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Samsung F2380 - Backlight still turning off after changing inverter

Hallo!

I have the common problem, where the backlight of the PC monitor is turning off, after setting the brightness above a certain value. Mine was around 65. The monitor just turns off the lights and I have to press the power button to turn it off and on again.


After opening the case, I saw that one resistor was burnt and I changed it. The monitor then, didn’t turn off even after setting it to 100 brightness BUT the inverter started burning and fuming. So I bought another inverter and replaced it. The monitor now turns off again after setting it to 65-70 brightness.

What exactly is going on here? The monitor also seems to be a little brighter on the right side of the screen.

Update (11/09/2019)

Hello @oldturkey03! These are the pictures!

This picture shows the top view onto the power board (?). It has the new resistor and the new inverter.

The inverter was a TM-07165 before and now is the TM-10160.

The new invertes’s resistances are 980 ohm and 984 ohm on secondary and 0.03 ohm on primary. Measuring the resistances of my old one are the same (except for the one side that has the burnt coils.. thats dead).

The resistor R301 is a 386kOhm 0.5W (not sure if enough watts) resistor I got from other threads on the internet. The old resistor was not distinguishable.

https://imgur.com/a/WmArn55

Edit: My soldering is not the best right now, because I was scared messing up with the other soldering points around the small double pins of the inverter. Will correct that

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@mike8 post some good images of what your screen shows. Then post some images of the inverter you replaced and what resistor and where you changed it. This could be an issue with the power board as well as the backlight array. You need to measure some of the output voltages to your backlight etc. Adding images to an existing question

Update (11/09/2019)

@mike8 now I understand what you meant by inverter. You replaced the inverter transformer (the inverter circuit etc. is actually part of the power board) I get a little lost with your ohm reading. What is the resistance between pins 2 and 4 and between pins 6 and 8? There are most likely other reasons why the resistor had failed as well.Check your diodes around D107 etc. Those are very glossy which could be a sign of excessive heat as well.

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Hello @oldturkey03 , this is the scheme: https://imgur.com/a/oe2z8fM keep in mind that i have the TM-10160 which has 984Ohms on secondary and 0.3Ohm on primary. The picture is just to show the pins/connections. I measure 984ohms between 5 and 6 and 983ohms between 7 and 8. The primary between 2-3 i get 0.3.

I de-soldered one of the diodes that were shiny and measured 212 with the DMM on diode mode. I resoldered the diode to the board and measured it again. It showed me a different value. The other diodes gave me the same value, so i guess they are ok. If i measure them the other way around the value rises constantly.

The board is a bit darker on the place where the diodes D106 D105 D104 are.. could those be damaged? they are all giving the same value if i have the DMM on diode mode and give a reading only to one side (the other way around the value is constantly rising).

When desoldered, they show me one value in the main direction and no value in the backwards direction, so I guess they are good.

I also checked the fuse (last picture) far left, above the two yellow caps, and it beeps on continuity test, so that seems good too

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