820-00165 pp3v3_s5

[shanenin]

I have a board I was working on and noticed what seems to be the first issue. I have no voltages on pp3v3_s5. My strategy was to look in the schematics and search for a chip it was the output on. I have gone through the schematics many times and must be missing it. The closest chip I found was u7501 on page 54 of the schematic, but that does not seem to clearly indicate that is the source. I see lots lines with pp3v2_s5 as the prefix. But none with just pp3v3_s5 by its self. Could you help me understand what all of the other versions of pp3v3_s5_**** mean? I am just looking for a basic understanding in general. Also, where exactly is pp3v3_s5 come from?

 

[2informaticos]

PP3V3_S5 comes out from L7220 and is controlled by U7200.
First of all check resistance to ground on that coil; dioe mode, red probe to ground.
Post voltage for U7200, pins 3, 6, 8, 13, 16, 17.

Do you get Magsafe light?
Post exact voltage for PPBUS_G3H and 3V42.

 

[shanenin]

How come when I do a search for L7220 in the schematic or brd I am not getting any results? My PPBUS is 8.6v and, I am getting 3.42v on pp3v42. I do get magsafe light

I will check those other ones when I get to the shop.

 

[2informaticos]

Ooops, this is 00165 board...
So read U7501 instead of U7200.
Obviously the coil is L7520.
And the pins of interest (U7501) are 12, 13, 22, 23, 29.

Sorry, I was looking wrong schematic, as I have more than 10 opened in Adobe reader...

 

[shanenin]

thanks for helping me work through this. I am not sure why, but I am now getting pp3v3_s5