Shorted Cap Near m92 and MAX77620

I wanted to get a second opinion.
Nintendo switch black screen draws 300ma plugged into the charger, no signs of lifeeeee :cold_sweat:
I have a shorted cap under the m92 chip I took the chip off, took off the pi3usb and bq chip, and it’s still shorted. :face_with_head_bandage:
Removed the cap and the line is still shorted.
Checked the big cap above the pi3usb ic and it’s not shorted.


also, the enxx chip inst giving the 3.3v on the output which I’m assuming is due to this line being shorted.
I then checked the MAX77620 and the cap on the top right is shorted does this mean this chip is bad possibly?
shortted cap above 776

also, does anybody have any diode mode pictures for the MAX77620? having a hard time finding a picture.

The ENXX ic won’t produce the 3.3v without a certain rail from the Max77620A so don’t worry about that for now.

You have a short on the 1v8 rail assuming you mean the top of that cap is shorted, that rail goes to many places on the board and with 0.33a draw there may be a good amount of heat being generated by the shorted component so search around for it.

You probably should have attempted to find the short before plugging in the power

Unplug the nand module from the board and see if the short clears, use ~100c hot air for a few seconds to soften the glue holding the nand ic to the wifi shield, be gentle when removing it, it is a BGA component and bends easily

Also make sure the port is in good condition before plugging in a usb on a switch, the port should always be examined before applying power

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really appreciate the picture!! i owe you one.
Just an update:

checked verified using the above image that its off by alot, i dont have my stencils yet so i reflowed the MAX77620 and boom that cap below the m92 is no longer shorted and that one cap above the max is no longer shorted also, and now i have a shorted sys line WAIT, while writing this i gave the max a lil nudge with no heat and sys is no longer shorted LOL, but everything on the left of that picture the inductor and cap in between is giving a short to ground with a diode reading of 0.011 (should all be 70s in diode mode)

So next plan is to wait for my stencils to come in and reball it throw it on and check the readings again.

Again really appreciate the help, as im pretty new to fixing electronics

Alright update, stencil came in reballed the max chip and boom reading looked better but one area is still shorted. i can going to trace the line using Switch erista board layers and see what i can find, image below of what is still shorted

MARIKO board has less than 20 ohm on that 0.8v line, how much resistance there you call it short?

i get about 15 ohm on that side, board is a HAD-CPU-10 and my max chip has a H at the end.

exactly, v2 board I got mine at 16.8 ohm on that line. So thats not a short.

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Oh snap!!! Thank you, love you jkyoho, im am now going to try to boot into os.

I think i have bad news, i injected voltage using 1 wire on the usb-c port and 1 wire on the coil next to the BQ chip and it reads 0.7xx amps at 4 volts, Max gets hot as helllllll also the cpu gets warmer than the areas around it? Need some advice should make it a parts board or go for the cpu re-ball?

what where why

how much current draw from charge port without battery plugin

I got this board in pretty bad shape, the shield over the CPU looks a lil brown so I’m suspecting someone tried to maybe reflow or reballed the ram, right now there is no usb-c port so I can’t check what the amperage would be, I can throw one on in the morning and check

I took off I took off the shield and this is what I found :sob: it looks hella crispy

definitely been BBQ both APU and RAM. Donor Board pile confirmed

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i ordered a cpu stencil, i am going to try to reball it and see i can get any improvement. for fun lol

SoC looks fine and doesn’t seem as though it’s been reworked, the flux around is is likely just because it’s wicked up the shield by the person who did the Ram reflow.

If your going to proceed I’d first determine if you have a short on your SYS rail and if yes identify that first (you should also check all your other primary rails too ie: check the resistance to ground) by the sounds of it it’s the Max IC which is responsible (though it’s not clear which one your referring to?) , if/when you resolve that issue then proceed by reballing the Ram. Given the SoC is getting hot it’s entirely possible it’s dead already :man_shrugging:

For future reference you shouldn’t be applying voltage willy nilly to seemingly shorted rails (at least not at this stage at these voltages) rail could potentially not be enabled ordinarily as a result of OCP/short circuit protection which might prevent damage downstream (for example a short from your SYS rail to a CPU line for example) which could possibly save it (this is just an example mind you) in which case you’ve just bypassed this and killed it yourself (again, just an example, you might not have)

You might want to take photos of the board front and back for your reference later (incase liquid damae, clues etc) .then Ultrasonic the board as it’s in desperate need of a bath

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with no emmc its pulling a little above 1 amp.

I checked everything and everything looked good the only thing i found shorted was that cpu cap below the m92 and that one cap above MAX77620H, after reballing the MAX77620H the shorts were gone.

it shouldn’t be, it’s implying you have something else shorted which shouldn’t be. check your other rails. I presume this is via USB? (you should probably avoid plugging this board in/connecting battery in it’s current state anyway)

It’s not a CPU cap, it’s 1V8PDR/ pretty well everything is connected to this rail.

Was this PMIC poorly reworked prior like the Ram?

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MY BAD! its pulling 0.1 amps

Sorry about that new to fixing electronics so i can only reference it as what I’ve seen the most referred to (cpu cap LOL).

Yea it looks like the previous owner Re-balling the PMIC or maybe they just reflowed it? was poorly done due to after my attempt reball the short 1v8 short was gone on those caps and everything checks out now, worried that this short might have killed the soc or ram especially after injecting that voltage.

So far my next steps is to reball the ram, and if that doesnt work make it parts board :cold_sweat: . Really demotivating i thought i could save this one.