820-2262 - no power, no MagSafe light

mikiotty

New member
7.5Kohm 19/20 (seems a bit high...)
2.6Kohm 21/22

No short on Q7901/02.
D7903 diode mode:
- positive on pin 1, negative on pin 3: .595
- positive on pin 3, negative on pin 1: .793

Should I replace D7903 and the resistors on 19/20?
Sorry for all the questions, I'm quite new to this stuff!
 

2informaticos

Administrator
Staff member
Check R7904/5/6 and their traces.
As per schematic, calculate the resistance which you sould get between mentioned pins.
To be clear, measure between 19-20 and other measurment 21-22; didn't ask about measurements to ground.
 

mikiotty

New member
Yeah values are resistance between pins, not to ground.
Is R7906 supposed to be 2.2ohms or 2.2Kohms? Is it a typo in the schematic?

EDIT:
R7904 is about 7 ohm (should be 0)
R7905 is 5.7 Kohm (should be 18ohm)
R7906 is 2.6 Kohm (should be 2.2ohm)
Thats if I can read a resistance unit properly 😅
 
Last edited:

Vogelek23

Member
Is R7906 supposed to be 2.2ohms or 2.2Kohms? Is it a typo in the schematic?
No typo on the schematic - this is a filter resistor (along with C7902 it does reduce the switching noise) so it is of such low value.

R7904 is about 7 ohm (should be 0)
R7905 is 5.7 Kohm (should be 18ohm)
R7906 is 2.6 Kohm (should be 2.2ohm)
Of course all of these resistors must be replaced according to the schematic.
 
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