Powerline Network Adapter power Issue

[pintglass]

Hi
Im trying to repair a D-Link(DHP-300AV) powerline adapter which is not powering up.

I've only done some basic tests at the moment to confirm its getting mains in through the fuse which it is. All caps dont show any sign of buldging.
The power supply seems to be based around a LNK623PG as can be seen in the images attached.

Can anyone provide any trouble shooting steps to try and diganose whats causing the no power issue.

[Per Hansson]

You can look at the datasheet of the LNK623PG to get an idea.
But with these units running as hot as they usually do they often bake the capacitors.
So just replacing them without much other tests might be worth it.
Or just throw it is the trash: I hate these devices with a passion.
They pollute the radio spectrum so much that even regular FM broadcasts are affected.
Nevermind AM or short wave, I never understood how these get FCC approval!

[pintglass]

I agree I should just throw this away, but my curiousity gets the better of me at times.
Just out of interest on page 4 of the datasheet for the LNK623 it shows a reference design schematic with the feedback winding on the secondary side of the transformer but in the output regulation section of text it says
"The output voltage is sensed using a primary referenced winding on transformer T1 eliminating the need for an optocoupler and a secondary sense circuit"
Does this mean the reference is on the primary side?

I've attached the page of the datasheet for reference.

[Per Hansson]

No it means it can perform regulation without any "real" (expensive) sense logic.
But you do have an optocoupler on your device (U8) so might not follow the reference design.
That said I was unable to trace where it goes so maybe it is for something else.
In your seat I would replace the caps, Acon is a shit brand and it would not be uncommon for them to fail.
But if you want to do some checks just see what output voltage you have on the LNK chip, and on the caps and see if it makes sense.

[budm]

https://www.badcaps.net/forum/attach...8&d=1597579006

Did you check resistor R5 (624) to see if its resistance has gone up?
That resistor and the Diode PD8 look to be for Brown protection that will shutdown the LNK via OPTO.

[pintglass]

Originally Posted by budm

https://www.badcaps.net/forum/attach...8&d=1597579006

Did you check resistor R5 (624) to see if its resistance has gone up?
That resistor and the Diode PD8 look to be for Brown protection that will shutdown the LNK via OPTO.

I've checked the resistor and it seems fine giving a reading of 619 K ohm's