I believe I have damaged my Scarlett 6i6 2nd Gen recording interface hardware unit by mistakenly, briefly using the power supply for another device. The incorrect power supply was plugged in for a few minutes before I removed it and connected the correct power supply. Can I fix the damage caused?

I opened the unit and examined the circuit board, and everything looks intact. There are no obviously damaged circuits, nothing fried or weathered. The incorrect power supply was a 21.5v DC 370 mA output, 100-240VV AC 60Hz input AC-DC adapter, and the 6i6's unit's proper power supply is a 12V 1200 mA output, 100-240V 50/60Hz 0.5A input Switching Adapter. Both power supplies' inputs are 100-240V. Thank you.

Can you post a good picture of the PCB?

Thanks for the reply. See attached. Hopefully these will do.

Can you do one more and focus in on the PCB where power supply jack is? I'm trying to see any type of micro fuse. Also, does/will this unit run off buss power? Sorry I just couldnt zoom in on that area with that pic.

See below.

Well lets try again. We need some of the circuitry in the pic. How about an area, say 4 inches by 4 inches. lets see what that will show. This pic doesnt show any components that we need to look at. Something like this area.

Why do you believe you damaged it? I know HOW you think you damaged it...But you haven't reported any issues with the unit.

Is it no longer powering up? Is it not passing audio?

What symptoms are you experiencing (if any)?

See below. Thank you again for your help ?

It’s no longer powering up.

Were the polarity the same on both PSU? Do you know how to use a DDM/Digital Multi Meter? I circled (in red) U9, I cant see the codes/part number. look it up and see what it is.

Yes, the polarity is the same on both PSUs: - o +

I do not know how to use a DMM/Digital Multi Meter, but I can learn. I believe the codes/part number on U9 is 7UGB 244. I've attached an image where I circled (in red) what appears to be U9. I do not see an image with your reply where you circled (in red) U9.

youre right about that pic...., I may have posted it in an other thread

can you post a close-up of that chip? kind of hard to see.

Do you have a DMM/Meter? as for U9 if thats all it has on it (7UGB 244) thats inhouse. If youve a meter you can check a few places, see if youre getting voltages/readings and where.

I do not have a DMM/Meter. Can you recommend one that is reliable and a good price? As for U9, besides "7UGB 244." it has a dot and a line above that as you can see.

Once I use a DMM/Meter to check a few places and see if I'm getting voltages/readings, what do you think will be the solution if I'm not getting voltages/readings or if they're not as expected.

email focusrite support, and see if they'll tell you what IC (U9) is. I couldnt come up with anything.

You should be able to get a good one for $40.00, couldnt really make a recommendation. I use Flukes, and an Rigol DS7034 Digital Oscilloscope. I've a couple burners/DMM cheap and analog meter. When you get one, youll notice whats called (Vias) the through holes. You'll see some that have TP (test points) and a number, and maybe a test voltage, we can test those, first test the power supply, always wise, then test the TP's see how and if they read, may need to start at the jack. If worst comes to worst though...., you will be learning something you can fallback on, in the furture.

I will order a DMM and start testing. I will also email Focusrite support and ask them what IC U9 is. Thank you for your help. I will certainly learn something through this process.

Hey, I dont mind. It would be nice to know what IC U9 is. Ask if they have a data sheet on it and any other IC's (chips) they may allow.

When you contact Focusrite, explain what happened and ask if they have a flat rate for repairs or if it's a bench fee to just look at it and then parts/labor hours added on. You'll probably foot the bill for shipping. I'm inclined to think they won't tell you what IC U9 is and if they do, not sure they would sell it to you. You might also ask if they could provide a service manual or at the very least a schematic.
I commend you for wanting to try and repair it yourself, but I'm afraid without some reference to what voltages you might expect to measure and some knowledge of what the circuit is doing, you likely can't be sure where the problem really lies. Even if you think you know what component(s) may be faulty, removal and resoldering a new component in could be challenging if you've not done this kind of work with SMT components.
The DMM you buy is worth having and a good investment. Buy a label maker for your marking your power adapters

If it just wont power on, it is probably, as Rick alluded to earlier, a fuse.

With the pic oriented as-is, see the blue and brown wires with the red jackets? There should be a fuse around there somewhere; you might need to pull those connectors off to get to it.

Blue and brown wires have crimp-on spade connectors to connect to the power switch... no fuses would be physically located in those wires.

However on the PCB there is an SMT component which 'might' be a fuse (or a semiconductor in the power supply path). The blue and brown wires may hiding adjacent nomenclature that may give a hint to the type of part. If a fuse, it may be a variation on those shown in image below. If a semiconductor, I'll guess U9 may be an IC that provides control to it for regulation of voltage and circuit protection.
If the OP could move the blue and brown wires and get another pic it may help to identify the 'block' component.

Again, removal and resoldering components that are SMT could be a real challenge for someone not experienced at doing it and could result in damage to the circuit traces if proper care isn't taken.

Not IN the wires, but in the black "box" the wires are connected to?

Heres another pic of that 'block' component. It's an 6i6 PCB, but it has to be a different Gen, as this one is offset. There's just not any pic's of the 6i6 PCB on the interweb. Also heres a pic of the bottom of the OP's board. I circled the power jack lugs and the pins to the switch connector. But yeah, that block component looks interesting.

I just got an 18i8 that didn't power on, presumably as a result of a similar mistake. Looks like the design of the 18i8 is quite similar to the 6i6. Symptom is that the "+V" (input) rail was shorted to ground, causing the AC adapter to go into overcurrent protect mode. I traced the problem to a zener diode that had failed short, D23 on the 18i8 (seems to be a 15V zener diode, marked PH C15). Removing the diode neuters the overvoltage protection, but enables the unit to power on. Not sure what the label for that diode is on the 6i6, but it looks like the zener in question is basically directly under the power switch, near the edge of the board.

Some other notes that others might find useful:

The DC to DC converters are all made by MPS. U8 (+48V) and U25 (+6V9 and -6V9) are MPQ3425 and are marked MPGC 3425 388. U41 (+3V3) was harder to track down (had to look up parts on digikey and look at datasheets to compare against how the chips on the board are actually wired up), but it appears to be MP2227. The important part of the marking for MP2227 is the "7U", the full marking on mine is 7UGB 244, but presumably the GB and 244 refer to date codes, lot codes, etc. and likely can vary from device to device. Looks like on the 6i6, +3v3 is provided by U9, also an MP2227. The other two converters look very similar in how they're wired up, so they're probably also the same design - an inverting topology for -6v9 and a boost topology for +48v, both likely using the MPQ3425.

The bipolar +6v9/-6v9 is actually rather interesting. There isn't an example schematic for that in the MPQ3425 datasheet; I might have to trace it out and figure out how it works. The +48v supply looks like the +48v design from the MPQ3425 datasheet, followed by a CLC filter.

Also, that black box near the power switch connector is a common mode choke. It's marked L21 on the 18i8; none of the pictures of the 6i6 show the label.

Hi Aj, sorry this happened to you.. But, I'm very interested to see where this thread goes as I have the same model 6i6 2nd gen as you, and have every reason to believe something in my power section went caput. I may open mine back up and see it there are any fuses. I did look for voltages across all the electrolytic caps and none where there so, something is happening very early in the power stage.

Good luck, I'll let you know what I find also if I think it could help.
Best,
Phil D.