Emerson LC401EM2F

[ikapitan]

Re: Emerson LC401EM2F

Hi all, my philips was also blown by the surge. I ordered a kit from shopjimmy to replace as per their recommendations for blown fuse. Found some rectifiers dead and replaced them all, aslo D1208 and IC1201. i used the BUDM's light bulb test. Looks like the parts from the kit were not same nominals. I crosreferrenced them on Mouser.com. Ordered the right Zener Diode D1208 and rectifiers. Now all in the light is on all the time and IC1201 is getting very hot. What else can i test? any ideas?

[DesertRat]

Re: Emerson LC401EM2F

I too replaced D1208 and have a working TV again. Had it on all last evening and works like a charm! Thanks Mark369, and budm for your work and dedication on resolving this issue.

[DesertRat]

Re: Emerson LC401EM2F

Bud, in the picture attached are the voltages I got this morning after removing D1208 from the board, and checking R1201 that checked out to be good. Diode 1208 on my board was definitely bad, it had a gaping crack all the way down the side of the diode.

Are those voltages within range?

I did turn on the TV and the screen lights up and everything seems to work normally, however, I didn't leave it on long for fear it might do some damage with the missing diode. I was curious to see if it would come on or blow the fuse. Which as you probably guessed is why I didn't have anything at the moment from earlier. I had to round up a good fuse since the one in it was blown.

[budm]

Re: Emerson LC401EM2F

The fusible resistor R1201 which you should check to see if it is OK, it is 1 Ohm resistor.
BTW, the connection of the Zener Diode D1208 does not match the diagram in post 1, it is not snubber diode, the snubber diode per board layout is D1205 along with the the C1202, R1202, R1203 which form RCD snubber network.
The circuit should work without Zener D1208 in place.

[budm]

Re: Emerson LC401EM2F

I cannot tell from the pictures as to what those resistors are used for.
BTW, I hope the SMPS IC is not damage when that snubber diode was not connected.

[DesertRat]

Re: Emerson LC401EM2F

That is the snubber diode for that STBY SMPS IC, it looks to like there was cold solder joint so it heats up due to contact resistance. I would replace it.
Are you getting the STBY Voltage?

Hi Bud, I'm not getting anything at the moment. I've got a diode ordered and waiting for it to arrive (should be here by Tuesday). I thought I'd replace it and then see what I have. Once I get a new one I'll post any new findings either way. It also has a brown heat mark around resistors R607-608-610-613. Would this be from the diode, possibly indirectly?

[RJARRRPCGP]

Re: Emerson LC401EM2F

LOL@ 2000W fuse...

Even if it was a CRT, that's likely more current than needed for the fuse.

Yes, CRTs OTOH have an inrush current, but that's probably more to do with the primary caps. But 8A???

[budm]

Re: Emerson LC401EM2F

That is the snubber diode for that STBY SMPS IC, it looks to like there was cold solder joint so it heats up due to contact resistance. I would replace it.
Are you getting the STBY Voltage?

[DesertRat]

Re: Emerson LC401EM2F

I was looking over this thread since I'm working on this exact problem. Here's what I found when I first looked over the PS board.. On D1208 as mentioned in this thread, there were heat signs on the top side of the board. On the bottom side, you can see the solder is missing on one leg of the diode.

So my question is, do you think part of this problem is caused by cold solder joints on the diode D1208? I intend on replacing the diode, I'm just curios if anyone else has found something like this?

[tikito]

Re: Emerson LC401EM2F

Ok, problem solved.
After a few days troubleshooting i found that the problem was a broken ribbon flex cable,the connecting the power supply board with the main CBA AV Board.
Was not visible damage,was broken internally, however testing continuity,wasn't any signal,so carefully i inspect it,found the problem and repair it.
I put everything back together and bingo,works like new.
Thanks guys

[tikito]

Re: Emerson LC401EM2F

Hi guys,thanks for the good info in this forum.
I need some help with this same board,it was blowing the fuse and i went checking everything explained here.
this is the list of parts changed:
Rectifier diodes 3 were short,replaced all 4.
D1208 Short,replaced.
As the manual i have the 4.3v all good buy i got nothing after q1201 and q1202 going to the relay.
My question is:
Are those transistor in charge of the power on cycle,or is any other part could be bad?

The fuse do not blown any more,i have power before relay but after relay nothing.

Guys thanks in advance.

Chris M

[JDC]

Re: Emerson LC401EM2F

Here's a pic from the service manual if it helps.

[JDC]

Re: Emerson LC401EM2F

Replaced the diode in question, now instead of the light bulb staying on constantly, it rapidly blinks for about 5 seconds and then dims for about 2 seconds. The front panel LED blinks red 15 times.

I was told this set broke after a lightning storm. I found a burnt trace on the board and attemped to repair it. Can anyone check my work?

[JDC]

Re: Emerson LC401EM2F

Same TV, same dead diode. Ordered the part today from mouser, will let you all know how it turns out.

[Mark369]

Re: Emerson LC401EM2F

im glad to see that this post has helped a lot of you guys.

@coreyand

if you want to fix this tv you might tell us some more info.
and we will need pics of the boards inside top and bottom.
good luck with your quest of learing.

[selldoor]

Re: Emerson LC401EM2F

Personally I would say learning electronic repairs starting with a TV is a bad idea. You should start with something simpler like a monitor. Emerson Tvs seem particularly bad I have seen many on here where we were unable to fix it. Often blown components kill off the eeprom. So yes you can use it to practice on and practice soldering and testing but dont be too disappointed if it dont get fixed. Guy in post 96 seems to have had a simple fix.
I understand with caps you can use a larger voltage rating as long as the uf value is the same - that is correct usually one step higher in voltage..

You can also go one step higher in uf and when you REALLY know what you are doing
you can sometimes go one step lower in both - but I wouldnt try that.
Here is a good starter guide - written for monitors, but the tests are the same.
https://www.badcaps.net/forum/showpo...4&postcount=19

The internet is the best place to learn most things - google is your friend.

Google "emerson D1208"
For values of specific components a schematic/service manual might help

[coreyand]

Re: Emerson LC401EM2F

I have a TV same model that I just purchased from somebody at a garage sale, I am not an expert at this by any means but I have fixed some much older LCD displays by replacing bad caps. I understand with caps you can use a larger voltage rating as long as the uf value is the same(I hope that is right). Maybe its the other way around, perhaps the voltage is supposed to be the same but the UF value can be larger than specified. Please correct me if I am wrong on that. Either way I am wanting to learn how to repair electronics because I come across a lot of bad components in my line of work(Audio/Video/Home Theater Business 8+ Years) and would like to repair said items that we replace because they quit working either by hardware defect or mother nature(Lightning).

Repairing this TV will be my first for replacing anything like diodes and what not so I want to use this tv to familiarize myself with things to look for. I have watched a few videos on youtube but none that pertain to this tv specifically. I apologize this probably isnt the best thread to announce all of the above said information but I have read over this thread and the other one mentioned in this thread that both pertain to this set, and I needed to know if it was indeed the D1208 diode that was replace that solved this problem. If so, when shopping for a diode to replace where is the best place to learn of the values of diodes and be able to understand what values of a diode I need to replace the above mentioned one? Also, I see that the diode is a "zener". If somebody could explain this to me or point me the correct direction that would be much appreciated. I would to go to radioshack and get this "zener" d1208 diode and replace it but I feel like d1208 only pertains to this board as a marker of diode placement. Thank you all very much.

[selldoor]

Re: Emerson LC401EM2F

Well Done ! Tip - next lightning storm unplug the tv and aeriel

[phil10]

Re: Emerson LC401EM2F

I followed this thread all the way through and replaced diode 1208 and fuse on a Emerson LC401EM2F power board. Turned it on and now it works great. thank you all for the help. Next lightening storm I will look for the same things. Thanks

[joshbsg]

Re: Emerson LC401EM2F

The service bulletin for this model lists: "Cure: Remove the diode, replace fuse. Do not replace the diode. Perform any additional repairs as necessary. "