Emerson Funai LF391EM4 No Video

[neilc6]

This TV turns on with backlight but no video. There is low squealing/chattering coming from the power supply (may or may not be related). It has no tcon and its functions are integrated on the panel. With LVDS cable disconnected, it still squeals.

Fuse by LVDS connector measures good and 12V on both sides. Random checking of a few of the surface mount caps shows no shorts.

Main board is getting both +21V and +12V

Looks like it may not be salvageable.

[neilc6]

Re: Emerson Funai LF391EM4 No Video

Checked all the caps on the panel boards and none were shorted.

Found this shopjimmy repair kit for the main board. Has 1 capacitor, 1 diode, 2 transistors and 6 IC's and fixes "no video/picture, TV makes chirp/squeal sound" My board chirps when power is first applied.

https://www.shopjimmy.com/emerson-a3...r-lf391em4.htm

There are quite a few main board variations for this model. I did check the 6 regulators on the main board and all had stable (with a multimeter) voltages and no shorts at the input or output.

[neilc6]

Re: Emerson Funai LF391EM4 No Video

Searching Emerson on this board shows lots of thread and lots of power supply failures but none for my exact issue.

With the main board disconnected, there is still a quick chirp once power is applied. Humming only occurs with the backlights on.

I have taken off all the 4.7uF chip caps off the main board but it was the same so put them back.

I suspect the humming is a power supply issue on the led driver circuit of the power supply board and the no video may be a separate issue on the main board or panel boards.

[R_J]

Re: Emerson Funai LF391EM4 No Video

Does the power button actually turn the tv on and off, or does the tv just turn on when plugged in?

[neilc6]

Re: Emerson Funai LF391EM4 No Video

Tv turns on and off with backlight and humming but no video.

[R_J]

Re: Emerson Funai LF391EM4 No Video

It seems like you have a problem with the video processor on the main board, Have you checked if there is audio? usually a hdmi source will automatically switch to the right input. This is where a scope would tell you if there is video on the lvds cable or not.
There may be a slight problem with the power supply but I doubt it is causing no video.

[neilc6]

Re: Emerson Funai LF391EM4 No Video

Couldn't get audio out but not too sure without being able to see the screen. I have encountered this model before so will hold on to it for awhile to see if I get another one in to do some board swapping. One of the ICs in that shopjimmy repair kit is the main processor.