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[SOLVED]820-3115 Green Light, No Boot

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iguystechshop

New member
I'm new here, and new to board repair. Spent 3 days with working with Jason last month to get started (which was awesome, by the way), upgraded all my equipment, and am now working on my first real MacBook board repair. I have a 820-3115 that's been liquid damaged. When I received it, it had no green light. PPVBAT_G3H was showing 0V. U7000 looked pretty bad so I lifted it, cleaned the contacts on the board and the IC, and resoldered. Now I have green light, but no fan. Started checking rails with PPBUS_G3H and found 0V.

Is replacing the SMC the next step? Or am I jumping to conclusions by going straight to the SMC?
 
bighead

bighead

New member
Why would you change SMC? Check short on PPBUS_G3H and replace that damn ISL from a donor board.
 
D

dukefawks

Administrator
Probably bad U7000 and sense resistor circuit/traces. Check resistance between pins 17/18 and 27/28. Also you do not reuse a garbage chip that costs $1.
 
I

iguystechshop

New member
dukefawks said:
Probably bad U7000 and sense resistor circuit/traces. Check resistance between pins 17/18 and 27/28. Also you do not reuse a garbage chip that costs $1.
Click to expand...

17/18 - about 16M, seems to vary slightly constantly
27/28 - 20.3

Still working on getting a good stock of donor boards and IC's. Found the thread that suggests where to find good donor boards and have ordered a bunch. Only donor board on hand had a U7000 that looked even shittier than the one on this board, so I decided to try to reuse it to see what happened. Since I got a green light afterward, I assumed (poorly) that I was getting somewhere with that reused chip. I certainly won't be reusing in the future once I have stuff in stock.
 
Gurmon

Gurmon

Member
Something not right on pins 17/18. This circuit should show around 2.7 - 3.0 ohms. Do R7051/R70512 look bad ? Anyhow change them as the reading are way off !
 
I

iguystechshop

New member
Gurmon said:
Something not right on pins 17/18. This circuit should show around 2.7 - 3.0 ohms. Do R7051/R70512 look bad ? Anyhow change them as the reading are way off !
Click to expand...

Yes, they do look bad. I meant to mention earlier that many of the caps and resistors surrounding U7000 look bad. I changed C7050, R7051, and R7052 and now pins 17/18 measure 3.2 ohms.


dukefawks said:
Corroded traces in the R7050/51/52 circuit is likely too.
Click to expand...

Traces seemed fine when I checked the other day, but I revisited that today and found something interesting. Pins 17/18 and 27/28 were shorting. I cleaned up the solder a bit and that fixed 17/18 but not 27/28. With 17/18 no longer shorted, I found that the trace from pin 18 to C7050 is bad, so I jumpered. Strangely enough, after jumpering, pins 17/18 are shorted again, even though solder work still looks good under the scope. Pins 27/28 look good under the scope too, but remain shorted. A check of all pins showed a short on 19/20 as well.

I'm inclined at this point to wait for the U7000 chips and/or the donor boards that I ordered before proceeding further. Seems like there's a good chance I'm just dealing with a shitty U7000, right?
 
D

dukefawks

Administrator
What do you call a short? 17/18 should be 3 Ohm and 27/28 about 20. 19/20 about 5 Ohm. Look at the diagram and understand why.
 
I

iguystechshop

New member
dukefawks said:
What do you call a short? 17/18 should be 3 Ohm and 27/28 about 20. 19/20 about 5 Ohm. Look at the diagram and understand why.
Click to expand...

Well, I meant that pins 17 and 18 have continuity to each other. Looking at the schematic and also referencing a good board, I now see that this is to be expected thanks to C7050, right? I was relying to heavily on the boardview, I guess.
 
I

iguystechshop

New member
dukefawks said:
Since when does a capacitor conduct DC? 17/18 are connected with each other through R7051+52+50.
Click to expand...

Right. Of course. Should have though that through more. Sorry for my ignorance...learning so much everyday.

So given that 17/18 is now showing an appropriate resistance and all the traces now check out ok, is my next step replacing U7000 with a known good IC?
 
I

iguystechshop

New member
dukefawks said:
Replace ISL
Click to expand...

Got it.

I have some on order from AliExpress, so it will be a little while until I get them. Do you know of any domestic sources for the part? I have been unable to find any so far. I would be willing to pay considerably more for the IC if someone sells it domestically just so I can continue with this repair.
 
I

iguystechshop

New member
I should have searched for the part number (ISL6259AHRTZ) because that led me to several options domestically, including buying them right from Louis. Which is what I'm going to do.
 
I

iguystechshop

New member
Replacing ISL with new chip and redoing jumper from for trace from pin 18 resulted in a booting board. Thanks for the help. Do I need to mark the title solved, or is that done by an admin? I don't see anywhere to edit the title of my thread...
 
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