Need help to identify smd diode with marking B1

[hrischo192]

Hello,
I need help to identify smd diode with marking B1 on it. I have tried to find it, but without success. The package is the smallest. The board is motherboard of reolink rlc-410 camera, I cannot find datasheet or schematic for that board.
This looks like that, but it is with marking B2 and I am not sure is it same as B1.

I found one 100% good and measured values in diode mode are 1.671v and in other direction is 0.794v

Link deleted - moderator

 

[rjenkinsgb]

Are they against the Ethernet transformer?

If so they are probably surge suppressors rather than normal diodes.

 

[hrischo192]

Thank you for reply. The diodes are connected to transformer, if zoom the picture can see traces and they are on transformer and direct to diode. If it is not normal diode can you send me alternative one, also the values are normal or not. Because on previous post same b1 diode show 1.671v and in other direction is 0.794v, other show 1.015v in both directions.

 

[aliarifat794]

The closest option to my mind is BAS40-05 (Schottky Diode).

 

[rjenkinsgb]

Voltage drop readings with the component in circuit are meaningless, as you are also reading through / across any other connected components.

This is the most likely thing I can find; a bidirectional TVS designed for POE Ethernet port protection:

https://www.mouser.co.uk/ProductDetail/Littelfuse/SMAJ51CA?qs=zHiv0nsVGmo8BzVsH3lW3g%3D%3D

The breakdown voltage is guesswork though, without a full circuit of the device....


The PCB traces show balanced line connections, so they will not be normal one-way conducting diodes.

The PCB tracks from the transformer to those components are also thick, but the visible ones beyond there hair fine pairs.
The implication to me is that those are the high power bidirectional protection parts.

I'd guess there are also connections or diodes on the underside from other transformer pins to the switch mode voltage regulator to the right of that area?