Dell se2419h monitor

[MarkBob]

Hi

I have 2 of te above mentioned monitors with the same fault.The power button is lit but when pressing to switch on no logo nor screen come to life .Tested all electro -caps all seem fine.No power to backlights.Please i am stumped 

[RayRay]

How exactly did you test the capacitors? Also, Do any of em have a bulged (non-flat) top? Have you checked the fuses & diodes?

[MarkBob]

Hi

Removed all caps and tested caps on both psu s replacing 1 board with new caps ,other board with tested and checked all the diodes on both. I get standby power and 24 v on 2 pins and no other voltage. The backlight output has 0v .On the video board i replaced 2 caps still no change.

[RayRay]

Could you provide pictures of the board (from both sides)?

[perieanuo]

Hi

Removed all caps and tested caps on both psu s replacing 1 board with new caps ,other board with tested and checked all the diodes on both. I get standby power and 24 v on 2 pins and no other voltage. The backlight output has 0v .On the video board i replaced 2 caps still no change.

yep, you got a problem: no 5V or 3.3V present
usually you have 5V standby voltage that powers some micro monitoring the buttons, to put it simple
no 5V, no micro working
either you missed those 5V either the 5V regulator is dead, gotta dig this standby voltage, it's a classic even for pc supplies, tv's and other equipment.
try to trace that missing voltage, maybe on 5V rail you have a short (any component hot?)
regards,pierre

[MarkBob]

Here are the pics

[MarkBob]

Does anyone have a schematic diagram as i am unable to source one 

[RayRay]

Couldn't find a service manual for this particualr model. Anyhow, I assume you've only tested the diodes on the brown side? Did you test em in both forward & reverse bias? You're not suppose to get a reading in reverse bias FYI. Also, what about testing the resistors & ceramic capacitors? Try to wiggle the white connectors a bit (to see if they're loose), they might require a reflow. And just so you know, this board is available from multiple sellers (at affordable prices) on ebay:
https://www.ebay.com/itm/114663964073
https://www.ebay.com/itm/133602634051
So if nothing goes, you have the option of just replacing em.

[MarkBob]

Hi

Thanks so much i shall test on the other side .......i just find it strange that both monitors have the same fault

[RayRay]

You're very welcome. And yes, it's indeed quite strange, which brings me to the following question: Were you using each monitor with a different computer, or both with the same one (in a dual monitor setup)? If the 2nd, it's possible the problem is with your computer (and not the monitors). Just putting that possibility out there.

[MarkBob]

Hi

Different desktops but in the same office .I shall check the resistors as they are fuseable arent they. All the diodes i checked in rev bios and they checked out fine.Ordering via ebay and shipping is so costly to where i am its probably cheaper to go the new Route which unfortunately i ust cant do

Thanks so much in advance

Ray- Ray
 

[perieanuo]

your smps creates 2 voltages: one that goes to the connector with wires and a second one (D633?) which powers the smd chip with soic16 case
you measured the second one? that one should be 5V for standby control

[MarkBob]

I shall check that out .....

Thanks so much

[MarkBob]

Hi perieanuo


On the second voltage i get 7.5v

On the back of the voltage regulator i get 7.2v


I have no clue as to why the voltage is so

i guess i will have to find a recycled set of boards 

[perieanuo]

the soic 8 chip code is?
i doubt 7.5V is ok for voltage regulator chip that powers the soic8 ic.
it's obvious the 7v5 is the source voltage for the 5V (or 3v3 who knows..., that's why i ask about the soic8)
[edit]
well, it's already june, i give up this one