MAX77620A Diagnosis and replacement

I have a board invthe same state, missing 1.35v other rails missing. Resistance on 1.35 rail looks good in the 3m range. I will probably swap out the pmic when i get a chance. When i do i will try ans update here.

That would be great! Looking forward to good news man

Pretty much all the rails produced by the PMIC follow a sequence and one thing has to be true (or the thing before) before said rail/s are enabled. Unfortunately without a datasheet this is hard to be sure of, but I believe this rail is enabled directly by the SoC and again, unfortunately, any number of things can prevent htis rail from being enabled including missing or open resistors, failure of another sub rail coming up etc I don’t know all the mechanisms tbh but there was a post here somewhere with the same missing rail and it was resolved so might be worth a search… though as I say, this would just be one of many reasons for the rail being missing :slight_smile:

when you say SOC where is that located because i remember u saying this in the thread early with a bad resistor it just i don’t where the soc is. another thread that i read was that it was the fuel gauge max 17050 when i tested mine all was ok. so am not sure where to go from here but speculation that the pmic is bad.

SoC is the main processor - the Tegra, largest IC on the board. Just to clarify, if 1V35 isn’t coming up as a result of not receiving an enable from the SoC it doesn’t automatically make it the SoC which is at fault, it could be for any number of reason including the ones I mentioned above.

It’s possible

How did you test it?

Unlikely if all other rails are being produced

How i tested was check the resistor near it. It supposely be 10 kohms which am getting and i tested the caps and also, there is a pad that goes to pin 1 which suppose to be (Ain) i tested resistance to ground and it was in the mega ohms. And plus its charging the battery. I even replaced it to see if there would be any difference which there was none. So i just put it back. And fyi i even change bq and m9 all voltages are ok and normal but again i know am repeating my self just no 1.35v to or from pmic.

While sometimes testing the surrounding components and skewed readings can shed light on whether the IC is faulty it’s not guaranteed and can still be faulty. Not saying that’s your issue but it’s worth bearing in mind :slight_smile:

Fuel guage being bad will typically only disallow high current charging (though not in all cases)… if your getting the typical 0.4/0.5A current draw then it could potentially still be at fault

As this is such a tricky symptom to diagnose (especially remotely) I suppose you could take a few hi-res pics front and back of the board, maybe I can spot something :man_shrugging: though no promises :slight_smile:

I can i will do it later since am not home i have a usb tester that shows me current draw. It would pull 5v @0.48amps and stay there the console will not start nor if i press the button. Btw this switch is the later model its HAD-CPU-01 motherboard. notice earlier switches will use the max77620A where as mine uses max77620H. Like the switch lite does.

I see, sounds like you have a Mariko revision. This fault is a lot more common on this rev for whatever reason as I expect the rail order has changed.

I guess there is no hope for me anymore cuz most videos and topics i search for its always different from mine.

Hi serverence,

As you wrote me one time, the Shorted cap on the Max ic is going directly to the SOC and the SOC is probably at fault, what your opinion on that?
The 0,48 amp draw is also a slight indication of that.

I Never fixed a console with this short, have you at any point, I really wonder?

Thank you

You won’t find videos on this subject because this is a real word repair that actualy requires brain power… something which most of the so called “pro” youtubers are lacking and can only deal with physical faults and dead shorts to ground.

Unfortunately this is a tricky one to help with remotely as it could be x20 different things… you could try measuring your primary rails (I won’t bog this thread down with this as I’ve covered more times than I can count :slight_smile: ) which would be a good first port of call :+1:

I may have said this based on other symptom variables, but on it’s own no it doesn’t automatically make it the SoC at fault

0.4A braindead could be one of a hundred things I’m afraid, I would say a good majority of the boards I work on have this symptom to the point where I don’t even bother checking it anymore as it doesn’t tell me anything :slight_smile:

What short?

small update. after 2 or 3 day i finally tackled the nintendo switch again so i decided to do some test around the max chip to refresh my memory of what i did and and resistance etc. so the 1.8v rail is still there 1.1v is there but i notice the 1.05v rail i would think is for the ram some how reduced to 0.867v and before i would get 1.05v and now the 1.35v rail is reading as a short to ground now???. i was so confuse checked it in ohms mode i get 0.05.6ohms and before it would get me 3.000 Mohms so i decided to remove the inductor and see where the shot is coming from. when i did that the short was gone… bottom pad would read at 3.000 M ohms and top pad would give me 4 to 5.000 M ohms and keeps climbing. i said ok let me just put the inductor back and test again when i did i let the board cool off and then test again nooooow am getting 556.000 K ohms it was so high and kept climbing i even reversed the probs to see if it would make a difference and it didn’t and after lets say 2 or 5 mins later the short did not returned but now it would get me 3 or 7 M am thinking it could or might as well be the max77620h at fault here. i notice that that chip is not easy to get like the max77620A am only getting it on aliexpress and that site is terrible for me. is there any better site i can order this?

OK GUYS i got an update since trying to get the max77620h was kinda hard to get i got 2 max77620A new. after installation am now getting all voltages 1.35v 1.029v 1.13v and 1.029 and 1.8v the switch is now trying to boot but i have a new issue is the switch was modded so now its stuck in rcm mode the pc will now detect it but in rcm mode. after a long research since i don’t know what rcm is. apparently it has Autorcm enable and i have to disable it in order for it to work but i need to get a memory card since i don’t have a spare laying around. i guess the max77620A can work on the mariko revision motherboards.

Switch lite and Switch V2 using optimized SOCs wich using less Power than the V1.

Maybe older MAX IC will cause some battery drain issues or something like this, but I would also assume that it will probably work relatively normal.

u maybe right am just trying to get it out of autorcm mode

Hi Calvin
where you find this boardview ? it possible to send a link to download it os cend me on i will be very thankful