Need help identifying this resistor (LG power supply)

[ComputerGeek]

Re: Need help identifying this resistor (LG power supply)

Sometimes you do but not always, I was able to leave them in on my thread.

I would test them in and post the measurements back and then pull them if you have too.

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

Tested in circuit:

Q1009
-----------
S - G = 31.2 ohms
S - D = .2 ohm
G - D = 31.4 ohms

Q1011
------------
S - G = 1.9 ohms
S - D = .1 ohm
G - D = 2 ohms

[budm]

Re: Need help identifying this resistor (LG power supply)

They look dead short!, remove them from the board and test them, more likely to be bad, and they may have taken out the IC and the Gate (G) drive resistors and Diodes with them also.

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

Testing OUT of circuit:

MOFSET 1
-----------------------
S - G = 62.2 Ohms
S - D = .2 Ohms
G - D = 62.4 Ohms

MOFSET 2

S - G = 2 Ohms
S - D = .2 Ohms
G - D = 2 Ohms

[retiredcaps]

Re: Need help identifying this resistor (LG power supply)

Testing OUT of circuit:

MOFSET 1
-----------------------
S - G = 62.2 Ohms
S - D = .2 Ohms
G - D = 62.4 Ohms

MOFSET 2

S - G = 2 Ohms
S - D = .2 Ohms
G - D = 2 Ohms

Both are shorted (bad).

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

Ok, since both MOSFETs are shorted I can replace them. My question is, what happens when I replace them and another component down the line is bad? Will it short the MOSFETs again? Is there more testing on other components I should do before replacing them? I don't have a lot of experience soldering and un-soldering SMCs but I'm willing to try whatever it takes.

[budm]

Re: Need help identifying this resistor (LG power supply)

Please see PDF, we need to find out if other components are damaged or not also, leave the MOSFET's off the board. I have seen a lot of this kind of failure, most of the time it will take out the output section of the IC with it. We will measure the output pins and other pins as well of the IC once we get the P/N to look up the spec sheet.

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

Thanks for everyone's quick replies!
Special thanks to budm for the step-by-step help!

Resistance at D1016 = infinite
Resistance at D1017 = 1.786 kilo ohms
Part # on IC = DLA001D

[Toasty]

Re: Need help identifying this resistor (LG power supply)

You really don't need to test them. The fact that the resistor blew both times indicates that one or both of the MOSFETs are bad. As I mentioned before, you do need to replace both of the MOSFETs at the same time.

You probably don't have the equipment to test that capacitor so I would recommend replacing it and the two MOSFETs and the resistor and see how it goes.

How close was this lightning strike? Was any other equipment damaged in the home? This may end up being an exercise in futility as other parts of the television may have been damaged by the strike.

Toast

[budm]

Re: Need help identifying this resistor (LG power supply)

When MOSFET shorted out at first, it may have Gate to Drain shorted out due to GATE insulation breakdown first then that 400VDC will flow through Drain and the GATE of the MOSFET and resistor diode to the gate output drive of the IC, I rather check than not checking, does not take much time to do.

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

I do have a multimeter that is supposed to be able to test capacitance. I found a data sheet on the IC but don't know how to test. Is C1025 what needs to be tested?

[budm]

Re: Need help identifying this resistor (LG power supply)

Can you post the data sheet so I do not have to google for it?

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

OK, so the datasheet I thought was correct was for something else completely. I can't find an exact match for DLA001D but I did find a thread on this site (https://www.badcaps.net/forum/showthread.php?t=17254) that says it may be a L6598 chip. I have attached the datasheet for L6598

[budm]

Re: Need help identifying this resistor (LG power supply)

Check Pin 11 to Ground and 15 to ground, using the same ground point I told you earlier in the "TEST FOR SHORTS.PDF"

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

I'm not sure exactly where pin 1 is (there's no notch) I'm assuming pin one is on the bottom left when looking at the chip with the etching right side up. (See attached Pins.pdf)

Pin 11 = 1.748 kilo ohms
Pin 15 = infinite

[budm]

Re: Need help identifying this resistor (LG power supply)

Please see PDF.

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

Kind of hard to tell from my pic but that's how I was reading it. Thanks for the tip on the white mark.

Pin 11 = 1.748 kilo ohms
Pin 15 = infinite

[budm]

Re: Need help identifying this resistor (LG power supply)

Well, it does not show as shorted. You can try new MOSFET's and see what happen.

[ecallenil]

Re: Need help identifying this resistor (LG power supply)

MOSFETs (STP20NM50FP) ordered. I'll post when I get them and we'll see what happens.

Thanks again everyone!

[Toasty]

Re: Need help identifying this resistor (LG power supply)

Did you order the cap?