Emerson LC401EM2F

[Mark369]

I have an Emerson 40" LCD TV that stopped working. I removed the back panel and noticed the 8A 250V fuse near the AC input was open.

I found that D606 is shoted in circuit do you think this would cause the main fuse to open?

I found the drawings for this power board.

Thanks for your help.

[Pentium4]

Re: Emerson LC401EM2F

Yeah I think that would cause the fuse to open, can you post some pictures of the boards?

[Mark369]

Re: Emerson LC401EM2F

no pictures yet. but it looks like this.






Thanks for quick reply

[budm]

Re: Emerson LC401EM2F

Do you have the diagram in PDF format? it is no focus enough to read the part designators.

[Mark369]

Re: Emerson LC401EM2F

yea

[Mark369]

Re: Emerson LC401EM2F

try this.

[Mark369]

Re: Emerson LC401EM2F

ok up loaded pdfs to large to attach full pdf.

[Mr Bill]

Re: Emerson LC401EM2F

I had a sylvania 42" that 1 diode was shorted and the main fuse was blown. I replaced the diode and fuse and the tv came to life. A friend of mine has the tv right now and as far as i know it's still working. It's been about 4 months now. So you might just need to replace the diode and the fuse and be back in business.

[Mark369]

Re: Emerson LC401EM2F

this is a zener diode to ground as far as i can tell does that make a diff

[budm]

Re: Emerson LC401EM2F

Is it d606 or d1606?

[Mark369]

Re: Emerson LC401EM2F

i dont konw much about electronics. so what would that mean?

[Mark369]

Re: Emerson LC401EM2F

iv fixed about 6 lcd monitors just like caps and a voltage regalter

[Pentium4]

Re: Emerson LC401EM2F

i dont konw much about electronics. so what would that mean?

What Diode that's shorted has D606 or D1606 next to its leads

[budm]

Re: Emerson LC401EM2F

That D606 Zener is in parallel with Source resistor for Q601 R609 (0.75 Ohm) that is why is shows shorted.

[Mark369]

Re: Emerson LC401EM2F

ok that would make sence. i guss i will remove D1201, 1202, 1203 and 2104 and test.

they all show open but it is the bridge from what i can tell maybe one or more are part open and shorting and blowing fuse.

[Mark369]

Re: Emerson LC401EM2F

how do you check for leakage

[budm]

Re: Emerson LC401EM2F

OK, discharge c1612 (150uf 450v) first, then take the resistance reading across that cap to see if it shows anything less than 100 Ohms, we are looking to see if you have shorted load which will be in parallel with the cap.
You also have two set of the bridge circuits, the diode you removed earlier are for the standby power supply, second set of the rectifier (D1607~1609) is for the main power that feeds the PFC circuit.
You should also check surge protector SA1601 to see if it shows shorted.

[Mark369]

Re: Emerson LC401EM2F

c1612 on my blue esr meter it shows .33 in the board and on my dmm on the 20M setting it starts at 2.2 and then goes down. sa1601 reads 2.62 on 20M setting and it looks like a blue ballast capacitor i see in lcd smps

[tom66]

Re: Emerson LC401EM2F

Note with these self-oscillating supplies, ANY short on the output (secondary) will blow the primary fuse. There is very limited short circuit protection.

[Mark369]

Re: Emerson LC401EM2F

so from my readings do we know if c1612 is good or do i have to lift a leg