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Old 01-25-2019, 01:43 AM   #21
misteeka
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Default Re: Dell U2413 turning off

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!
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Old 02-01-2019, 05:58 PM   #22
djatila666
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Default Re: Dell U2413 turning off

Hi misteeka
My monitor is working good. Look the image.
That is my repair.
Attached Images
File Type: jpg Dell.jpg (133.3 KB, 62 views)
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Old 06-12-2019, 11:39 PM   #23
gamexciter
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Default Re: Dell U2413 turning off

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
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Old 07-17-2019, 07:54 PM   #24
slashgeegee
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Default Re: Dell U2413 turning off

check the capacitor if theres a leakage
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Old 10-28-2019, 02:34 AM   #25
gaijin4life
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Default Re: Dell U2413 turning off

Quote:
Originally Posted by gamexciter View Post
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.

Last edited by gaijin4life; 10-28-2019 at 02:40 AM..
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Old 10-28-2019, 07:07 PM   #26
gaijin4life
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Default Re: Dell U2413 turning off

Quote:
Originally Posted by gaijin4life View Post
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...
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Old 11-15-2019, 10:58 PM   #27
gaijin4life
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Default Re: Dell U2413 turning off

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.

Iíve 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 donít have any of the legs touch - DO NOT HAVE THEM TOUCHING EACH OTHER AT ANY POINT), but thatís 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.
Attached Images
File Type: jpg q971.jpg (783.7 KB, 1 views)
File Type: jpg q972.jpg (563.5 KB, 1 views)
File Type: jpg thyristor.jpg (512.1 KB, 1 views)
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