Hardware Switch - hac21 , charge ok , no boot , no rcm detected , all V-rail good.

[ppzikos]

Hello , sorry i'm french I'm going to make simple sentences.

hello all

Switch : charge ok , no boot , black screen
without nand , no rcm detected ( plug with usb on laptop good work with other switch )

Switch hac-21
Charge ok , 0.4a / 5V
m92 pin 5-6 = 3.3V , vconn & cc1 ok at 1.5 v ...
Max77620 work, all of 4 power is good , 1.8 , 1v ,1.35v , 1.15v ( BQ &M92 good working)
SOC slow heat (normal)
diode test at 0.4v on usb data line , no short with other pin and all pin is good! usb very clean.
usb data line filter is good.
No short found on motherboard.

I'm not going to try to replace random components and I don't know where to look! and random search is bad (sometimes its working).
What does the soc need to pass in rcm?
we remove the nand, we plug the cable and it's good,
The soc needs its power ok, but does it need ram? does he check components before launching into rcm?
Maybe ram is wrong but i'have black screen not a blue screen..

i search ... have a good day

 

[thesjaakspoiler]

As far as I know, before booting into RCM, only the most essential things like memory and usb are initialized.
The NAND is not checked.
Note that Hekate and Atmosphere need files on the SD card to work.
LockPickRCM doesn't need anything for showing the first menu :
https://github.com/shchmue/Lockpick_RCM

A lot of things can be broken.
For getting into the RCM mode, your usb port, usb chip and the joycon connector needs to be good.
Can you see if the pins of the joycon connector are not bend or missing?
Another possibility would be that the chip that handles the usb data signals is broken.
Could also gently press down the Tegra while injecting the payload?
Some Switches have Tegra's with loose connections to the motherboard.
If you can't get into the RCM mode, the Switch just boots normally.
If the NAND is messed up then it will also just show a black screen (with the backlight on).

 

[ppzikos]

hi , thanks! , no backlight.

usb very good data line , checked under the soc !! i have re-ball this switch because I thought the mistake was his.
for force to rcm i know , > remove nand (no need jig).
there is no chip to ctrl data line of usb , it's usb > filter > SOC , sometime there is a IC for esd protect.
and i've 0.4v of each line in diode mode and +5 mega ohms of isolation.
the data line of d+/d- is very good. ,

the soc wont boot even in rcm but why ? charge is ok , bq & m92 is ok and max 77620 is ok too

either the ram is K.O, but I don't think , but i can test!
either the soc test a component that malfunctions. i know this.
or soc is dead , but i can test too if i reball soc on other good working motherboard!, i have a lot of motherboard for this!!

 

[Dark Ronin]

Have you tested capacitors around all soc's for conductivity? There may be a shorted ones.

 

[ppzikos]

thanks , re-test but no short found