No picture power ups blacklights work no menu no

The power supply board has gone bad.It would be more cheaper and easier to buy a new TV than to try and fix the TV that is not working.

Sounds like the main board is going out. It tells everything when to do something and what to do. It even tells the power board to send power to the backlights.

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Going by what all you have changed with no results its sounding like the actual CCFL lights are bad or at least one of them...there should be several sets of wires going to them from the inverter board, you can unhook them one at a time and see if you get some light on the screen, unfortunately though it sounds like the set may be on its way to the recycler. I assume if you look in the back of the set with the lights off you don't see any light.

Check the -12 at the power supply. May be a corroded connector between them. Also look for signs of heat damage. If the power goes through any connectors, get some contact cleaner, disconnect each one and clean both sides of each connector. If that doesn't work, the power supply is probably bad.

Check whether CCFL lamps are good or not. Check whether the newly replaced back-light inverter functions well.

I am working on the same power supply right now, my has a bunch of bad caps that I already replaced but I did not try to turn it on yet becuase I see that RS1 and RS8 are missing, some one had try to fix this power supply. Can you please tell me the value of these two resistors? Please see my pictures at http://s807.photobucket.com/home/budm/allalbums
Your problem sound like the logic board problem, I can tell you what you should have if I can find out if these two resistors were left out from the factory or some had removed them. I fixed the same power supply for the N2652 but I did not take the pictures of the board, I wish I did.

Sounds like a power supply failure, System should accept a standard ATX power supply
http://support.dell.com/support/edocs/dta/P60L/00000023.htm

I had the same problem. In the menu, the image button was grey, and could not be hi-lighted, and the screen stayed blue. I was using the AC power cord. I plugged in the DC power cord instead, and it "woke" the unit up. I switched back to the AC power and it works fine. If you don't hve the DC cord that came with the TV, try andy 12 volt dc output cord with a positive tip.

There is a list of things you need to check, but offhand I'd say that the 5 volt line is low and probably right on the"edge", which is why it works sometimes and not others take a look at this list:
Cause #1
1. (Lamp may light and go out) suspect bad lamp part # 915P020010 2. Check for
12-volts DC at J-9 connector pin 4 on the Engine Driver PCB, if missing check
for an open F9A09 on the Power PCB, if it is open replace F9A09 part #
283P127060 and the Light Engine part # 939P977010 3. (Lamp may light and go out)
Check for 5-volts DC at J-9 connector pin 1 and 2 on the Engine Driver PCB if
low or missing check C9A37 and C9A38 both 3300 UFD 10 V part # 181P732040 on the
Power PCB (part # 930B921002) 4. At power on the lamp turns on and off three
times and then the unit shuts down with a red lamp LED (lamp error). Replace the
Light Engine part # 939P977010 5. Lamp enable line at J14 pin 6 does not switch
to 5 volts after turn on, 12 and 5 volt supplies are good. Suspect the Light
Engine part # 939P977010 6. Lamp enable line at connector J14 pin 6 on the
Engine Driver PCB switches to 5 volts after turn on and does go to 0-volts (low)
after 5 seconds, 12 and 5 volt supplies are good. Suspect the Lamp Power PCB
(ballast) part # 939P978010 7. Lamp enable line at connector J14 pin 6 on the
Engine Driver PCB switches to 5 volts after turn on but does not go back to 0-
volts (low) after 5 seconds, 12 and 5 volt supplies are good. Suspect the Light
Engine part # 939P977010

I would say try #3 first, the two caps on the pwer supply board. A couple of warnings: as always, unplug the unit before servicing. The power supply is located on the left side, if you behind the unit. It is in a shielded box and the shield has VERY SHARP EDGES so use care when you try to open it or you will slice your fingers.
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The power supply failed. It could also be the lights malfunctioning but is very unlikely.
The 5 volts DC line is not providing a proper voltage to the circuitry. 12 volts seems to be working since you have audio.