820-3536 PPBUS_S5_HS_COMPUTING is shorted

[sammobile]

Hi guys, I am not expert in Mac repair. Please help me find the solution.
Macbook came with some corrosion water. No power no fan green then orange cable when the charger is plugged.
PPBUS-S5-HS-COMPYTING is shorted ground. As I attached under q7630 there is a problem.
I took these components to see if I could find the shorted part.
c7622
c7624
r7202
r5400
q7430
q7630
q7310
c7619
l7630
But no lock still shorted. Except that area that I attached components seems fine without any issue or water damaging under the microscope.

 

[2informaticos]

First of all, welcome to the forum!

Post the exact ohm resistance of that short.
Compare with all big coils to ground.

 

[sammobile]

Thanks.
I didn't get, sorry. You mean I took off the components again from the board then measure the ohm.
Could you please explain more?

 

[2informaticos]

You've said to have short to ground.
0 ohm, 10 ohm, how much???
Compare that value with resistance to ground on all big coils.
No need to remove anything (yet).

 

[sammobile]

It shows 0.03 ohm compare to other big coils It is same amount.0.02 or 0.03

 

[sammobile]

Bad news. I found ppbus-g3h and ppvbat g3h chgr reg is also shorted.

 

[2informaticos]

I hope you've disconnected power from the board, before measuring in diode mode.
In fact allow 10-15s, to discharge any remanent voltage.

I was talking to compare with ohm resistance to ground on big coils.
You cannot get 0 ohm on all of them...

I specified OHM value, not diode mode.
I doubt you can get 0.03 ohm, nor even in ohm scale; multimeter probes give aprox 0.3 ohm already.

 

[sammobile]

No, the power was disconnected. I was just testing board without connecting to power.
I know I look stupid and very amateur but really want to solve it. Yes I tested on diode mode yesterday.
Could you please tell me in which range ohm of multimeters should I test?
Also, I found out PPBUS-GH3 and PPVBAT-GH3-CHRG-REG were shorted as well. After I took F7140 off of board, the other way which is PPVBAT-GH3-CHRG-REG returned to normal and not shorted. So still PPBUS-GH3 and ppbus_s5_HS_COMPUTING are shorted to ground.

 

[2informaticos]

Actual multimeters are all auto-range.
If not, choose 200 ohm scale.

 

[sammobile]

Most of the big coils are shorted for example:
c7543
c7540
c7542
c7580
c7314
c7313
c7324
I can not compare because all are shorted. I get 1.8 ohm on all of them. Only one c1031 I get 63.1 ohm
I confused.

 

[sammobile]

Update
I took off these components to check the board. L7130 I have shorted ground on pin2 of l7130. Also, r7150 only pin2 is shorted. F7700 PIN1 is shorted , pin2 is normal.
Am I wasting time with this way of testing?

 

[2informaticos]

You waste time if you do not want to post short values, as already asked.
If you only mention several components connected to the same rail, what you see intersting?

You can consider short some low values, as 5-20 ohms, which can be good values, depending where you measured.
Is IMPOSSIBLE to get short on all big coils to ground!!!

Can you post again accurate ohm value to ground measured at PPBUS_G3H?
R5400 is an easy to access test point.

Then post EXACT resistance to ground at L7310/20, L7430, etc .

 

[sammobile]

R5400 all pins shows 1.9-2.1 ohm.
L7310: 59.5 OHM
L7320: 59.5 OHM
R5510: 270 OHM
R7310/R7320: 65 OHM
C7440/1/2 L7430 : 270 OHM
L7520 :1270 OHM
L7560: 7.76k on 20K OHM
C4696/C3387/C3287 7.7 K OHM not fixed range.

and ground pin on others like c7740/1/2 is 0.08 ohm
Thanks for following

 

[2informaticos]

"and ground pin on others"
Do you mean that you'ne measured ground to ground???
Be serious man.
Do not post more than we need here...

If no big coil has the same resistance to ground like PPBUS_G3H, then you are safe to inject voltage.
Start injecting with 1V and slowly go uo, if needed (at R5400, for example).
Set first amp limit to max on your lab PSU.
Then check with your fingers where the board heats.
Should be some cpacitor shorted, on PPBUS_G3H power rail.

 

[sammobile]

I connected the power as you told me to the battery connector also r5400 from 1v to 2.5v. The only part got heat q7630 under the IC a layer of the board was pilled off I took it with cutter. See the picture. Also, c7619 I took it off. But the place under Q7630 when I connect to power is burning smoking. Nothing gets hot on PPBUS_G3H power rail.

 

[2informaticos]

You've probably fried the board now.

I don't really understand what you did.
I said to conect lab PSU to R5400; starting with 1V.
Who said something about battery connector???

Don't tell me thay you powered up the board with battery (or charger) and also inject voltage with lab PSU to R5400.

You didn't report any short to ground at L7630 before.
Probably killed the CPU now...

 

[sammobile]

I understand. Check my first post I reported PPBUS_s5_hs_computing rail is shorted. Also I reported L7630 is shorted.
At the first view when I saw the motherboard found out the Q7630 was defective. I posted the picture first post. Under the IC a top layer was ripped and was peeled off half.
I connected positive hub of power supply to r5400 and negative hub to ground started 1v then went to 2v same area started smoking.

 

[2informaticos]

I asked you several times to post exact ohm value of that short.
In the first post you mentioned lot of components, but didn't post exact values.

I asked lot of rimes to compare short value on PPBUS_G3H with ALL big coils; never got an exact reply.
If Q7630 was the reason for shorting PPBUS_G3H to L7630, then I didn't expect to still have short on PPBUS_G3H, once Q7630 was removed.
Unless you have a short between copper layers, under Q7630.
And that is a big problem; not sure if you can properly clean that area and resolder the MOSFET correctly.

However, if you lift L7630 and get short to ground on its pad 2 (R7640), then CPU is dead; do not waste more time on this board.

 

[sammobile]

Sorry for delay here was holiday.
Yes you are right. I had a shorted ground under Q7630. I shaved the surface then short gone. So I don't have shorted on PPBUS-G3H and PPBUS-S5-HS-COMPUTING anymore but yes I have short under l7630 pin2 and r7640 pin1.
I am a cellphone technician recently I am trying to learn and fix computers as well, so I am an amateur. Thanks for helping me.