Hardware No power up on two mainboards

[Harpoon_GH]

Hello all.

First issue was switch was pulled off the dock by the headset cord. The USB-C port was damaged, pins were bent. I did continue to work out of dock until battery went low. Charger was plugged then a 'blue screen' appeared on screen according to an 8year old. It would not power up do anything. I got the USB port replaced by 3rd party. No dice. Battery seemsOK (2.5v per cell), no power on.

So i decided to buy a used MB from IFixIT. I installed that and same issue. No power on of any sort. No detection from computer USB. Besides getting a bad MB, what else can i check?

My original MB is early SN but not touched.

 

[Pintglass]

Hello all.

First issue was switch was pulled off the dock by the headset cord. The USB-C port was damaged, pins were bent. I did continue to work out of dock until battery went low. Charger was plugged then a 'blue screen' appeared on screen according to an 8year old. It would not power up do anything. I got the USB port replaced by 3rd party. No dice. Battery seemsOK (2.5v per cell), no power on.

So i decided to buy a used MB from IFixIT. I installed that and same issue. No power on of any sort. No detection from computer USB. Besides getting a bad MB, what else can i check?

My original MB is early SN but not touched.

What do you mean by 2.5v per cell, where has this figure come from

 

[Harpoon_GH]

Sorry, thought it was 2 cells. Then the battery is 2.5v. pretty sure i charged it yesterday so i am not sure why it is down to 2.5 if it is not on.

 

[Harpoon_GH]

MB#2 M9T236 Pin 5 = 3.2volts Pin 6 = 3.29v Battery is back up to 3.9 after sitting on the charger.

 

[Harpoon_GH]

MB #1 M9T236 Pin 6 Cap is shorted. I am guessing the PI3USB is bad because of plugging in charger with messed up USB pins.

 

[Harpoon_GH]

I don't understand MB #2. It is discharging the battery to 2.6 even though it is not on.

 

[Pintglass]

I don't understand MB #2. It is discharging the battery to 2.6 even though it is not on.

Test for a short to ground on pins 13 and 15 of BQ24193

 

[Harpoon_GH]

I do not believe those pins are shorted.

I am back to working on MB #1. I removed PI3USB but the short remained at M9T236 Pin 6 cap. Everything around the M9T236 is ok. Also the big Cap above PI3USB is shorted with or without the chip. I did replace the PI3USB chip.

 

[Harpoon_GH]

i have one choke circled in pic that is open. With the Nintendo charger in, I get 15 volts. I do not get any voltage on cap above PI3USB or M9T236 Pin 6, which i believe is the 3v3 rail? Could it be the open choke? can i bypass it?

 

[Pintglass]

i have one choke circled in pic that is open. With the Nintendo charger in, I get 15 volts. I do not get any voltage on cap above PI3USB or M9T236 Pin 6, which i believe is the 3v3 rail? Could it be the open choke? can i bypass it?

Test to see if the choke is shorted to ground if so remove it, and test to see if you're switch boots, at worst with the choke removed it won't give an image in docked mode.
If the choke isn't shorted and you've changed PI3USB and the short remains it could be one of the many cap's on the 3v3 rail, try removing the cap thats connected to pin 6 of the M92T36

 

[Harpoon_GH]

That choke is not shorted to ground. I am not finding shorts at the moment. I was not happy with the placement of the PI3 so moved it in place better. I put the MB back and I got the screen on! I have 3 volts on cap of pin 6 M92T after moving chip. It is just displaying low battery in corner. I think the battery is not charging or detected. I do have a new battery on order in case something is wrong with it. Might be amateur handy work replacing the chip also. At least it is turning on now.

 

[Harpoon_GH]

Just checked again, I was being impatient. The battery is charging and switch is working!

Thanks all!

 

[Harpoon_GH]

Unfortunately it is not outputting video from the dock. The dock turns green and charging but no video.

 

[Pintglass]

Unfortunately it is not outputting video from the dock. The dock turns green and charging but no video.

You won't get an image as one of the chokes under the PI3USB is open line, replace that.

 

[Harpoon_GH]

You won't get an image as one of the chokes under the PI3USB is open line, replace that.

Thanks. How bad is it to replace? It is pretty crowed in that area.