Emerson/Funai LF46EM4 no image

[R_J]

Re: Emerson/Funai LF46EM4 no image

The manual 50ME313V_F7 shows ic3601 and the cap. C3602 220/6.3 is listed as being on the output that feeds ic3001, If there is a short there, I see a bunch of 0Ω and inductors off that line, If you can find them you can try removing them one at a time you migt know which line has the short, and if you are lucky it will be one of those .1uf caps

[Josh86]

Re: Emerson/Funai LF46EM4 no image

You could, you should have voltage on the input of that regulator, that cap seems to be across the input so if it measures short, the cap could be bad, the regulator ic next to it or something before the regulator
What schematic are you using?

Model type B, starting around pg. 50.

ALSO; just did some more searching for a Magnavox 46" and I came across a post from budm that linked a 46" set...though it doesn't reference Emerson as a model. I may look at that too.

https://www.badcaps.net/forum/attach...8&d=1487816733

[R_J]

Re: Emerson/Funai LF46EM4 no image

You could, you should have voltage on the input of that regulator, that cap seems to be across the input so if it measures short, the cap could be bad, the regulator ic next to it or something before the regulator
What schematic are you using?

[Josh86]

Re: Emerson/Funai LF46EM4 no image

If the cap is not shorted you could have a shorted regulator ic3601 or somethiing that is on that ic's input is shorted

Could I just start checking voltages on the ICs as a method to determine whether or not components might be the cause of failure? I don't have a schematic for this particular set, but I'm working off one that seems nearly identical.

[R_J]

Re: Emerson/Funai LF46EM4 no image

If the cap is not shorted you could have a shorted regulator ic3601 or somethiing that is on that ic's input is shorted

[Josh86]

Re: Emerson/Funai LF46EM4 no image

I'm unsure, but is there anyway to test an in-circuit cap with a multimeter? Is disconnecting the cap or using an ESR the only way?

[Josh86]

Re: Emerson/Funai LF46EM4 no image

Thanks; it's good to at least hear another opinion on it. My wife told me to immediately throw it away (usually she's always right).

Before replacing the backlight, the board/display was working, but shutting down because an entire row was out. Sometime during the breakdown I must have unseated a cable or shorted something because I was getting bad readings out of the LVDS to the TCON (and the cable was was hot to the touch on the supply line/pins). That problem is since gone, but now I get nothing on the display.

What I'll do is see if I can desolder the existing EEPROM. If it goes well; I'll order a new one (from shopjimmy since I don't know if I can trust the flash/programming from random ebay sellers -- I'll pay about $5 more, but I'd like to be sure).

I do see similar mainboards I could get (an Emerson 50" compared to my 46" , but I have no idea if the programming would cause display issues or even work with my panel correctly). I don't know anything about what's on those EEPROM ICs, but in my wild imagination I'd assume there may be something there for either proportion/display sizing along with the menu system and available features of the set.

If it doesn't work out, it's going to be parted/recycled and off the table in the garage. I need to make some space.

[nomoresonys]

Re: Emerson/Funai LF46EM4 no image

You might want to try a 15 dollar eeprom, if that don't work, I'd try to find another tv to fix, I don't trust emerson, especially after reading the reports.

[nomoresonys]

Re: Emerson/Funai LF46EM4 no image

You might have a money pit there, emerson gets some pretty bad reviews, here's some consumer affairs reports: https://www.google.com/search?client....0.I4ktGq8Z1H4

[Josh86]

Re: Emerson/Funai LF46EM4 no image

Took the aluminum frame off the bottom of the display to look for visible damage to the LCD board but I could see none. I tested caps that my leads were small enough to get at and the one's I checked were OK. LCD board also has labeled test points; but I did not take measurements.

The FETs on my old T-Con were OK.

My new T-Con arrived and I hooked it up only to the mainboard. I got the same exact voltage readings on the new T-Con. Afterward I connected the LCD and still no picture.

Still unsure if the panel could be bad or if mainboard is the problem (remember I also do not receive any audio to the best of my attempts to switch to active input). Service troublehooting in a similar 39" Funai suggests these two possiblities as the issue. Options for mainboard look like either an EEPROM chip ($15) or send it in for repair ($55+shipping). I cannot find a direct replacement for the mainboard on this model TV. I could also try a board from a similar set if one exists (~$30) just to see if I get anything on the display. At that point I'd be sinking ~$100 already into a $400 set that still may not work. Spent about $30 for the backlight and new T-Con already.

[Josh86]

Re: Emerson/Funai LF46EM4 no image

Haven't been able to look at the set for about a week but...

I'm ordering a t-con board because they can be had for ~$10.

I went through the troubleshooting flowchart on a 39" Funai (all the connectors/pinouts identified the same) and I end up with the result that it's either the mainboard or a bad panel. The "no video" tests had me check for certain voltages at specific pins on both the mainboard and connection to the t-con. They ended up coming out as expected which leads to the suggestion of replacing the main CBA or a defective/bad panel. I fear the latter because I moved it around a bit during disassembly to fix the bad backlighting. Maybe there's a short to the aluminum framing; who knows. I could pull it back out of the chassis and see.

Before I put the t-con in I'm going to check the only FET on the t-con board. I read some other posts (and saw the shopjimmy video) about how a bad panel can often be the cause of damage to the t-con.

I'm still a little concerned in the case of either a bad t-con or bad panel that I'm still not getting any audio, which I can't see that issue being anything but something on the main CBA board.

[Josh86]

Re: Emerson/Funai LF46EM4 no image

I can certainly order a T-Con, though I'm concerned it may not work because I'm not getting any audio output over composite/component. I can't find a service manual for these Funai 46" sets (either Emerson or Magnavox) but I looked at some schematics and block diagrams from both 32" and 39" Funai sets and I don't see anything going over the LVDS to the T-Con that has much to do with the audio interface on the L/R inputs.

I guess I'd just like my concerns to be proved wrong or explained -- because a $20 T-Con would be great if it were to fix the problem. I just have a gut feeling there something on the mainboard and finding or fixing that is a lot more hassle.

Really wish I had a service manual specific to this model type -- but I think I'll take a look at the Funai 39" service manual to see if there's similarities in testing.

[Andrew F. Ali]

Re: Emerson/Funai LF46EM4 no image

.

[Josh86]

Re: Emerson/Funai LF46EM4 no image

Some of those T-CON Bd readings are off. I think you should get anew T-CON Bd and give it a try.

Which voltage readings do you suspect are abnormal from expected voltage? This way I can retest and confirm before before I order a new T-Con board.

Thanks!

[Andrew F. Ali]

Re: Emerson/Funai LF46EM4 no image

Some of those T-CON Bd readings are off. I think you should get anew T-CON Bd and give it a try.

[Josh86]

Re: Emerson/Funai LF46EM4 no image

Remeasured and the CPV testpoint area reads as follows:

CPV3 = 2.407 (taken the day before)
CPV4 = 2.37 V
STV2 = 2.37 V
CPV1 = 2.37 V
(?) USI_SYNC = 1.77 V
CPV2 = 2.11 V

[Josh86]

Re: Emerson/Funai LF46EM4 no image

Reattached marked up image with voltage reads.

So looking at the reads I thought "where is CPV1 if I'm reading CPV2"? I then realized I actually never read CPV2; I used the top test point which was likely for CPV3. I completely ignored all the rest of the labels and just looked at that highlighted box -- whoops.

If you really need CPV2 (I assume it's an important signal), I'll have to wait until I'm back home to check it out and I'll record all those values on those test points. In the meantime, if there are any other points you want me to check (either here or on mainboard) I'll note those and get the reads.

Really appreciate the direction/help.

[Josh86]

Re: Emerson/Funai LF46EM4 no image

I can see some Voltage test points on the T-CON.

Reattached marked up image with voltage reads.

[budm]

Re: Emerson/Funai LF46EM4 no image

I can see some Voltage test points on the T-CON.

[Josh86]

Re: Emerson/Funai LF46EM4 no image

I've tried checking for sound with an input source but with no luck.

Is it possible it's still the T-Con board in this situation or is that a sure sign it's the mainboard? I don't know anything about how the logic works between any of the chips/boards without seeing a block diagram (and even then I may not understand it), but I wonder if the mainboard wants to see/confirm some output from the T-Con coming back for everything to work (including audio output). If anyone knows of a link to a service manual for this line of units, that'd be cool to look at.

A new T-Con can be had for $20 or less it seems, whereas the mainboard is just hard to find, expensive, or will have to go to someone for a repair (~$50 average). The only other common parts I am seeing for a mainboard fix is an EEPROM IC. EBay does have a 20% sale today and I could use that on a mail-in repair service to get the cost down a little.

On the flip side, I like tinkering and it would be fun to find out exactly what isn't working (I'm not necessarily in a hurry) and I could desolder and put a new component in as long as it wasn't too small. I live in a very rural area and before Radioshack became defunct it was really the only local place to get electronics. I'd be ordering pieces online if I were to replace anything on a circuit board (can't even buy a simple resistor anywhere in 100 miles unless I salvage it from something).

So, if not I'm not replacing either board entirely, I can take my time trying to figure it out. If nothing comes of this I'll end up throwing the set away in the future unless anyone is interested in parts.