howie
Junior Member
Posts: 88 
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Post by howie on Oct 24, 2017 17:49:27 GMT -5
Why me??? Looks normal like it's on standby with the red standby led on However, it is unresponsive from remote or buttons on the set.
Took it off the wall last night Tonight I flipped it over on the bed and removed the cover. Plugged it in and the friggin thing came on WTF.
Tried it many times. Gave up and put the cover back on and NO GO. Pulled the cover off again but this time still no go. When all is normal there is a tiny led on the main board that comes on. When unresponsive, no led. Was thinking the main board until I grabbed a meter and probed the supply from the power board to the main board there is 2 5.2 volt pins showing 5.14 volts. There is also a 12 volt pin that now is dead along with a 20 volt pin that is also dead. Wondering if it sat long enough unplugged and cooled off and that's why it fired up when I tried it tonight.
On a hunch, I just stuck the board in the fridge to cool it off. Lets see what happens next. If cool doesn't do it then heat. Seen weak caps respond to heating them up.
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Post by mastertech on Oct 24, 2017 21:11:38 GMT -5
Hey stranger. How are things going?  You wont have the 12v and 24v supplies if the main is not turning on the power supply. You can jump the power supply to turn it on and see if those 2 voltage come up. You can then jump the inverter on and see if the back light turns on and then make sure there is not an error signal going to the main and turning the PS off. Just remember the inverters put out around 1200v. You can also unplug the TCON and see if the unit comes on. |
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howie
Junior Member
Posts: 88
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Post by howie on Oct 27, 2017 23:14:10 GMT -5
SOS DD Hows things with you?
Do I leave P201 connected and jump out the 2 pins for power on (left to right)using a paper clip or something to probe the plug? Same for calling on the inverter TCON???
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Post by mastertech on Oct 28, 2017 9:10:48 GMT -5
Disconnect the harness from the PS to the main at the main end. Use 100ohm resistor to jump and you can use the harness connector to insert the resistor wires.
Assuming you have the +5v standby voltage, jump pins 2 and 8 with the 100 ohm resistor. Unplug tv while inserting resistor then plug in and test for +12v and +24v.
If you have good 12 and 24 volts then unplug tv and add another 100 ohm resistor between pins 10 and 20 and plug in tv and see if the backlights come on. Be careful now around PS since the inverters put out around 1200v.
If they come on fine then remove resistors, plug harness back in and remove harness to TCON and see if tv turns on and stays on with no picture but with backlights.. If it does not then problem is "most likely" the main. However on some tv's they will not turn on with TCON disconnected. Hence the "most likely".
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howie
Junior Member
Posts: 88
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Post by howie on Oct 28, 2017 11:35:59 GMT -5
Pins are not numbered on the plug side of the board on the ps or main I'll pull the main and see if they are numbered on the back. Had to go digging for 100 ohm resistors. Forgot where I put my selection of electronics goodies.
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Post by mastertech on Oct 28, 2017 14:17:58 GMT -5
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howie
Junior Member
Posts: 88
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Post by howie on Oct 28, 2017 16:05:54 GMT -5
All voltage there and the back light on. Power supply OK and the main boat bad???
For a test, how long should I leave it jumped out and the back lights on? It's been on for about 5 minutes now.
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howie
Junior Member
Posts: 88
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Post by howie on Oct 28, 2017 16:31:06 GMT -5
IC100 or IC1100???
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Post by mastertech on Oct 28, 2017 17:06:18 GMT -5
All voltage there and the back light on. Power supply OK and the main boat bad??? For a test, how long should I leave it jumped out and the back lights on? It's been on for about 5 minutes now. yeah, power supply looks ok. |
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Post by mastertech on Oct 28, 2017 17:24:41 GMT -5
Lets start here. Locate this ic and test voltages. Tv does not have to be turned on. Just plugged in. This is on the main board.  |
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howie
Junior Member
Posts: 88
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Post by howie on Oct 28, 2017 19:14:26 GMT -5
Found the IC on the bottom. Plugged everything in but the ribbon cables to the panel and flipped it over on a cloth to check voltage. Plugged it in and the sucker powered up. Shut it back off, flipped it back over and plugged the ribbon cables back in. Plugged it back in and it fired back up normally. It's standing up in a corner plugged in and running for now.
There was a bunch of used main boards and one new one on fleabay
Thought it was dead again. Turned around and saw it was off. No source connected. I think it timed out and shut off because I pushed the power button and it came right back on
Nope dead again. Back light shut off. When in standby the LED on the front is red When the set is on the LED turns blue. The back light turned off but the status LED was still blue but the set would not respond to button presses. And I swear I heard a distinct tic when the back light turned off
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Post by mastertech on Oct 28, 2017 19:42:52 GMT -5
Sounds like you may have a bad solder joint, a voltage off enough to be border line or a bad cap. Maybe get out that ESR meter and start checking caps on the main.
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howie
Junior Member
Posts: 88
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Post by howie on Oct 29, 2017 7:06:33 GMT -5
Pulled the board back out for closer inspection While doing that, jumped out the ps again including calling on the back lights and leaving it running. Retested ps voltages. The pin 4 and 5 5.2V measure 5.14 each and rock steady. 12V measures 12.07 and rock steady. the 20V pin registers 19.41 and is rock steady. This is with the plug P700 jumped with 100 ohm resistors and P201 back probed and monitoring each one while running.
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howie
Junior Member
Posts: 88
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Post by howie on Oct 29, 2017 7:30:24 GMT -5
Not a big fan of in circuit cap testing. Using my Peak ESR+ ESR70 most caps actually tested way high. That said, these came back reistering low or leaky in circuit
C163 330 uf
C165 330 uf
C603 10 uf
C600 10 uf
C1019 100 uf
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howie
Junior Member
Posts: 88
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Post by howie on Oct 29, 2017 7:41:38 GMT -5
FYI power supply has been jumped out with back lights on for about a hour and the supply voltages have not changed.
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