LC401EM3F Emerson Inverter Issue

[dcapper]

I had posted earlier that my power supply was dead. Repaired that with new 2561a chips. Now I have an issue with the inverter I believe. I get my 24v coming in from the power supply and into the gates but nothing out. There is 4 diodes that are reading shorted. I haven't removed them to see if if they are only shorted in circuit. They are stamped UH. The inverter is an Samsung LJ97-03241A (SSI400_08A01) backlight inverter. I saw another post Budm was working on one. I get audio and no video. Not even a blink of light or voltage at the coils on power up. The diodes shorted in question are D101, D102, D201, and D202. If someone has one of these inverters, could they meter theirs to see if there's is shorted? I hate pulling out those smd diodes. Oh and I am getting around 600 ohms across the coils.

[budm]

Re: LC401EM3F Emerson Inverter Issue

Those diodes are for the MOSFET Gate discharge, the diode is connected in parallel with low Ohm resistor. I.E. D101 is connected in parallel with R101 which are connected to the Gate of Q101.
So did you see the backlights even flash once?
What DC voltage do you get at pin 12 ENA (BACKLIGHTS ENABLE) when TV is OFF and when Power ON?
http://www.shopjimmy.com/samsung-lj9...t-inverter.htm

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

Those diodes are for the MOSFET Gate discharge, the diode is connected in parallel with low Ohm resistor. I.E. D101 is connected in parallel with R101 which are connected to the Gate of Q101.
So did you see the backlights even flash once?
What DC voltage do you get at pin 12 ENA (BACKLIGHTS ENABLE) when TV is OFF and when Power ON?
http://www.shopjimmy.com/samsung-lj9...t-inverter.htm

I noticed the resistors after you mentioned it.

Power on

Pins 1-5 = 24v
Pins 6-10 = GND
Pin 11 = 0v
Pin 12 = 1.32v
Pin 13 = 0v
Pin 14 = 1.59v

Power off

Pin 1-14 minus 12 = 0v
Pin 12 = .9v for a bit. Now all 0.

Any of them look off?

[budm]

Re: LC401EM3F Emerson Inverter Issue

They look OK, the ENA is on the low side but probably enough, but we can try using 3Vdc from batteries to see if it will work, but you will have to disconnect that ENA wire from the connector so the 3V will feed back to the main board. But did you see lamps flashes for seconds?

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

They look OK, the ENA is on the low side but probably enough, but we can try using 3Vdc from batteries to see if it will work, but you will have to disconnect that ENA wire from the connector so the 3V will feed back to the main board. But did you see lamps flashes for seconds?

Not once. I never saw a flash of light at all. This tv started off with a power supply problem. Maybe there is something else still wrong in it.

[budm]

Re: LC401EM3F Emerson Inverter Issue

Is there a cable connected to connector CN102?

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

No cables connected to it. Nowhere to connect it to on the tv from what I can see.

[budm]

Re: LC401EM3F Emerson Inverter Issue

Hmm, I am running out of idea, we need to get the P/N of that PWM IC U1 (20-PIN) to get the pin out so we can check the voltage on the pins.

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

Bud they are pretty cheap on ebay. Like $10 shipped. Wondering if I should order another one?

[budm]

Re: LC401EM3F Emerson Inverter Issue

The IC or the inverter board? Inverter board is only $25 at Shopjimmy.

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

The whole inverter board. There is a few different sellers on ebay selling them. Here the chip number on the inverter. SS1091SN CA7013.1T 1147A1

[budm]

Re: LC401EM3F Emerson Inverter Issue

That is good price.

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

That is good price.

If they work right? From my symptoms does it look like I have a faulty inverter?

[budm]

Re: LC401EM3F Emerson Inverter Issue

It does, since you do have 24VDC and the enable signal, BTW, that 10A fuse is good right?

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

Yes I tested the fuse and the 4 fet's. There is no shorts in them but it's not passing voltage through to the coils (that's what led me to believe that those 4 diodes could be faulty). Maybe that ic is bad. It's a cheap enough to do a test.

[budm]

Re: LC401EM3F Emerson Inverter Issue

You can check and see if there are voltages on the pins of the IC.

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

I won't have time tonight but I'll look tomorrow. I ordered one on Ebay for $9.00 shipped.

[paulstef]

Re: LC401EM3F Emerson Inverter Issue

I won't have time tonight but I'll look tomorrow. I ordered one on Ebay for $9.00 shipped.

How did it work out in the end?

I have the same TV, but obviously with a faulty transformer.

[dcapper]

Re: LC401EM3F Emerson Inverter Issue

Wasn't the inverter. Should have noticed that when I hit the power button the 3v pins are ok for 2 seconds then it goes to 1.5v. I would assume it's the power supply now but I metered everything and couldn't find a fault.

[budm]

Re: LC401EM3F Emerson Inverter Issue

Wasn't the inverter. Should have noticed that when I hit the power button the 3v pins are ok for 2 seconds then it goes to 1.5v. I would assume it's the power supply now but I metered everything and couldn't find a fault.

So you still have 24V, then I would use external 3V (2 AA batteries) to feed the inverter on if the new inverter is good then the backlights should come on, you will have to make sure the wire connected the inverter on pin which goes back to the main board is disconnected.