.

Fixing A Free TV: Part 1

Last week my the whole neighborhood had a huge garage sale. While we were looking around, my family found a 50 inch TV for a price of 0 cents (Meaning it was free). I thought we were really lucky that nobody had stolen it, but the TV came with a catch: It didn’t work. When I tried to turn the TV on, it would show no sign of life except for a flashing LED. But when I looked up the price of the TV – Which was a GT30 Series Panasonic Plasma TV – I quickly found that the television was worth around 1,500. I thought this was too good of an opportunity to pass up, and I was determined to fix the TV. If I do manage to fix the TV, I would currently make a profit of 1,500. (Unless I have to buy extra parts.)

The first thing I noticed about the TV was that the fans were not spinning and the backlight was off. The only thing that responded when I pressed the power button was the power led.

The LED indicator was the only thing active on the TV

I upon closer inspection, I realized that the led was actually blinking 7 times, stopping for about two seconds, then blinks 7 times again. I assume this is some kind of error code that the TV is trying to desperately signal to me.

I didn’t know what is wrong with it, so I proceeded by taking the TV apart carefully. You shouldn’t do this at home unless you know what you are doing because the capacitors inside the television can still be charged even when the TV is unplugged. The voltage on these capacitors is usually around 250 volts, so if you touch them, you will have a bad day. (Or you won’t have a day at all.) Most of these TV’s have a discharge resistor, but I wasn’t taking any chances and shorted out the capacitors with a screwdriver.

The first thing I realized when I opened the TV was that everything looked fine and I didn’t know what I was doing at that point. While I assumed that the big parts such as the capacitors would be blown or damaged, I couldn’t find any damage even through close inspection. This isn’t abnormal though; there was a good chance that either the parts were damaged in the inside, or some other part was damaged. There were a lot of heatsinks, and I didn’t want to go through the hassle of pulling off each and every one of them.

There were 5 boards inside the TV. The first one had the power cable connected to it, so I assumed that that board was responsible for power distribution. I checked the fuses on this board to make sure that they were not blown out, and they were not. The next board had all of the HDMI inputs and USB ports linked to it, making me pretty sure that that board dealt with all of the “smart” features of the TV. One thing I also noticed about this board was that there was an ethernet port soldered on it. That meant that if I manage to fix this TV, it could mean that I would have a decent TV to watch movies on. Unfortunately, I knew that if something was wrong with this board, there would be little chance that I would be able to fix the whole TV. But the good thing is, that board doesn’t really break easily unless you have a small child that constantly abuses your TV. And judging by the lack of dents and scratches on the TV, I concluded that that was not the case. Next, there was a board under the smart board(The last board I discussed.) Upon intense Googling, I learned that plasma TV’s such as this one have a board for each of the 2D axes, X and Y. This board was the Y-Sustain board, which is basically responsible for all of the vertical signals. This board works in conjunction with the X sustain board which, hence its name, controls the horizontal signals. Both boards create a grid which makes it possible to display images on the TV.

Finally, the last board on the TV are the Driver Board..s? Remember when I said that there were 5 boards? Well, there are actually 6. The last two boards are the upper and lower Y driver boards. This takes the signals coming from the Y sustain and displays them on the TV screen.

Now to figure out the problem. First, I need to find out which board is broken. So I thought, logically, if I disconnect each of the boards one by one and something different happens when I disconnect a specific board, there must be something going on with that board, right? So I disconnected all of the boards one by one. Upon disconnecting the Y-Sustain Board, I found that the TV now displayed 8 blinks instead of 7. That means that something is wrong with it…

So the first thing I did was check all the capacitors one by one. While I was fixing the TV, somebody stopped by and told me that the problem with most of these TV’s is that the capacitors always go out. So I probed the capacitors with my multimeter, and upon touching the first one, I realized that it was shorted. That wasn’t really the problem, but I didn’t know that and went ahead to desolder all of the capacitors on the board. But when I probed the connections again with my multimeter, they were still shorted! I was wrong!

Upon internet research, I found out that this board breaks often. In fact, it broke so often for customers that Panasonic had to prolong the warranty period for it. Even though my board is not under warranty anymore, I was pretty sure that this board was the problem.

[Sorry but I forgot to take pictures for this step! 🙁 ]

To be honest, I don’t think it would be worth it at this point to buy all of the broken components and replace them. That would take time and money. But I still really wanted to finish repairing this TV. So I bought the board on eBay, and it is set to arrive next week! So until then, there is nothing that I can do. But you could subscribe to my blog so you don’t miss out on updates to this project! So be sure to subscribe using the form at the bottom of my website, and until then, see you next time!

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7 Responses

  1. KYU NAM SHIM says:

    Good luck smart guy!

  2. C Metzger says:

    How much was the board on eBay?
    Looking forward to Part II!

    • Jaeheon Shim says:

      The board was not very cheap! Since Panasonic gave up on making plasma TV’s, I had to buy a used board on eBay. It cost $110, but if I do manage to fix this, it will be totally worth the price! And if I fail… well I can always refund the board. I don’t know why somebody has so many of these boards on hand though… you can buy one here: https://www.ebay.com/itm/163058980546?ul_noapp=true.

      Why don’t you consider subscribing to Learn The Technology so that you don’t miss part II? You can always unsubscribe, and I the only thing I send to you will be post notifications. Thanks for your interest!

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