Emerson LF501EM4 DS4 no standby led

[videotronics]

faint chirp when menu button pressed

all3.3v pulsing to .5v on 2 seconds

disconnect ribbon to mainboard
all3.3v 3.3v

connect ribbon to mainboard
resistance all3.3 to ground 810 ohms

disconnect ribbon to mainboard
connect all3.3v to p-on_h2
p-on+21v 20.9v
amp+13v 12.5v

[CapLeaker]

Re: Emerson LF501EM4 DS4 no standby led

Well, sounds like the main board is dragging the psu down. What is the resistance on the main board from stby to gnd?

Search for your model number in badcaps. There is one thread not powering on. It has a schematic for your TV. There are a number of reasons why the main board could load the 3.3v rail down. One would be the little ir board, another one could be the zener diode on the tv module is short to gnd, etc...

[budm]

Re: Emerson LF501EM4 DS4 no standby led

You may have shorted cap on the main board.
Reconnect the cable between main board and power supply board then check the resistance between GND and p-on+21v, amp+13v 12.5v to see if any one of them shows low resistance reading, report the readings.
You may have the typical bad cap C3214, c3943.

[videotronics]

Re: Emerson LF501EM4 DS4 no standby led

connector on resistance to ground
P-ON+21v 26k ohms
AMP+13v 6.6 ohms
ALL3.3v 810 ohms
connector off resistance to ground
P-ON+21v 26k ohms
AMP+13v 1.75 Mohms
ALL3.3v 810 ohms

assuming overload on the AMP+13v supply looking at audio output IC3801 and peripheral electrolytic filter capacitors C3829 and C3831

[budm]

Re: Emerson LF501EM4 DS4 no standby led

Does your main board have C3214, c3943?
Please provide Pictures and P/N of your main board.