Emerson LF501EM4F

[OldEE]

My first post (besides the mandatory introduction).

I have an Emerson LF501EM4F, found it curbside for free. No remote. Ebay has lots of those. Would rather not buy one until I know I can use it.

TV is nothing but black screen. Flasing red power LED is only sign of life. Pressing buttons on back has no effect. LED flashes when you plug it in, never stops. TV never comes on. No backlight, no audio, no apparent video even with bright flashlight illumination. TV draws only 5 watts (140 shy of normal as stated on back of set).


Made by Funai:


Power supply board S/N:



Main board:


Keypad:


IR sensor board (Not photographed yet) has S/N BA3AU0G0203 1 __1.

Haven't taken the TV apart enough to see LED strips or LED driver board yet

I found the service manual by searching this forum. Thanks! Digesting...

A couple of other threads here about problems with this TV. I gather it's a bit of a POS. I tried some of the other suggestions but as yet have not made any progress. I would like to get it working.

I have decades of EE experience. I can solder professionally. I come from the days of vacuum tubes and discrete transistors though. Recently did some SMD work without issues other than a lot of cursing. Feel like I can tackle this. Worth a try, maybe?

Where should I start?

[budm]

Re: Emerson LF501EM4F

Start by checking Voltages on that power supply board, at least the standby power supply is working.

[dskall]

Re: Emerson LF501EM4F

Need voltages from connector that goes from power supply board to main board. Will need pin#- PIN DESCRIPTION -Pin voltage in standby-Pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - Pin Description - Pin Voltage standby - Pin voltage power on
1 - XXXXXXX - XXv - XXXv
2 - XXXXXXX - XXXv - XXXv
3 - XXXXXXX - XXXv - XXXv
4 - etc.

[OldEE]

Re: Emerson LF501EM4F

Will do. Measurements to follow today.

A few more photos to get us up to speed.

Back has a removable cover just over the boards. That's removed. Entire back could come off if LED or LCD panels need to be investigated.


PS board and main board, connected by one ribbon cable. Top cable on main board appears to be LCD driver. Bottom-left cable on main board goes to IR sensor board. Bottom right wires are speakers. Left wires on PS board I assume are LED strip supply. Bottom center cable on PS board is AC120V mains supply. Control buttons are wired directly to IR sensor board.



Closeup of cable attaching to main board.


Super closeup of pins on mainboard. Will measure here.


High resolution shot of PS board. No capacitors appear vented. no obvious heat failures or burn marks.


Voltage measurements and pin IDs to follow.

Thanks.

[dskall]

Re: Emerson LF501EM4F

You can upload pictures through go advanced/manage attechments

[OldEE]

Re: Emerson LF501EM4F

Ok will do from now on.

[OldEE]

Re: Emerson LF501EM4F

Measurements:



Also attached, note from service manual confirms my set is TYPE B, given the DS2 serial number. I'm currently using off-grid solar and my inverter is a little high, as shown in the Kill-a-Watt. I'm thinking the Power Supply board is ok. I guess these TVs jump into self-protection mode at the drop of a hat, if that's what it's doing.

What to do next?

Thanks.

[budm]

Re: Emerson LF501EM4F

It looks like your meter battery may be low because the readings are showing higher thane normal, I.E. 3.3V shows 4.14V.

[OldEE]

Re: Emerson LF501EM4F

It looks like your meter battery may be low because the readings are showing higher thane normal, I.E. 3.3V shows 4.14V.

You are correct. Batteryless analog meter has 3.3V, 12.7V and 21.2V readings dead on.

Protect3, Backlight-SW, and Backlight-ADJ are drastically low. The remaining readings are within reason.

[OldEE]

Re: Emerson LF501EM4F

The 12 and 21V supplies momentarily dip 10% when the red power LED blinks off (but not for the entire duration of the off cycle), as though something is trying to boot up. The 3.3V line does not dip.

The digital meter has the little battery icon displaying -- I guess that should have been a clue. I thought perhaps my 129V mains was the cause of high readings. Not so.

I tried it when I found it on city power. Same behavior then. My inverter sine wave isn't perfect here but it doesn't seem to affect computers or other LCD monitors. Am assuming it's OK for this TV too.

[RJARRRPCGP]

Re: Emerson LF501EM4F

Not so.

If you keep getting 129 V, then expect a bad neutral connection... Let me guess: around 125 V with no big appliances on
and then with one major appliance on, it jumps to 129 V and then 132 V or the like with 2 major appliances on, when reading from the leg that's not under high load...

[OldEE]

Re: Emerson LF501EM4F

No, just using a cheap inverter that's not very accurate. Not 3-phase, so no other leg. Saving up for a whole-house unit when I get more solar panels put up. It's an evolving project.

Back to the TV...

[RJARRRPCGP]

Re: Emerson LF501EM4F

No, just using a cheap inverter that's not very accurate. Not 3-phase, so no other leg. Saving up for a whole-house unit when I get more solar panels put up. It's an evolving project.

Back to the TV...

Cool. Did you see my 2016 posts of the crappy neutral at 285 Clinton St. in Springfield, Vermont?

[jackfish]

Re: Emerson LF501EM4F

check out capwizard thread.......https://www.badcaps.net/forum/showth...ight=LF501EM4F

[OldEE]

Re: Emerson LF501EM4F

check out capwizard thread.......https://www.badcaps.net/forum/showth...ight=LF501EM4F

There are 5 or 6 threads about this TV here.

The one with 111 replies was the most thorough. I read them all before joining and starting my own thread (and finding the service manual). Now that I am getting more acquainted with the set I will read them all again.

Apparently I need to jumper high the protect lines and backlight lines to fool the PS board into thinking the fault is not there, and then try to find the fault by observing how the TV behaves. Just want to make sure I know how to do that safely...