820-00840 won't turn on

osmun38

New member
I'm having some slight issues. I'm very new to this but on most of the videos I've watched from Rossman he says to check the power rails within the schematics first but that is for older machines, and on this machine there is no "Always On" page with the power rails, so I have no idea where even to start.
 

osmun38

New member
This was the closest I could find to the power rails page
 

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osmun38

New member
just checked the first one on the board that I saw and it appears that C3121 is missing completely. No voltage on PPDCIN_G3H anywhere else on the board.
 

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osmun38

New member
Would I have to replace this with the exact same resistor from a donor board or what could I put there?
 

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2informaticos

Administrator
Staff member
"resistor"
???
In the pic appears a capacitor.
Which is also marked as "NO STUFF"; do NOT solder anything there!!!

Post resistance to ground on PPDCIN_G3H and check all input fuses.
 

JohnB8812

New member
Yes check resistance to ground on PPDCIN_G3H it should at least be 5 volts, but if it's zero, it could be shorted.
 

2informaticos

Administrator
Staff member
"C3121: 116 KOhms, 1.97V"
Use diode mode (red probe to ground) for such kind of test.
And don't test the same line in various points; is useless...

If 1.97V is a diode mode reading, don't post again the end "V"; just confuses us.
Red probe to ground should get reading lower than 1.000 in diode mode.

Do you get any voltage at F3000/10?
If not, check both fuses and resistance to ground on them.
 

osmun38

New member
Sorry about that, bear with me I'm learning very quickly all sorts of stuff I can't keep track of it all lol, but okay I'll check.
C3121: Diode - 568
F3000 and F3010: 4.97 V
 

2informaticos

Administrator
Staff member
So you get 0V at R7020?
Nor even pulsing there?
This points to a problem with USB-C controllers.
Post resistance to ground an all power rails of U3100/200.

"Any history liquid drop damage etc?"
???
 

osmun38

New member
R7020 PIN 1 and 2: 0V nor pulsing
u3200 chips:
PP1V1_UPC_XB_LDO_BMC = 133.8 KOHMS
PP1V8_UPC_XB_LDOD = 63 OHMS
PP3V3_UPC_XB_LDO = 9 OMHS
Yes it has been dropeed also an update its not reading any voltage for PPDCIN_G3H anymore
 

2informaticos

Administrator
Staff member
"PP3V3_UPC_XB_LDO = 9 OMHS"
Almost shorted; U3200 is the first suspect there.
But check C3208 first, just in case.
Pretty sure is not C/U2890 issue...

Post resistance to ground for PP3V3_UPC_XA_LDO too.
 

2informaticos

Administrator
Staff member
Post resistance between PP3V3_UPC_XA_LDO and PP3V3_UPC_XB_LDO (NOT to ground).
Seems that both U3100/200 are damaged...
 
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