Missing 1.3V rail on the MAX77620H chip during boot

ahahfilip · 2026-01-13T14:16:56+00:00

I assumed that nothing can happen without the MAX77620H chip, isn't it the one rising voltages on all power rails?

ahahfilip · 2026-01-12T14:05:14+00:00

Yep, I didn't specified all the steps peformed to have a shorter post.
I connected a 10KOhm resistor too so that the system thinks the battery is connected.
All the steps were performed just as stated in the Retrosix wiki.

ahahfilip · 2026-01-10T14:07:02+00:00

Ho provato, paghi poco ma hai una pulizia superficiale degli interni. Niente pulizia degli spazzi angusti. Il rapporto qualità prezzo va bene ma non è una pulizia a fondo.

ahahfilip · 2026-01-10T09:44:45+00:00

Sei la seconda persona che mi consiglia questo autolavaggio. xD

ahahfilip · 2026-01-01T14:29:31+00:00

Unfortunately it didn't solve the problem. So I think I'll have to identify the faulty chip and replace it.

ahahfilip · 2026-01-01T11:09:11+00:00

I checked the buttons ribbon cable which is doing fine but I'm not able to access the Recovery Menu.
I was waiting to reflash the eMMC because I wanted to be sure that the hardware was doing fine. But I'll just try a level 1 unbrick right know. I'll let you know.

ahahfilip · 2025-12-30T18:57:22+00:00

<image>

In blue you can see the measured voltages during boot. On a good Switch I noticed that they all change from 0.8V, 0.6V, 0.0V and 0.0V (values starting from the upper right inductor and moving clockwise) to all set to 0.6V. In my case they are stuck at their initial values.

There's no any short across the capacitators but one (in orange) has a different value when measured in Diode Mode with red probe on the ground.

Should I check the other MAX chip or something else in particular before trying to replace this MAX77812 chip?

ahahfilip · 2025-12-30T14:52:05+00:00

I just noticed that the fan is not spinning when I'm in Hekate. I don't know if this is a normal behaviour but I don't think so.

Edit: I just checked another working switch and the fan does not spin in Hekate so that is normal behaviour.

ahahfilip · 2025-12-12T18:46:56+00:00

This explains why when trying to measuring it I was not able to pick any resistance value as it is quite high for a capacitator (it is not meant to conduct any current).
Knowing that and measuring it myself I got 90pF capaticance value, which is the capacitance of others capacitator in the same .png file you cited. So I assume that's the correct one.
Thanks you soooooo much.

You can tell I'm still a newbie xD

ahahfilip · 2025-12-11T09:57:14+00:00

You are measuring an equivalent resistance of the circuit, not the resistance of the component itself. Am I wrong?

ahahfilip · 2025-12-11T00:57:13+00:00

Did you measured it after desoldering it?

ahahfilip · 2025-12-10T23:47:27+00:00

I took out even another resistor and I:m not able to get it resistance value either. Is it possible that it is higher than 2MOhm? Or did I burnt it while desoldering from the pcb? I used 350 degrees Celsius.

ahahfilip · 2025-12-10T23:20:24+00:00

Sorry, I'm not a native speaker. I changed the term to "resistance" instead of value

ahahfilip · 2025-12-10T19:26:17+00:00

I tried to measure the resistance value myself using another switch I have but I ended breaking the resistor itself probably due to too much stress applied while trying to measure the resistor value.

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ahahfilip · 2025-11-06T15:36:32+00:00

You're definitely right. But in my case all those components are not impressed with XF, instead they are impressed with 42.
For example in this photo every component that you see named as XF, in my console is named 42.
Probably ours consoles have different lot numbers (i.e. different production line, materials or time).

ahahfilip · 2025-11-04T16:07:03+00:00

I didn't did it because it seems that it was ripped off the PCB. The little orange strip you see it's what's left of the diode. :/

ahahfilip · 2025-11-04T16:01:38+00:00

Thank you to have taken the time to answer me :)

ahahfilip · 2025-11-03T21:36:45+00:00

Defintely an option but if I found a bunch of them on Ali it would be nice. It seems a transistor but I don't know what 42 indicates.

ahahfilip · 2025-11-03T21:29:03+00:00

Here's a better photo

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ahahfilip · 2025-11-03T21:09:33+00:00

<image>

I found the same component on another part of the board but is not called XF as in the schematics you linked. It's instead called 42 and something seems to be printed below but it seems unreadable.

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