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Repairing a Flat screen tv (viore lc26v58)

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Enzy

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I am not a pro at electronics but I like to attempt fixing anything I can.

I got this TV to check from a friend at first there was no power, I pulled it and checked the power supply board had 7 visible bad capacitors on it, so I got the replacements and changed them and also changed 2 others that was close by, upon testing the other components like diodes and transistors I haven't found any to be bad. I assembled the tv and applied power and it has a double pole switch that I have to turn on first which send power to the power supply and the stand by light comes on, then it has a push button as another power button for the TV to turn on after pushing the push button the standby (red light) turns green but the screen doesn't turn on. On the connector that connects to the screen it should a 24v but when I test the voltage across it the most I get is 4.8 volts probably 5v the most as the voltage drops the longer its there until it goes to zero volts.

I Am now assuming the power supply is still at fault so I am trying to find the issue, so checking the ferrite core transformer which should be stepping down the voltage, I was doing a resistance test across the legs for the primary legs all legs give me a direct short even when the PCB doesn't connect them, and the same thing for the secondary legs all legs give a dead short, across the primary and secondary it doesn't short out though I get a high resistance like 8.3m ohms.


 

Before you move on to other things- I would check those capacitors again. Including the new ones. Remember we had a bad batch of capacitors a few yrs back, those could be out of that batch? you can look it up online- I can't right now otherwise I would for you. You say you believe its the power supply, but then mention the light comes on!

Just my two cents... as I went through a similar repair myself, and it was all due to capacitors... you can't tell with these by looking if they are bad...
 
Ok then I never had that kind of problem but I will try and replace them again to see if that was the issue.
 

I think it unlikely your new caps would be bad. It sounds like the 24V supply fires up then shuts down possibly due to the load further downstream. Did you check the board that the 24V supply feeds?
Power supplies can continue to run with bad caps so there could have been another problem initially like a short in the load.

Larry G
 

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