grandstream ip camera gxv3611_hd poe circuit

[cashkennedy]

I have a bunch of these grandstream ip cameras that fail after 2-3 years of use for poe. Supplying them with 12v power instead of POE works, but id like to fix the poe portion.

Im hoping the 63v 47uF capacitor (c37) is the issue. I assume that cap filters the incoming POE which is usually 48V. Since using 12v works I assume all the 16v caps are still okay (im sure yall would replace them all anyways). There is also a 100v 10uf capacitor (c39), which im not sure what it does, perhaps a startup capacitor for the chip that handles negotiating the poe power and converting the poe 48v to 12v?

The 20 pin IC on back of poe area is tps23750
https://www.ti.com/product/TPS23750
https://www.ti.com/lit/gpn/tps23750

[cashkennedy]

Re: grandstream ip camera gxv3611_hd poe circuit

Unrelated to diagnosis:

I think its interesting that even in the manual for some of the grandstream IP cameras they put this:
A few parts (e.g. electrolytic capacitor) of the equipment shall be replaced regularly according to their average life time. The average life time varies from the differences between operating environments and usage history. Regular maintenance checks are recommended for all users. Please contact your dealer for more details. Though I cant imagine any dealer is sending these cheap cameras anywhere to get the capacitors replaced. The 30 mins it would take per camera and shipping would be almost half the price of the camera.

One of the engineers at the company also recently posted that they cant rush cameras to the market cause they usually end up with crap hardware / longevity. So I guess they know of the problem but only care so much...

[cashkennedy]

Re: grandstream ip camera gxv3611_hd poe circuit

From what I can tell they stuck pretty closely to the isolated flyback design in the poe controller's datasheet. Ive attached a picture of part of that design.

C37 on the camera appears to be C4 on the reference design.
C39 on the camera (100v 10uf capacitor ) appears to either be c1 or c2 on the reference design.
The inductor right next to C39 on the camera is marked L3 on the board, and 100 on the part. I would assume that is L1 in the reference design. Perhaps the larger inductor and larger 100v cap is because the camera converts poe to 12v not 5v as in the reference design, and perhaps they wanted more ripple control? Is the purpose of the inductor and capacitors after the inductor to minimize ripple?