820-3437 No green light

[Japtastic]

Some progress...

Q3080 led me to the right direction.

PP15V_TBT was shorted to ground. I have now removed a number of caps on that line and the short is now gone from PP15V_TBT.

I put back on F7140 and Q7130 and retested. No more dancing 14.4v at DC IN But still no green light. Will test the basics again now.

Sorry, shorted D-S? What does it mean?

 

[2informaticos]

Drain to Source?

 

[Japtastic]

Measurments are now:

PPBUS_G3H = 14.4v
PP3V42_G3H = 3.42v

U7100:
Resistance between pins 17+18 is now 80 ohm...
Resistance between pins 27+28 is still 20 ohm.

 

[jason_microsoldering]

Replace Q7130 as well as U7100 simultaneously, then check ppbus g3h again. Battery side current sensing probably is also causing no green light.

 

[Japtastic]

Thanks, will do.

I just changed R7151 and this got me back to 3.6ohm between 17+18 on U7100.

 

[Japtastic]

Changed both at the same time.

U7100 was new. Q7130 from a donor.

Same situation though, nothing better or worse.

Q7130:

Pin1 = 4.57v
Pin2 = 4.57v
Pin3,4,5 GND
Pin 6 = 0v
Pin7 = 4.57v

Let me know if you need pin voltages from U7100 or anything else.

Cheers

 

[2informaticos]

High-side Q7130 seems to be shorted...
Check if beeps D-S?
When change U7100, check if pins 21/24 are properly soldered; if not, Q7130 gets burnt.
Also, don't forget about Q3080...

 

[Japtastic]

Yes you were right, Q7130 D-S was shorted. Swapped for another one and short has gone.
U7100 21/24 are good and have continuity to Pins 1/6 on Q7130
Q3080 D-S was shorted so removed for now.


PPBUS_G3H = 4.57v

Sorry this is taking so long.... The learning curve is steep but I'm taking it all in!

 

[jason_microsoldering]

Q7130 killed U7100 now... And probably killed Q7130 too.

 

[Japtastic]

While I was trying to figure out what was going on, I looked for more shorts and found that U3090 had shorts to ground on TBTBST_SNS1 and TBTBST_SNS so I have removed that chip just in case. The shorts to ground on those lines are now gone. No change in PPBUS_G3H...

U3090 is just thunderbolt isn't it? After removing this chip, I tested ground and there is no continuity to ground on pin/pad 37. There is on my donor boards. I'm not sure what this means in regards to troubleshooting. I will continue to look for more shorts. Is this what you call a rabbit hole?

So do you think the right plan of action is look for more shorts and then replace U7100 and Q7130 again?

 

[jason_microsoldering]

U7100 still dead, remove and compare diode mode measurements on ppbus g3h to known good.

 

[Japtastic]

Thanks for the reply. I don't have a known good board Donor with U7100 on the board, PPBUS_G3H = 410 Donor with U7100 off the board, PPBUS_G3H = 120

These are my PPBUS_G3H measurements with U7100 on the board I'm trying to repair.

R7006 Pin1 = 117
R5501 Pin1 = 118
Q5500 Pin4 = 119
R5450 Pin 2 = 120
R5430 Pin 2 = 120
F7140 Pin 2 = 120
R3080 Pin 1 = 120
C3080 Pin 1 = 120
Q3080 Pin 4 = 120

These are my PPBUS_G3H measurements with U7100 removed from the board I'm trying to repair.

R7006 Pin1 = 109
R5501 Pin1 = 109
Q5500 Pin4 = 109
R5450 Pin 2 = 109
R5430 Pin 2 = 110
F7140 Pin 2 = 110
R3080 Pin 1 = 111
C3080 Pin 1 = 112
Q3080 Pin 4 = 113

So anything wrong here apart from U7100? Shall I take the U7100 from the donor? This will be the third one.

 

[Japtastic]

Progress again!

So I took that U7100 from the donor board and now I have PPBUS_G3H and PP3V42_G3H

So it seems that the problem was that the short I found on the PP15V_TBT circuit was taking out U7100...?

Still no green light so on to more troubleshooting.

 

[Japtastic]

No Title

PPBUS_G3H = 8.54v
PP3V42_G3H = 3.34v

But....

This explains the burning smell from when I injected 3.4v originally. I thought it was from that area but couldn't be sure. Also explains no green light. New DC IN Board and Flex cable ordered. Can't find J9500 on ebay so will have to swap from a donor. Thanks for all your help so far. I'm hoping that replacing these parts will resolve everything.

 

[Japtastic]

That connector was a pain but all sorted. I have the new DC in board and flex cable connected. I have green/orange light

It still will not turn on though.

PPBUS_G3H = 8.5v
PPBUS_S5_HS_COMPUTING_ISNS = 8.5v
PPBUS_S5_HS_OTHER_ISNS = 8.5v
PPDCIN_G3H_ISOL = 14.9v
PPDCIN_G3H = 14.9v

PP3V42_G3H = 3.42v
PPVRTC_G3H = 3.32v

PP5V_S5 = 5v
PP3V3_S5 = 3.32v
PP3V3_S4 = 3.32v
PP5V_S4RS3 = Dead / Pulsing
PP5V_S4RS3_EN = Dead / Pulsing
PP5V_S0 = Dead / Pulsing
PPVCC_S0_CPU = Dead / Pulsing

The pulsing is so quick that the multi meter has trouble recording the values.

Nothing looks corroded here but I have checked all resistors, traces and continuity around Y1905, U6100 and U1900 and everything checks out. I haven't changed any caps yet.

 

[Japtastic]

Any ideas chaps?