Emerson LC401EM2F

[JDC]

Re: Emerson LC401EM2F

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

[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

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

[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

[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

[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?

[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?

[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???

[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?

[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.

[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.

[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.

[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.

[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?