Vizio LP2626/VMM26-F20I

[sportsman99]

Hello, New to forum, i have a vizio LP2626 monitor, my boss gave me because it is broke and warranty wont fix it. so at first when it powered up it would say no signal. after tinkering around the boards, i replaced c503 and c504 it now will show a hdmi picture for 3 seconds then go black. any suggestions. thanks,

[tom66]

Re: Vizio LP2626/VMM26-F20I

Pictures of the boards will be essential, good, clear in focus.

Sounds a lot like "2 secs to black", possibly dead inverter/CCFL. Presumably it just stopped working some day? In which case it might just be bad caps...

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

I have uploaded 3 pictures, could you give me some info of repairing the CCFL?

thanks,

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

Is there anyone that can elaborate on this CCFL dead inverter. thanks,

[PlainBill]

Re: Vizio LP2626/VMM26-F20I

Is there anyone that can elaborate on this CCFL dead inverter. thanks,

Well, the inverter isn't dead. It may be shutting down because of a defective CCFL. Note the 4 connectors at the top of the first picture. The wires to the CCFLs plug into those. There are two methods of testing.

1. Unplug the monitor CCFL from connector 1. Plug in a test CCFL. Turn on the monitor. Does the test CCFL light? If 'No', the inverter output is bad. After lighting, does the test CCFL stay on? If no, the output is probably good, and the monitor CCFL connected to it is probably good. Now unplug the test CCFL and plug in the CCFL lead normally connected to connector 1. Repeat for connectors 2, 3, and 4. You are looking for two things.
A: A connector that will not light the test CCFL, or for which the test CCFL is noticeably dimmer. That indicates a bad transformer or other problem.
B: A connector that when the test CCFL is connected the backlights stay on. The CCFL normally connected to that connector or the wires to the CCFL are bad.

2. Unplug all CCFL leads except one. Turn on the monitor. Is there a flash from the screen? If no, that transformer or CCFL is probably bad. Disconnect that CCFL, and plug the next one into it's connector. Turn on the monitor. Is there a flash on the screen? Continue plugging in one CCFL at a time. Some designs have the transformer between the two CCFLS. In that case, you must plug two CCFLs into a pair of connectors.
The object is to identify one CCFL or one output that will not cause a flash.

PlainBill

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

Is there anyone with a schematic or an ole board laying around they could verify the placement of caps c503,c504,c517 and c519. the power supply fits a lp2626 board # VMM26-F20I, the two different cap numbers are n3-3kv-sec and 12J-3kv-jnc,, thanks so much!

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

I do not have a spare ccfl, i tried removing one pair of connectors from the power unit( blue/black and pink/white) and also tried all disconnected except for one at a time. no flash from any scenario, every time the unit does the exact same response, unit comes on wait 4 seconds picture shows for 2 seconds then black screen again. i also have a vw32l im trying to fix, but obviously no parts are interchangeable. i have replaced c504, i really need to buy a esr meter, but currently dont have one. i would say the ccfl is okay, i read in another forum that the ccfl is not signaling back to the supply so there fore it shuts down. any advice would be very helpful. thanks,

[PlainBill]

Re: Vizio LP2626/VMM26-F20I

We seem to say this several times a day. The very best advice we can give is to supply several pictures. Each picture should be as close to 2000 x 2000 pixels without exceeding that size. One picture should be of the top of the power supply, one of the bottom.

In most cases the control signals for the inverter are strictly one-way. The signal card turns on the inverter and sets the brightness. If the inverter encounters a fault condition and shuts down, the signal card does not know about it. I HAVE helped troubleshoot failures of the protection circuitry on inverters. It is very tedious.

PlainBill

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

what would you need pictures of and ill be glad to upload them. would i be time ahead to just purchase a inverter ckt? i would be glad to trouble shoot, with your assistance. i do have a o'scope and familiar with using one. oddly enough, i dont have a schematic of this tv or any tv and i do not know what or how much of this is the inverter ckt. this monitor was given to me from my boss and it is of great desire to fix this unit, especially if i could fix at the component level. your assistance would be very much appreciated.

thanks,

[PlainBill]

Re: Vizio LP2626/VMM26-F20I

what would you need pictures of and ill be glad to upload them. would i be time ahead to just purchase a inverter ckt? i would be glad to trouble shoot, with your assistance. i do have a o'scope and familiar with using one. oddly enough, i dont have a schematic of this tv or any tv and i do not know what or how much of this is the inverter ckt. this monitor was given to me from my boss and it is of great desire to fix this unit, especially if i could fix at the component level. your assistance would be very much appreciated.

thanks,

A picture of the bottom of the power supply might give us the information to help you. Without it, I can't help.

PlainBill

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

here you go thanks,

[PlainBill]

Re: Vizio LP2626/VMM26-F20I

here you go thanks,

I was rereading an earlier post. Please verify that even if only one CCFL is connected, the display comes on for two seconds and then goes black.

Also, we seem to have missed a troubleshooting step or three. After the display goes black, have you tried shining a flashlight on the screen at an angle? Can you see the desktop (or whatever was being displayed)?

If you can't, one additional step is necessary. I've marked up your latest picture. In the lower left corner I have circled two pins in teal. I believe these are the control signals for the inverter. Check the voltages on these pins when the screen is on, and again when it goes black. If the voltages do not change, you have 'two seconds to black'. Report those voltages.

And the last steps. I've circled two pins in the upper left corner in yellow. What is the resistance between those pins? And also, there are two pins circled in red in the upper right corner. What is the resistance between those?

Aww, crud. I just examined the picture of the top of the power supply carefully. Between the two heat sinks is a greenish cap. What brand is that?

PlainBill

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

the resistance between the yellow circles is 436 ohms on a digital meter.
the resistance between the red circles is 436 ohms on a digital meter.

the voltage at the teal circles the one to the outside is 5v ~ 4.96v
the voltage to the second teal circle to the inside is 2.9v

i did not see a voltage change during picture to black screen.

i did not see a picture with a flashlight.

the capacitor is a samxon 680 micro F 16v.

thanks,

[PlainBill]

Re: Vizio LP2626/VMM26-F20I

the resistance between the yellow circles is 436 ohms on a digital meter.
the resistance between the red circles is 436 ohms on a digital meter.

the voltage at the teal circles the one to the outside is 5v ~ 4.96v
the voltage to the second teal circle to the inside is 2.9v

i did not see a voltage change during picture to black screen.

i did not see a picture with a flashlight.

the capacitor is a samxon 680 micro F 16v.

thanks,

The transformers are most likely good.

the fact that the voltages do not change indicates this IS a case of 'two seconds to black.' The flashlight test is not definitive - I've never been able to get it to work.

By any chance are the letters 'GF' on any of the caps? Something about green SamXon are a known bad series....

PlainBill

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

it has GK(M) then Y2A then 105o CH

[PlainBill]

Re: Vizio LP2626/VMM26-F20I

it has GK(M) then Y2A then 105o CH

OK, that should not be a problem.

PlainBill

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

any other suggestions?

[PlainBill]

Re: Vizio LP2626/VMM26-F20I

any other suggestions?

I see several options.

1. Since you don't have a spare CCFL, it has been reported that a small (.01uF?) or about a 120K 5 watt resistor will serve as a dummy CCFL.

2. Recap the power supply / inverter.

3. Disassemble the LCD panel so you can visually examine the CCFLs.

I'd start by recapping the power supply / inverter card. If you fixed one problem by replacing a couple of caps, there is no reason to believe the remaining ones are any better. On the same order I'd buy a 120K resistor.

Or you can scrounge around and see if you can find a dead LCD monitor at a reasonable price (as in Free).

PlainBill

[sportsman99]

Re: Vizio LP2626/VMM26-F20I

Well recap of the power supply hasn't helped.
I disassembled the lcd panel, not sure what to look at of the ccfl's but all looked clean to me. i believe i have some 5w 120K resistors, could you explain where and how to use them, i would think you are inserting across the pink and blue connectors in place of lcd, then supply i'm guessing should stayed power up as in working state.

i noticed with the main board and power/inverter laying on my desk with no ccfl connected that i dont read any voltage at U301 or Drain of Q301 possibly due to TV disassembled and not turned on.

is there any way to test the inverter by itself. no main board or ccfl connected?

thanks, thanks, thanks,

[PlainBill]

Re: Vizio LP2626/VMM26-F20I

Yes, use the resistor as a substitute for a CCFL. Check each output and see if the backlights stay on when one CCFL is replaced.

PlainBill