emerson lf501em4 turns on when plugged in then turns off

[h82loseejr]

hello i came across this tv and am trying to get it to work i plug it in it turns on and the splash screen comes up (it says emerson) and then it kinda clicks and shuts off as soon as the tv should be displaying i can see the channel box right before it shuts off iv looked at power supply and all caps look good although there is some white crusty stuff on the big one that is below the 2 smaller transformers toward the bottom of the board. i have unplugged the ldvs cable with no change just looking for the next place to go there is some discoloration on the powersupply board on the top left and top right (where it says "top side"

[paulstef]

Re: emerson lf501em4 turns on when plugged in then turns off

When the picture goes dark, is the backlight still on?

[h82loseejr]

Re: emerson lf501em4 turns on when plugged in then turns off

no the whole set shuts off which is why i am kind of at a loss on what to do nextbecause it all powers off if i hold the power button again it will come back on go through the splash screen again and then it shuts off when it does you hear a click and thump through the speakers

[paulstef]

Re: emerson lf501em4 turns on when plugged in then turns off

The discoloration may be normal, components that dissipate more heat will cause this.

We need to find out if the PSU turns off by itself or if it is commanded by the mainboard.

If nothing is indicated on the boards you will need to measure all signals on the white flat cable connecting mainboard and PSU when 1. in initial standby, 2. ON (screen on), 3. after it clicked and turned itself off. Post the results here.

[h82loseejr]

Re: emerson lf501em4 turns on when plugged in then turns off

ok so i can do that now i should not use chassis ground for my common correct? now if so how do i go about finding my common there is a wire (solid silver) coming out labled j187 gnd should i use that?

[paulstef]

Re: emerson lf501em4 turns on when plugged in then turns off

Usually the chassis is secondary ground. In order to use it as a reference point for measurements the PSU needs to be screwed to the chassis.

[h82loseejr]

Re: emerson lf501em4 turns on when plugged in then turns off

starting with the top pin as being pin #1 i will put 2 columns with left being off and right with bl on

1 ground
2 0 not common to ground and no volts on or off
3 0 off; .2 after pushing power button .1 when backlights come on and seems to flash .2 right before backlights go off and tv shuts off
4 2.9 ; 2.9
5 0; 3.0 as soon as push power
6 0; 3.2 as soon as push power
7 0 ; .1 after pushing power then jumps to 2.2 with backlights on split second before backlights go off and tv shuts off, i see 2.4

8 3.3; 3.3
9-13 ground
14 0; 0
15-18 6.3 off 12.4 on
19-22 11.4 off 21.2 on


i tested these with the lvds cable plugged in and also un plugged it makes no difference

[h82loseejr]

Re: emerson lf501em4 turns on when plugged in then turns off

im not really sure where to go from here

[h82loseejr]

Re: emerson lf501em4 turns on when plugged in then turns off

i couldnt find the service manual for this particular tv but this one is close and it looks like they have the same power supply


edit: i did find the correct one im not sure if i can take the other off but the correct one is the phillips