Dell U2413 turning off

[misteeka]

Hi djatila666,

I just bought a refurbished unit of this monitor and have the same problem. I'm glad I found your post and this forum. Is your monitor still stable now more than 2 months after your last post?

If so, I'm tempted to try the same fix (versus returning my unit to the dealer and dealing with shipping etc).

What was the process involved in applying new thermal paste to K15A60U? Is there a recommended method to remove the heatsink (is there any best practice I should be aware of)?

And is adding the radiator to LD7904jgp7 as straightforward as it sounds? I can look up how to do this, I assume also with some application of thermal paste etc.

Thanks in advance for any help and for your contribution to this thread!

[djatila666]

Hi misteeka
My monitor is working good. Look the image.
That is my repair.

[gamexciter]

I got the same problem.

- Standby power (5V) still on
- PS1 (24V): 0V

Already replaced some following components: 03 schottky diodes (SRF 30-10) + 1 opto coupler at Main Switched PS; IC LD7904JGPN; MOSFET K15A60D at FPC area; 02 MOSFETs K10A60D closely to the main transformer. Nothing changes.

When used a laptop CPU cooling fan and directed the air flow to the main switched PS area, the screen turned on in 3 seconds.

I used a meter to check the value of components around the PFC and main switched PS areas. All components seem to be still in good condition.

Thanks for any help

[slashgeegee]

check the capacitor if theres a leakage

[gaijin4life]

Originally Posted by gamexciter

I got the same problem.

- Standby power (5V) still on
- PS1 (24V): 0V

Already replaced some following components: 03 schottky diodes (SRF 30-10) + 1 opto coupler at Main Switched PS; IC LD7904JGPN; MOSFET K15A60D at FPC area; 02 MOSFETs K10A60D closely to the main transformer. Nothing changes.

When used a laptop CPU cooling fan and directed the air flow to the main switched PS area, the screen turned on in 3 seconds.

I used a meter to check the value of components around the PFC and main switched PS areas. All components seem to be still in good condition.

Thanks for any help

Q971 and Q971 are likely the problem. Gated thyristors that have become too sensistive.

[gaijin4life]

Originally Posted by gaijin4life

Q971 and Q971 are likely the problem. Gated thyristors that have become too sensistive.

Meant to say Q971 and Q972. Won't let me edit...

[gaijin4life]

So replacing the two thyristors are the answer for this problem. Q971 and Q972. Unforunately the original MCR part had a non-standard arrangement of Gate, Anode, Cathode (K) leads, and there are none I could find with the correct order, so you MUST bend the pins to have the right one go to the correct hole on the board, changing the Littlefuse Thyristor from KGA pin order to GAK order to match the original part - you CANNOT use the default arrangement.

The replacement part you want is Littelfuse S4X8ES2, and mouser.com has them for a 45 cents each - the $7.99 shipping will be the most expensive part of this. I ordered 4 since they were so cheap so I had spares in case I accidentally broke a pin in the bending.

The data sheet for the part is here: https://www.mouser.com/datasheet/2/2...pdf-319336.pdf

To open the case on your Dell U2413, I highly recommend the ifixit kit with the guitar pick things (or actual guitar picks). They get the case open without marring it.

I’ve attached a few pictures showing where the parts are on the power supply board in the monitor and also how to bend the pins of the replacement thyristor so it has them in the correct order when you solder it onto the board. This will stick up a lot higher than the original due to the bending (so you don’t have any of the legs touch - DO NOT HAVE THEM TOUCHING EACH OTHER AT ANY POINT), but that’s no problem.

Thank you Dell for cheaping out on parts, cutting another corner that your customers have to figure out to avoid throwing a perfectly good monitor away.

[qwec01]

I have similar problem, black screen, backlight off, power led off, 3 USB ports have 5V, the one with lightning sign dosen't, and I can't turn it on, after 3mins, it will turn on automaticaly, looks like an overheat problem.
The monitor will turn off quicker when it's 100% brightness compared to 30%, when the monitor shuts down, I measured standby voltage, it's 5.0-5.2V and not steady, the ps-on signal is below 3.3V and jumping around, the wierd thing is the 24V is present and steady.
I don't know if replacing Q971 and Q972 will work, need help, Thanks!