Re: To all the MacBook BGA Reball repair doctors... expert question
[ATTACH]252081[/ATTACH]Hi Spider, here are the files. The trace seems intact (assuming it's the angled trace to the bottom left of the pad. Given it's a .3ohms short on the pad I think the short is there, not sure. Could always reinstall the pmic and inject voltage...Re: To all the MacBook BGA Reball repair doctors... expert question
[ATTACH]252081[/ATTACH]Hi Spider, here are the files. The trace seems intact (assuming it's the angled trace to the bottom left of the pad. Given it's a .3ohms short...
JM1010
Member
Last Activity: 03-12-2022, 08:51 PM
Joined: 09-26-2021
Location: Ottawa Ontario
-
To all the MacBook BGA Reball repair doctors... expert question
My Macbook 1707 PMIC got hot. Removed the chip and the fifth pad from the bottom left (PP5V_S4) was burned. After carefully scraping the pad to expose some copper it shows a 0.3 ohm short. I know this is a complex issue but what is the best way to deal with this? Where is the trace to this pad is also not clear. Is it fair to assume we need to scrape away the ground plane around this pad? If so, which layer is ground: is it top or second layer?. If it's not the best way to deal with this, what do you recommend ?
Thanks for your guidance.... -
Re: Macbook A1707 short on PPBUS - nothing gets hot
Hi Mon, as stated previously it's on pin 1 of L7600. Also I need to sort out the situation with pad 5 of the pmic. Do you have any advice? thanks again.Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Regarding PP3V3_G3H, can't check right now as waiting for new PMIC but I recall it was fine as the CD3215s were able to negotiate 20V at the charger.Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Hi Mon, it is pin 1. Actually I was confused about the creation of that rail between U7650 and the U7800 PMIC. The PP5VS4 pad on the PMIC bottom row fifth from left side was corroded. I started scraping the corrosion and may have hit some ground. That's quite technical but do you think ground is the 1st layer and I can scape some more to create space around the via? PP5VS4 seems to be going everywhere from that pad so I can't just run a wire, need to figure out how to repair and connect to the pad.. I think if I can get through...Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Hi Mon, are you suggesting an ESR is needed to move ahead with identifying the shorts on my rails eg PP5VS4? I still wonder what these rails have in common as all the problems happened at the same time.Last edited by JM1010; 12-21-2021, 09:35 PM.Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Funny coincidence Spider, Rene from Macbook Repair Ottawa tried to fix my board and removed one of these caps. Caps were fine, shorts are still there. Board is back with me to fix. Cheers.Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Thanks Mon, just momentarily pulled it out to take a reading. Unfortunately this short is on the PP5_S4 side (3.4 ohm)Sorry I forgot to record the other side but it did not beep.
So that leaves me with a problem on PPBUS, PP5V_S0, PP5S4 but not S5, PP3V3_TBT, PP3V_S0_left but not PP3VS0. Oh My.... for a no liquid laptop it's quite an handful
. Any chance they have one or two things in common? Trying to solve this puzzle logically
Last edited by JM1010; 12-21-2021, 06:14 PM.Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
U8209 Pin 1 is pp5v_s4 @ 4 ohms. Other 5V: pp5V_S0 @ 3 ohms, PP5vs5 is good
Correction PP3 rails
PP3V3, pp3v3s5, PP3_S0 are fine PP3_S0_LEFT is 4 ohms and PP3V3_TBT 1 ohm. Maybe something funny going on with U8295.
The board is out of the case. I'll check the connectors nevertheless.Last edited by JM1010; 12-21-2021, 05:01 PM.Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Reformat, was tired hope it's a typo. Was careful to keep voltage below 2V and current below 3 amp.
Mon regarding the PPBUS short, I didn't have to pull out the fuse(s) as I think I have my answer and I'm pretty sure the short is on the load side (unfortunately).
Both the ISL coil L7030 and the Q7030/40 mosfet gates are not shorted. Only the Q7040 output is shorted. (PPBUS).
I've poked around and this is what I have thus far. Some of these rails have pretty low resistance to ground. Unsure which...Last edited by JM1010; 12-21-2021, 03:25 PM.Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Thanks a million Mon. I owe you one. Maybe a beer in Windsor some day
Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Exactly what I had in mind Mon. Really hope it's on the source side.... Irrespective of which side it is, what would be the next step? On the list for tomorrow.
As a side note I also have some PP5 and PP4 rails shorted. Could (should) be related to same problem. Again this is not a water damage board. All happened at once. Weird.
I'll buy some freeze spray, should help till I can put my hand on a thermal cam such as the seek pro.Last edited by JM1010; 12-20-2021, 08:44 PM.Leave a comment:
-
Re: Macbook A1707 short on PPBUS - nothing gets hot
Thanks Mon and Reformatt for chipping in. I'm dealing with a PARTIAL short @ 50 ohms and this makes it difficult to find anything warm. I wish I had a thermal cam but i don't. I carefully inspected the whole board, applied IPA etc, nothing really gets hot.
As it currently stands PPBUS is partially shorted ( priority) as well as PP5_S5 and PP4V.
The PCH is quite warm but I think it may be normal or due to one of the shorted rails.
I wonder if there are other ways to identify the source of...Leave a comment:
-
MACBOOK: Basic safety question before injecting voltage
A1707 PPBUS has a partial short to ground @ 50 ohms.
VCORE to ground is 4 ohms.
Between PPBUS and VCORE I get 50 ohms as well.
Is it safe to inject 1-2 volt into PPBUS?
I remember piernov on Logiwiki stating that if PPBUS ohms to ground is LOWER than VCORE ohms to ground it is probably safe to inject small voltage into PPBUS. If it's the same resistance to ground it is not. But what about when PPBUS resistance to ground equals resistance between PPBUS and VCORE eg 50 ohms AND VCORE resistance to ground is lower eg 4 ohms? Is it safe to inject voltage into P...Last edited by JM1010; 12-20-2021, 12:22 PM. -
Macbook A1707 short on PPBUS - nothing gets hot
After using a bad charger (cord chewed by dog...) Macbook died.
Getting 20V and oscillating 0 and .2amp on amp meter
PPBUS is shorted (.8V)
After checking resistance with Vcore (ok), injected 1 amp, then 2 finally 3 amp on PPBUS and nothing seems to get hot except the PCH (barely tolerable to the touch at 3amp.)
If I can't detect anything getting hot @ 3 amp, what else can I do??
Thanks in advance. -
Re: New Members - please post your introductions here
Hi everyone. New here. I'm a hobbyist trying to fix his iphone 8. Thanks whomever posted the schematics for this phone. Unfortunately it's a bvre file. It's not worth paying $170 for one phone. anyone knows of a FREE BVRE viewer or brd converted? Thanks in advanceLeave a comment:
No activity results to display
Leave a comment: