Westinghouse L2410NM No Power, No LED

[smason]

Re: Westinghouse L2410NM No Power, No LED

Sounds like you've got a good handle on things so far.

1. Yes, that's exactly correct.

2. Yes a screw or any pin on a connector that's labelled as ground.

3. Wouldn't hurt, but if they look ok, they probably are.

4. It's possible, lets see what you get on your measurements.

[ben3843100]

I have a Westinghouse L2410NM LCD panel I'm working on. I've read through many other threads detailing similiar issues and have tried take care of the easy steps first. Here are the symptoms and troubleshooting steps I've performed so far:

L2410 LCD Monitor Troubleshooting

• I have no power LED and no image is visible with flashlight shining on screen.
• When the power supply is plugged into an outlet I initially hear a faint electrical sound like the board is powering up. (capacitors charging?)
• I do not hear a faint clicking from the power supply as described in the other L2410NM thread so I'm assuming the power supply is not attempting to "start up."
• I have replaced all capacitors with high quality Rubycon and Nichicon 105 degree caps.
• I triple verified capacitor polarity (- strip towards board marking)
• I have checked all three surface mount fuses on the board with my Craftsman 82141 multimeter and all check out good at 0.3 ohms. Multimeter with leads touching also measures 0.3 ohms so fuses seem ok.
• I checked the 4 bridge rectifier pins circled in blue on the back of the board for short as described in another thread. I numbered the pins 1-4 and placed my multimeter on 200 ohms. With power off and board removed, I measured pins 1-2, 1-3, 1-4, 2-3, 2-4, 3-4, and in reverse. My multimeter read 1 for infinity in both directions on all pins; no readings were under 30 ohms.

Other information:
When I test the power supply board I screw it back onto the monitor frame so it is grounded and connect all wires so there was a load on the board as suggested in other threads.

Assumptions:
I'm assuming this problem is related to either the power supply or the video board (or both), and not the inverter board. If the video and power supply board were working correctly, I'm assuming I would be able to power the monitor on and be able to see the image with a flashlight even if the inverter board were faulty. Since the buttons to power on the monitor connect to the video board, I'm assuming the video board could also be the source of the problem.


Next steps:

1. Check for mains voltage (like 120V or 240V DC) at the main filter capacitor at 1.4x the line voltage. (Do I set the meter to 600Vdc and measure between the two large cap wires?)
2. Check for 3.3V, 5V, or 12V DC on the logic card. (Do I measure from a chassis ground to the exposed metal on each ribbon cable plug?
3. Resolder transformer pins? All solder joints appear to be good. No cold solder or cracking found.
4. Shorted transistors? Another thread stated that shorted transistors often lead to shorted fuses, but all of the fuses on the board test out ok.

Thanks in advance for the assistance.

P.S. I'll post better front and back pics of the video and inverter boards tomorrow when I can get some pics next to a bright window.