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820-00281 no 20V

G

grmacs

Member
Had bad USB chip. Now getting 5V at all 4 ports. No 20V

Power is reading 5V and around 300 mAmps.

Have enable on U6903 and 5V supply to it but only getting 3.1V out of it for PP3v3_G3H at pin 1 of L6900 and under 3V at pin 2 @ 2.8V.

Replace U6903? Voltage drop diode check of L6900 is .361V
 
G

grmacs

Member
Sorry about that. I changed the thread to 00281. I have 3 usb-C ports pulling 280 and occasionally and briefly 320mA. The fourth is pulling 80mA steady I believe the one that is corresponding to U3100. I changed U3200 as that port was not reporting any voltage/amps but now is at 5V.
 
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2informaticos

2informaticos

Administrator
Staff member
Compare diode mode readings on LDO rails of each CD3215 chip.
Do you get 1V1 LDO at the chip corresponding to the powred port?
 
G

grmacs

Member
Ok. Thanks for the direction. Not sure why it didnt check the diode readings on the caps of the ports that were working... Anyway, U3100 had a couple of LDO caps shorted to nearly 0V. I pulled them to check if it was the caps but it was U3100. Changed it and went well and shorts were gone but I was drawing 0 amps. I swapped the chip again... same thing? I'm not understanding what's happened. The chip swap went very smoothly. Chips I have already had balls so all i had to do was clean pads and flux and solder on. I've rechecked the area to see if anything moved or chips gone or anything (even though I have zero reason to think anything happened) and not seeing or understanding a reason why I'm not drawing anything. Checked fuses near the CD3215's and they're all good.
 
2informaticos

2informaticos

Administrator
Staff member
Do you get 5V at R7020?
Also "Do you get 1V1 LDO at the chip corresponding to the powred port?"???
Check all them.
 
2informaticos

2informaticos

Administrator
Staff member
Recheck U3100/200 area; you must get 1V1 LDO.
Maybe new chips are fake.
Compare diode mode readings in different points between left and right ports.
 
G

grmacs

Member
Diode mode readings seem to be consistent on both sides for all 4 chips. Nothing unusual that I'm seeing. I change both 3100/3200 again testing between and still getting nothing at all for 1v1 LDO on that side. Diode readings from pin 35 is .485V drop red probe to ground. Parts were new from Beetstech.
 
P

piernov

Moderator
Staff member
It's a regular 25-series SPI ROM so it can be flashed like any other. It can be swapped from same model donor board and same side.
It's been observed on a 820-00928 that the dumps were different between each side. I don't know if copying one side to the other would work as intended.
 
G

grmacs

Member
Ahhhh. I figured that was a stretch. I guess I need some donors unless there's someone that might sell the files.

Not finding any donor boards with sides or even just the sides... dah
 
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G

grmacs

Member
I have a working 2017 15" logic board with 4-USBC's. Any chance that USB firmware chip could be copied from same side of the board?
 
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