Hello. I have a Mitsubishi WS55511 rear projection TV. Recently the remote quit working, and no matter how many times I changed the batteries, it still wouldn't work. At the same time, the buttons on the front panel wouldn't work either. Only the Power and Device buttons worked, somewhat. The problem here is not the remote, but the front panel buttons, as I found out. One or more of the buttons has failed, and the processor does not get a chance to respond to any other button input.
I managed to find a solution somewhere, but I would post the troubleshooting and repair procedure here.
If your tv is under warranty, you will not be able to do this repair. It requires getting into the tv, and will void your warranty. If you have a repair techincian performing the work, these instructions might be helpfull especially if he wants you to purchase a new Signal PCB (Printed Circuit Board) for around $300!
First, you need to unplug your tv from the wall. This is very important. Next, remove the speaker grille cover gently and set it aside. You should now see a bunch of wires coming from underneath the screen and buttons. These also disappear behind a small wood panel board. You will need to remove the wood panel board to unplug the wires from the rest of the circuit. Untwist the wire tie and release the wires. Remove the small wood panel board, about 8-12 screws. Now, be carefull and keep your hands away from the electronic components. Unplug the two harnesses gently. Hold the sides with your thumb and index finger and squeez as you pull.
Now you have to plug the tv back into the wall. Since you have unplugged the Signal PCB, the LED light will not blink, so you have to time yourself. Wait about 70 seconds, and turn the tv on with the remote control. Your set should come on, and all functions should work from the remote.
You have successfully isolated the problem to the front panel buttons on the tv! If the tv does not power up from the remote, the problem is worse, and will require further testing. My problem was the buttons, so I didn't have to do further troubleshooting. Now comes the fun part!
Turn off and unplug your tv from the wall. You will have to remove the screen to get to the Signal PCB. Follow the instructions in your manual to remove the screen. On the WS55511 and similar models, remove the 6-8 black screws directly beneath and across the screen. You need two people to remove the screen to prevent breakage. Nudge the bottom part of the screen until it pops up. Do this on both sides. Lift straight up, and remove the screen slowly. Be sure the wires are unplugged before you pull the screen out!
With the front of the screen facing the wall, lean the screen against the wall. This gives you access to the Signal PCB. Take your multimeter, and test the buttons individually. For those who don't know, put your meter on the Resistance / Ohm setting, :bigsmile:
Look closely at the PCB. You will notice the white boxes with the function of the button written in white, i.e., "Power", "Ch Up", "Ch Down", "Enter" etc...
The two soldered connections inside each box are where the button is soldered to. Take your multimeter and check for resistance between each pair of soldered connections. Take your time, because the resistance might be less than 100 or greater than 600 ohms. A good button is where the meter shows "OL" (Open Line) or however your meter is set up to show this. If there is any reading on any button, you know that button has failed. Basically, when no-one is pushing the button in, there is no contact between the two connections, as should be the case. Make sure you check every button, because I had two buttons that had failed. You could have more. Write down the ones that are bad. Remove the Signal PCB gently (6 screws) and inspect the front of the PCB. See if you can find any bad / burnt resistors. If you do, you will need to find out the value and replace them. Use the part number on the PCB. Download the service manual from: <http://www.eserviceinfo.com/index.php?what=search2>. Type in the model and manufacturer. The parts are listed towards the end of the pdf file.
I got my replacement buttons from MCM Electronics. They are identified in this forum as a good supplier. Order part P-EVQ21005G, Original Panasonic Switch. In the picture, it would be green instead of black. Not to worry, its just a color, and functions the same. I paid 81 cents each for these. Get yourself 10 for future failures. Can't beat the price! Or, you can find them at radio-shack or an electronics supply shop.
Anyhow, once you have the switch, you can remove the faulty switch(s) and solder the new ones in place. Make sure to solder them flush with the board and cut the leads after you have soldered the connections.
If you're comfortable, carefully clean the three projection bulbs inside the TV set with a lint-free cloth. Do this gently, and with a DRY lint-free cloth.
Now, put everything back together, plug the tv in and see if your repair worked! If it did, pat yourself on the back because you saved yourself a lot of money on a service call.:yay:
Follow these directions at your own risk. Before you attempt any of this, you should be somewhat familiar with soldering stuff and recognize that electricity cannot be seen, but it WILL be felt! Never attempt any repair with the equipment plugged in.
With that note, good luck and happy DIYing!!