head hurts....820-3209-a

[RESQ-MYTECH]

Now I know I am going to get ribbed... so here goes. I am trying to deduce this with through logic but not getting it right, i don't think.
Above board.... magsafe charger goes from green to orange... indicates PPBUS_G3H and PP3v42_G3H is present. Hopefully I have that right. Board is not powering on. PPBUS_G3H is showing 1.3v and PP3v42_G3H shows 3.402v. So, issue is more than likely PPBUS_G3H as I believe it should be 8.4v. Looking at the schematic, PPBUS_G3H comes out from F7040. Pins 1 and 2 show the voltage there as being 1.3v Taking steps back next point is L7030 which reads 1.299v on both pins 1 and 2 ( ignoring the minor difference in the voltage). Step back again to Q7030, pin 7 appears to be in Q7030 but pin 1 on L7030 looks like it is directly linked to pin 23 on U7000. Pin 19 VDD is reading 5.067v so i know that is getting power and pin 20 is get 5.064v, thus meaning R7001 is doing its job. back to q7030, pins 3/4/5 are GND. Pin 1 CHGR_UGATE is showing 1.299v. Pin 6 CHGR_LGATE is showing 0.0v. Pin 2 PPDCIN_G3H_CHGR is showing 14.8v, which is the same voltage at pins 2 & 4 on j6900. pin 3 reads 3.304v which if i am correct in thinking should be 5v??? Now here is the kicker.... when in diode mode, reading PPBUS_G3H at any of the points shown on the NET command on openboardview for a short to ground I am getting 0.0 ohms and a constant beep. Which again if i am right indicates a short. But nothing is getting hot.

Next logical step for me is to grab a bench PSU, of which i do not have at this time, inject say 3v into PPBUS_G3H say at pin 2 on F7040 and obviously blk to GND and see what gets hot then... correct?
Or is all that I have done above, over complicated things and it is either U7000 or Q7030 thats the issue?

Thanks for any input given...

 

[RESQ-MYTECH]

BTW, shou;d add, the board has been left in the MBA over night all connected and when i cam in this morning the LED was still orange and the battery had not charged... not sure if that is significant.

 

[2informaticos]

Do I need to repeat hundred time now?
Do NOT inject voltage before check all high-side MOSFETs from secondary supplies!!!

First, remove F7040 and see where the short remains.
You should get normal PPBUS_G3H at L7030 side if charger circuit is OK.
If short, or low value on system side, then check if any big coli has the same value to ground.
If yes, remove corresponding high-side MOSFET and test again.
As you get 1.2V on PPBUS_G3H, there is no pure short.
However, expecting very low value, use ohm mode (not diode) for readings.

 

[RESQ-MYTECH]

TBH, first time I have seen not to inject voltage.... so in my defence... thank you for the warning.
Right.... F7040 removed. Pin 2 still shows a short using diode mode. pins 1 and 2 on L7030 still show 1.3v. Pin 1 on D6905 shows short. pin2&3 do not show short. If I remove D6905 the short on pin 1 of D6905/ pin 1&2 of r6906 and pin 2 of F7040 show no short. With D6905 removed there is no short on any of the pins. Follow pin 3 from d6905 to pin 6 on U6990 shows no short. Replace D6905 and F7040, 14.52v shows at pin 6 & 8 on U6990. Pin 5 & 7 show no voltage ( pin 5 is GND). Pin 1 shows 1.29v, pin 2 shows 3.402v, pin 3 show 7.009v, pin 4 shows 3.402v

As for any big coil.... first set of figures is in diode mode and 2nd is in resistance mode.
L7030 both pins 0.0 ohms 0.0 ohms
L7630 both pins 12.9 ohms 13 ohms
L7550 both pins 3.6 ohms pin 1 3.6 ohms pin 2 3.5 ohms
L7510 both pins 5.9 ohms 5.9 ohms

I did readings in both just in case it might help.

At no point has PPBUS_G3H risen above 1.3v

 

[2informaticos]

You posted readings from some coils, bot not for pin 2/F7040, witj fuse removed of course.
STOP to measure both pins of a coil respect to ground; you cannot get different values!
Please confirm if you have short on both system side and L7030 with fuse removed.

 

[RESQ-MYTECH]

F7040, pin 2 shows. 0.0 ohms in diode mode and 0.0 ohms in resistance mode. this is with the fuse removed. when i remove D6905 the short on pin 1 disappears. pin 2 of f7040 is tracked to pin 1 of D6905 via a resistor R6906. There is no short to ground on pins 2 and 3 of D6905. I have replaced D6905 from a donor and the short returns. When measuring for a short on pins 1 and 2 of L7030 with the fuse removed I get O.L on the meter.

 

[2informaticos]

You cannot get 0 ohms on PPBUS_G3H because of D6905; R6906 has 4.7 ohms!!!
Do you still get 0 ohms on PPBUS_G3H (system side) when remove R6906?
Please provide accurate information.

 

[RESQ-MYTECH]

2informaticos i have drpped you a PM.