Help! My 51MP392H/17 suddenly will not work. When powered on, it goes into a constant cycle of powering on for 5 seconds then turning off and coming right back on. The only way to break the cycle is to unplug it. I can't get to any menu or see a picture. A little background. I replaced the amplifier modules about 6 months ago with no problem. I was getting a blue glow and decided to try replacing the coolant. Took out the Blue CRT and then decided that the coolant was ok. Put the Blue CRT back in and the TV powered up fine. Decided to see if the Service mode convergence menu might help. Got into that, it looked complicated and didn't make any changes. Powered off the TV (to get out of SGM mode) and it started doing power on/off infinite cycle. Any clue as to what might be going on??? Any help will be most appreciated.
"doing power on/off infinite cycle"
That is called protection.
When an internal fault is detected the TV goes on protect mode, that is a special diagnostic mode.
When in this state the TV will stay in standby, and it will be prevented from start by a device called protection switch.
The switch is the clicking noise that you can hear often when tv is on protection.
When that happens it means that there is an internal problem, as a bad voltage, a faulty component, a short , etc.
The TV is prevented from starting to avoid further damage, that is the reason why this is called protection.
Sometimes, and onlly sometimes, if you are lucky enough you can spot a bulged or chipped capacitor or resistor, or a broken solder joint on one of the boards.
More often you do not see anyting at sight, and you need to test the onboard components following the troubleshooting diagrams on the service manual.
Here is a multipart download for the service manual.
Otherwise you can purchase manual and parts here.
This is because it is detecting short down conditions somewhere within the set.
The symptoms you describe could be of several different causes. I am going give an educated guess it will be found the high voltage generator has failed. The cost of repair is always over $300.
In any event, the condition is convergent enough that you will definetly need a tech to take measurements and study waveforms in order to asses the exact cause and repairs needed.
There may be a loss of fluids in the projection tubes as well.
Have you checked the front control board panel for warped platic buttons that are continuisly pushing on the power button?
try disconnecting the control board panel and cleaning it and make sure that the plastic buttons are not pushing on the contact button , then plug the control board back in and see if that does the trick
electech
Try leaving the power off for about an hour making sure the plug is removed from the wall so it can reset itself
hope this helps
regards
Any of the capacitor on the main board is got loosed a minute soldering is required to thast capacitor.
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I looked and didn't see any capacitors that were obviously broken or out of place. Would it be only on the main board? There are three seperate circuit boards on this TV. Is one considered the "main board"?
What is a good method to identify a bad or "loosed" capacitor?
Thank you for the explanation Ginko. That makes perfect sense as to what is happening. Thank you for the link to the Service Manual too. I'm hoping that the troubleshooting diagrams will help isolate which board is causing the problem. That would make it much easier figure out what is causing the problem...
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