Emerson LC401EM2F

[selldoor]

Re: Emerson LC401EM2F

Not read if it is ultra fast but it is only 400v not 600 spec sheet attached
maybe ok for testing but I dont really know.
Perhaps other will know for sure.



Edit
Not even fast let alone ultra so if its in the PFC circuit I guess its no good.

[lilmonk3]

Re: Emerson LC401EM2F

http://www.radioshack.com/product/in...ductId=2062579

Would that work and be safe to use???

[lilmonk3]

Re: Emerson LC401EM2F

Do I have to stay with the exact spec of this diode.. I would LOVE to be able to run to ratshack to get a part that will work.. I am wanting to try to see if I can get this thing going by monday. My nephew is home from college for the holiday weekend and I wanted to give this TV to himm.. Any chance that ratshack would have something that would work??
Its a SF38,DIODE, ULTRA-FAST, 3A, 600V

[lilmonk3]

Re: Emerson LC401EM2F

Thanks retiredcaps. Its sf38 .. Looks like I will have to order online.. Was hoping Ratshack would have something I could use just to get by.. Oh well

[retiredcaps]

Re: Emerson LC401EM2F

Ok here are the readings of the diodes in pic 1 and 2 with one leg lifted..
D1604 00.3 00.2

D1604 is bad if that is tested out of circuit.

[lilmonk3]

Re: Emerson LC401EM2F

Ok here are the readings of the diodes in pic 1 and 2 with one leg lifted..
D1201 OL 4.60
D1202 OL 4.90
D1203 OL 4.39
D1204 OL 4.21
D1604 00.3 00.2
D1606 OL 2.94
D1607 OL 4.84
D1608 OL 4.73
D1609 OL 5.26
D1610 OL 5.05

I marked up the board in the pics below .. My eyes are not very good either

[budm]

Re: Emerson LC401EM2F

Set meter to Ohm mode, auto range is fine, we are looking for shorted parts which will no longer act like semiconductor any more, it will read low Ohm in both directions.
Again, take the reading of the bad part off the board when it shows bad on the board to verify, you can just lift one leg off the board and take the reading also.
This power supply uses dual PFC circuits. The two MOSFET's may be shorted out, the B+ to the PFC is supply through the relay, so if the main is not connected, the PFC will not get any power to it, which is why it did not blow the fuse when main board is connected, the 5VSTBY SMPS is before the relay so it is always running with its own rectifiers which is OK since it did not blow the fuse.
I cannot see the number too well in the pictures.
Where are the D1604,D1606? Are they in the second pictures? the group of 4 in the bottom left of pic#2? My eyes are not that good.
This is what I come up with. The MOSFET or DIODE for the PFC may be shorted, or MOSFET for the SMPS may be shorted also.

[tom66]

Re: Emerson LC401EM2F

I am unsure on whether this is based on a self-resonant topology or not. It looks like it might use a controller IC. However, I was playing around with a real cheap wall wart today which used a self resonant circuit. When I shorted the output, it blew the mains fuse! So some of these self-resonant designs don't cope well with shorted loads.

[budm]

Re: Emerson LC401EM2F

OK, please check the resistance of the Diodes I red-lined in picture 1 & 2 tell me what you get.

[lilmonk3]

Re: Emerson LC401EM2F

And yes it blows the the fuse as soon as its plugged in if all boards are connected.. But if I unplugg the flat white ribbon cable that goes from the PS to Mainboard the fuse does not blow

[lilmonk3]

Re: Emerson LC401EM2F

I have an auto ranging DMM.. I have ohm and diode setting... No 200 ohm.. Which one would you like me to use.. I did just do some quick checking with it in diode mode and D1604,D1606 read 000 both ways, D1607 reads .488 and .493

[budm]

Re: Emerson LC401EM2F

It is blowing the main fuse the minute you plug it into the outlet?
Please check the resistance reading (meter set to Ohm mode 200 Ohm range) for me as noted (board not installed or plug in).

[lilmonk3]

Re: Emerson LC401EM2F

Thank you for the help Budm

[budm]

Re: Emerson LC401EM2F

I rather use yours clear pictures since other board may not be the same revision, it is already hard enough try tracing the connections without having the board in front of me while toggling back and forth between the picture of the top of the board and bottom of the board to get correct part locations. I may ask for closed up later.
Can I get the picture of the top board that I can see the whole board, your earlier pictures cutout part of the board.

[lilmonk3]

Re: Emerson LC401EM2F

If those are not good enough, another member posted some pics here https://www.badcaps.net/forum/showth...M2F#post250318

Its cloudy here today and I have crappy lighting in my house

[budm]

Re: Emerson LC401EM2F

At this point I will need really good clear pictures of the bottom side of the board to trace out the connections and see how these Diode are hooked up. They tested OK out off the board.

[lilmonk3]

Re: Emerson LC401EM2F

Ok all of the following out of circuit..
D606 OL .663
D1215 OL .547
D1603 OL .660
D1401 OL .653

[budm]

Re: Emerson LC401EM2F

I always test them out off the board when they read bad/strange on the board, it just a way to verify for sure.

[lilmonk3]

Re: Emerson LC401EM2F

D606 may be in parallel with something with low Ohm usch as inductor/transformer widing or very low Ohm resistor.

D1215 .027 .027
D1603 .125 .142
These two looks bad, are you measuring them in the circuits or they are removed?

Bud.. the only one out of circuit in those reading was d606

[budm]

Re: Emerson LC401EM2F

D606 may be in parallel with something with low Ohm usch as inductor/transformer widing or very low Ohm resistor.

D1215 .027 .027
D1603 .125 .142
These two looks bad, are you measuring them in the circuits or they are removed?