MODIS BackLight Repair

[arnoldtx]

Does anyone have a source for the capacitor?

[Witsend]

No more Radio Shack, maybe try Digikey

https://www.digikey.com/products/cap...saAoAFEALw_wcB

[Igore]

Where did you find the diagrams? I can't even find a diagram for a 10 year old Kenmore refrigerator control panel.

[AnalogueFan]

I'm not having a lot of luck finding a small quantity (2-3) of the LT1786FCS chip even remotely close to the bulk price ($5.95/ea minimum of 50) at, say, Analog Devices or Mouser. Anybody know where I can find this chip for way less than hundreds of dollars for a small quantity of these?

Also, here https://www.analog.com/en/products/l...ct-discussions are two different LT1786FCSes (scroll down near bottom)--can I use either one?

BMWGuy, great thread, many thanks. My EEMS300 display is useable but not very bright.

Originally Posted by BMWGUY

Hello, I have repaired many MODIS CCFL back lights. The LT1786FCS Ic that controls current to the florescent inverter and the primary winding capacitor are the problem 99% of the time.

The LT1786FCS receives info via the mother board SM bus.
It then increases or decreases the current to the inverter.

The SMDIC03680TB00KQ00 capacitor is on primary winding.
If it is bad you can only get 1/2 the KV output needed.

I always replace both at the same time.

Here is a link to buy the Ic http://www.linear.com/product/LT1786F

Here is a link to buy the capacitor http://www.mouser.com/ProductDetail/...IbFyINUMQIo%3d

[AnalogueFan]

BTW, just for general info, I got my capacitors at Mouser
https://www.mouser.com/ProductDetail/505-PPS28.1-63-10

Originally Posted by arnoldtx

Does anyone have a source for the capacitor?

[AnimeFunTV]

Got both from Mouser for under $25 with shipping.

I will say this though. After replacing both, my backlight didn't really change in brightness but now after about 5 minuets the backlight will die out. I'm not sure if its the CCFL tube or something wrong with the IC I got. I reflowed the LT1786FCS and the Cap and still no difference.

I did have to use pn SMDTC03100TA00KQ00
vs SMDIC03100TA00KQ00 (as its not available). The only difference between the two, is one is made out of Polyphenylene Sulfide (PPS) and the other is Polyethylene Terephthalate (PET), both are the same ratings and voltages.

So I am unsure what is causing the Backlight to die out, I did save the old LT1786FCS and plan on soldering it back on and see if possibly I got a defective new LT1786FCS. If the backlight dies again I need to see if possibly the CCFL tube is just bad and can't handle the voltage from the new parts? Dunno if my multimeter can read 1kV or more...