Dell P2416DB - no picture

[YellowJacket]

Hi friends,

I am here for asking for a little help with this monitor. It reacts to pressing the power button, but the only thing I get is working back light, with no picture. I was measuring all power voltages, you can see them in attached picture. There is 3.3V on the SPI ROM chip, and I can see healthy-looking communication on it ( pin 1 is changing ) after powering on. I can see nice clock signal on both crystals. I am even able to measure some low voltage data signals on LDVDS cable. So I believe, my issue in on the panel itself. I proved it by measuring VGH1 signal on a test point and saw, that voltage was initially high enough ( 31.2V ), then it felt down almost to 0V ), VGL1, is all time zero volts, only low negative spike around -1.6V, but it should be around -7V if I am not mistaken.
Now the question is - is it at least partially fixable, like in TV case, where you block some clock signals (SCK)? I have never done it in monitors, since I don't fix them often. There are too many flex cables going to the screen, and I have no idea, how to check faulty "part in the screen", which can I block ( if I ever can ). It is my monitor, so I don't mind, if it won't last too long, just want to save it.

Thank you for any suggestion, and feel free, if you need some additional information/photo/measurement.

[lotas]

Yes, you need to check which side the short is on (where the resistance is lower, the short is there), then remove the resistors on that side and check.

[lotas]

Yes, the problem is in the panel; already two such monitors with the M238DAN01 panel had low resistance at CK(1-8)B1 relative to ground.
Take a photo of the strip (T-CON) on the left and right sides, I will show you where to check.

[YellowJacket]

Thank you lotas (again).

Left and right side atached. I believe, I should check around 0 ohm resistors, right? Resistance to ground is in Mohms on CKxxx though. But there is only 20 ohms on VSTB1 and VSTA1.

[lotas]

Yes, you need to check which side the short is on (where the resistance is lower, the short is there), then remove the resistors on that side and check.

[YellowJacket]

Another solved case thanks to you, Lotas. It works now ( removed all resistors on right side, where was smaller resistance ).
Big thanks to you!

[lotas]

Ok!

[Darkic5]

Hi lotas and YellowJacket, my P2416DB monitor just died during use. The power led lights up, and when powering on it temporarily shows some vague vertical and horizontal lines, after which it turns to complete black.
I checked the voltages YellowJacket described, and they are all identical to your measurements.
After checking the resistors on the panel I find the following values:

Left side: CK1B1 - CK6B1: 7,8M; CK7B1: 8 Ohm; CK8B1: 65 Ohm; VSTB1: 8M
Right side: CK1A1 - CK6A1: 7.8M; CK7A1: 4.4 Ohm; CK8A1: 61 Ohm; VSTA1: 8M

This is my first time fixing a panel, so I don't know what to do now. Are the 4.4 and 8 Ohm values too low? Should I remove all low value resistors (on both sides), or just the 4.4 Ohm? After removing, should I power it on in this state? Any way to fix the short, or are these shorts in the panel itself?

Please let me know if I should check anything additional. Hope I can save this screen to use it a little longer!

[lotas]

Remove resistors only from one side, where the resistance is lower. Yes, this short circuit occurs in the panel itself.

[Darkic5]

Thanks so much lotas! I removed both the 4.4 and 61 Ohm resistors on the right side, and now all resistors on the left show 4.7 to 4.8 MOhms. It works again now! Although, I have no clue how and why. Can you direct me to a source where this is explained perhaps?

[lotas]

The panel is divided into left and right parts and these signals are duplicated for each half, you had a short circuit in the panel on one part and when power was applied T-con blocked the supply voltage to the panel, after removing the jumpers (resistors with zero resistance) the short circuit disappeared and the voltage recovered and began to work from one half.