Jump to Main Content
Content > Home Theater > Repair Emerson LF391EM4F LED TV - Steady Red Standby Light
Repair Emerson LF391EM4F LED TV - Steady Red Standby Light

How I diagnosed and fixed my Emerson LF391EM4F LED TV for $40.

The Story

How I diagnosed and fixed my Emerson LF391EM4F LED TV for $40. It died in October 2015 about 13 months after I'd purchased this refurbished (3-month warranty) unit. This seemingly occurred after a power outage (or two). Yes, it's plugged into a surge protector as was everything else attached to the TV - except for the coax cable from my cable company.

Symptomatic Description

The unit powers on with a steady red standby light. However, I could not turn the unit on using either the remote or mechanical buttons. The red light never flashes, remaining steady.

For a couple of days after the power surges, if I unplugged the unit for a minute or so - to reset it - and then plug it back in, it would work; both the remote and the mechanical buttons would turn the TV on and off - until the next day. This worked for 2 maybe 3 days, but then the unit stopped responding to either input. Based on forum posts, I even left it unplugged overnight, tried the 60sec mechanical on button hold (while plugging in - and continue holding after). No changes in symptoms.

So I hit the web and started reading how to fix LED TVs. It probably wasn't worth paying someone else to fix this bargain brand unit. With my background, I felt I should be able to fix it. This included several hours of research, reading forums, blogs and watching YouTube videos. None truly specific to my unit and particular situation.


I still get a solid red standby light - even with the LED power and T-Con cables disconnected.

A visual inspection of the power board shows no capacitor bloating problems and everything else looks clean and solid everywhere. I do get power off the board but have not checked all diodes and such. However, the standby light supposedly suggests the power board is working fine.

I finally found a service manual listing the unit as made by Funai as both Emerson LF391EM4 and Magnavox 39ME313V/F7. That helped some on the searching as well as truly being able to service the unit - even if mine was a little later model LF391EM4F.

I first thought (hoped?) it was the IR/Buttons board based on reading posts on the web. Some other posts suggested it was that or the Main Board. But I found no definitive info on this particular model, nor for my specific situation. So I posted to DIYforums my Emerson LF391EM4F - Steady Red Light diagnostics and diagnosis - and was then told it was most likely the Main Board (thanks to my10cents).

I was disappointed to hear that because it was much more expensive, but I confirmed that diagnosis using the diagnostics flowchart (Video Signal Section, Flow Chart No. 1) in the service manual - the voltage does decrease on Pin(6) on the CN4052 connector on the Main Board when the Power button is depressed on the IR/Function CBA Unit which suggests it's the Main Board and NOT the Function CBA Unit (aka IR sensor board).

After searching for 2 days, I found one - for what I considered affordable - from ElectroParts, found via eBay ($40). It arrived fairly quickly, and I installed it. Voila! It was indeed the correct part that made things work again. I'll note ElectroParts offers 50% off your first order, and 5% off every other order (the codes are posted on their website).

Part Numbers and Other Information

Emerson LF391EM4F (refurbished)
S/N ME1******** (A3ATKUT) (label placed over the original 2EMH00264)
Similar Models: Emerson LF391EM4, Magnavox 39ME313V/F7
Manufacturer: Funai

Two Types (according to Service Manaual): A or B (but none of the listed models in the service manual match A3ATKUT) and there is (at least) a third type with S/N starting ME1. Finding the part numbers for this third type has been difficult at best.
A: S/N DS2
B: S/N DS1, DS3
X: S/N ME1

Motherboard: P/N: ME1: A3ATHMMA-004 (Board BA3ATHG0 201 3, A3ATK013)
Pics: A3ATHMMA-004 | A3ATHMMA-002 (supposedly either will work)
Locations: ElectroParts (found on eBay, best deal), PartsRunners (free ship, 6mo wrty, 21d return), TVPartsBay (6 mo wrty, 15-day return), I found other sites more expensive. ShopJimmy didn't have my needed part.

Function CBA Unit: P/N: ME1: A3ATHMSW-001 (Type A: A3ATCMSW-001 | B: A3AT0MSW-001)

Other Pages
Previous Page MK808B Plus Android TV Stick for Home Theater GBPVR Next Page
Comments are solely the opionion of the author and not to be construed as the opinion of anyone else.



(c) 2006-2007 - Mark Boyden
Privacy - Legal Stuff - Contacts