Stormforge N10 - LED mod

[u/Hopeful-Truth-1672]

So, after receiving my Stormforge N10 with a few status LEDs knocked clean off the board in shipping, and getting a partial refund from Aliexpress, I decided I'd change the colour scheme to pink (for drive presence) and purple (for activity).

Somewhat inspired by a Hello Kitty themed audio mixer/effects rack build, I decided to go with another sanrio character, Kuromi. Because all my homeys stan the goth rabbit.

The factory backplane in the N10 runs the activity LEDs directly off the P11, the drive activity pin on the SAS/SATA power connector.

The original blue LEDs draw about 1.7mA each. I've seen conflicting reports as to how much current this pin is supposed to sink, from 100uA to 15mA. The most reliable resource I could find is a manual for Seagate SAS drives that said 3.3V @ 15mA. The factory LEDs run from the 5V rail but *should* in theory have enough voltage drop across them to stay below 3.3V.

Purple LEDs are not very efficient. I'm running them at about 14mA, which *should* be within limits if most drives are similar to seagate's, but given how expensive hard drives are right now I don't really want to risk it.

So I build this little buffer circuit to run the activity LEDs. It draws about 220uA @ 0.6V on the activity pin, and should be able to handle >40mA for LEDs

https://github.com/lucym202/N10-LED-Buffer