ELEMENT ELEFQ462 led/lcd power problem

[ilikesteel]

Re: ELEMENT ELEFQ462 led/lcd power problem

Tom66,

unit plugged into ac outlet, not pressing power on switch.

all 4 pads have 23.5V Tom.

thanks,

frank

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

That's OK.

So, next step.

At red points, please measure voltage (TAB of SMD FET, like testing LDO), I'm expecting nearly the same 23.5V.

At blue highlighted areas, please measure voltage across one of the two SMD resistor devices. They are in parallel so measuring either is fine. (Red probe one end and black probe other end.) Also, please tell me what numbers/letters are printed on these (they will probably be all the same.)

EDIT: Please check the previous four test points WITH power on. Then perform above steps.

[budm]

Re: ELEMENT ELEFQ462 led/lcd power problem

You may want to check the voltage of those regulator, one of the cap looks like it has domed top.
TV power on, Black lead on the chassis, red lead on pin 1, 2, 3. Report the reading of each regulator and the P/N as printed on top. I expect them to have something like 1117 printed on top of the body.

[ilikesteel]

Re: ELEMENT ELEFQ462 led/lcd power problem

Tom66 and Budm,

my confusion.....

Budm do you want me to check the voltages on the smd's after pressing the power on button, or take the readings with the TV just plugged into ac outlet?

Tom66, do you want me to check the 4 pads after pressing the power on switch? remember, after 2-5 seconds what ever is going on it all stops after 2-5 seconds. blue panel goes out and the power switch blue led stops blinking.

thanks so much...again!

frank

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

"blue panel goes out"
You mean backlight goes out?
I thought you had no backlight, maybe I got mixed up somewhere.

Proceed with Bud's test for now. Did you check BLON?

[ilikesteel]

Re: ELEMENT ELEFQ462 led/lcd power problem

tom66-budm,

what I meant by the front panel is when you press any of the front panel soft switches, pwr, menu, channels up and down, source, etc, a blue led lights below the label of each switch. when any of the switches are pressed, that blue led blinks. after pressing power, all blue led's for the switches go out after 2-5 seconds.

The lcd panel has no back lighting at all.

also I checked the voltages at the red markers in the picture, all 4 are 23.5 v.

I'll go and check budm's request for voltage readings and tom's readings.

checked the on/off signal from main board for bl-on. it was .009v with power connected to ac outlet, and did not change when the power switch was pressed multiple times.

thanks frank

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

OK since BL ON didn't change, the backlight is not at fault, it is probably a main board fault then.

[ilikesteel]

Re: ELEMENT ELEFQ462 led/lcd power problem

Tom66 Budm,

tom66, I had 0 voltage across the resistors marked in blue on inverter board.

MAIN board:

all 4 smd's are "BM1117-adj
1112AYT

legend, smd with the tab at the bottom, pins numbered 1,2,3 from left to right.

starting at the bottom left of the picture going up, and the far right smd last.

pin 1 5.2
pin 2 00.1
pin 3 00.1

pin 1 3.7
pin 2 1.8
pin 3 0.6

pin 1 5.2
pin 2 3.3
pin 3 2.0

pin 1 5.2
pin 2 3.3
pin 3 2.0

appreciate your efforts guys,

thanks frank

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

Double check first reg, but it looks bad.

[ilikesteel]

Re: ELEMENT ELEFQ462 led/lcd power problem

budm-tom66

doubled checked the lower regulator.

voltages are as stated,

pin1 5.2 and 00.1 on pins 2 and 3.

any other components I should be concerned about? that cap you pointed out doesn't look bulged to my eye, I can take another picture with a good close up if you want it.

tell me more!

thanks
frank

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

Can you touch the regulator and tell if it is getting hot?
If the set shuts down too quickly you can use freeze spray to tell (or compressed air in a can, invert can to get freeze spray.)
Spray the suspect regulator so you get a frosty covering over it. Then, turn the set on. Does the frost condense?

[budm]

Re: ELEMENT ELEFQ462 led/lcd power problem

Is there P/N printing on that one? It looks bad if it is voltage regulator. Put meter in Ohm mode and check the resistance between chassis and 2, chassis and 3 of that suspect regulator.

[ilikesteel]

Re: ELEMENT ELEFQ462 led/lcd power problem

tom66-budm

power to the ac outlet. touched the smd, and it was not warm or hot

sprayed smd with freeze spray, no change, it did not melt the frost quickly.

ohm readings between chassis and pins 2 and 3:

pin 2 .001

pin 3 .310 ohms

checked on the 2K setting

the writing on the smd is BM1117-adj 1112 AYT

thanks

frank

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

There is a definite short between pin 2 and ground; can you remove the regulator from the board and test the resistance with it removed? (Test the board, not the regulator.)

[budm]

Re: ELEMENT ELEFQ462 led/lcd power problem

I have a feeling it will be the MLCC (Multi Layer Ceramic Cap), or shorted out IC as TOM suggested.

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

Yes... if he has a lab power supply, or a 1.2V NiMH battery + ~2.2-2.7 ohm 5W resistor he can test the board and see what heats up using freeze spray. I have used that method several times before to locate a short, e.g.
http://www.youtube.com/watch?v=7Xz-iSaEAb8&t=3m13s

[ilikesteel]

Re: ELEMENT ELEFQ462 led/lcd power problem

budm-Tom66,

did as suggested. with the smd removed, from gnd to pad 2 I get .001 on 2K scale. also, from gnd to pad 3 I get .000 on 2k scale!

oh my.

thanks frank

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

Pin 3 is ground, or adjust, so that's normal. But pin 2 is output, and that shouldn't be zero ohms, so the short is on the board.

Do you have a lab power supply with a current limit feature?

If not, do you have a fresh rechargeable NiMH? The battery must be rechargeable because they can deliver high currents.

[ilikesteel]

Re: ELEMENT ELEFQ462 led/lcd power problem

tom and budm,

I don't have that special power supply. I do have some AA rechargeable batteries form a camera., those are nicad I think. I do have a ryobe lithium
battery at 18V for a drill.

I'm doomed.

thanks,

frank

[tom66]

Re: ELEMENT ELEFQ462 led/lcd power problem

Check the camera batteries, nicad can deliver high current too.