Humminbird 385CI - switching diode SOT-23

[Travis79]

Hi there!
I wonder if here is anybody who could give me a hand with my issue.
I'm trying to repair my Humminbird 385CI fish finder.
Beside the SA604A replacement, I discovered that switching diode has been blown/burned.
The question is quite simple. How can I define what switching diode it was?
The only information I got from Humminbird support is that it is switching diode and it is SOT-23 form factor.
It is located directly on the Vcc path, right on the input path from the battery.
I assume it functions as a fuse, right?
The technical specification of the unit says, that its current draw is 425mA.
I'm desperately looking for the switching diode with forward current around 500mA, but having no luck. Mostly they are rated 250 mA max.
Am I looking for the wrong rating of the diode or is it really so hard to find such diode?
Does it mean that the switching diode doesn't have be rated >250 mA with such unit current draw?
Unfortunately I was not able to get schematic of the board
I'm attaching picture to show the reality at least.
I'll appreciate any advice.
Thanks!

[fzabkar]

It looks like a reverse polarity protection diode, probably Schottky. It doesn't appear to have any switching function.

I would just use any Schottky diode that fits, even a 2-pin type. Diodes which are rated for higher currents will have a lower voltage drop.

That said, I would be concerned about possible damage downstream of the diode.

Edit: Maybe I'm wrong, but could the diode be a back-EMF protection diode connected across the primary winding of T401?

[Travis79]

Hi fzabkar,
Thanks for your thoughts.
My initial idea was to replace it by Schotkky diode as well, but I decide to ask others for their opinions as well as it is an issue I don't understand exactly but would like to
If I did the measuring correctly, the diode is in series only. No parallel connections to it.
It shares the two pins on one side and outputs one to the other side.
If I would like to replace is by the "original", did you see any with proper parameters anywhere around?
Cheers, Travis

[fzabkar]

Could you show us the other side of the PCB?

[Travis79]

Sure, but as one can expect, the PCB is multilayered

[fzabkar]

Sorry, I can't make out where the diode goes.

If it's in series with the Vcc supply, then it would be a common cathode, dual diode, not necessarily a switching type. If it is a back-EMF snubber diode connected across the transformer primary, then it would be a dual, common anode, switching type (with a lower current spec).

In either case I would still be concerned about damage to other nearby components.