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A2337 - 820-02016-A - short on PP0V9_ATCRTMR1_VCCA

S

samstown

Member
Hi,

Macbook get 5V and stay at 0.16 - 0.40 amp. I found a short on CF131 PIN1 near UF500. It's PP0V9_ATCRTMR1_VCCA. It's connected to CF143, CF130 and RF101 and RF100.

I want to make sure my diag is correct. I have .019 on diode mode, so it really looks like a short. Compare to simialr cap CF031 show .458 near UF400.

So I have three potential cap that could be sorted. I should inject 1V 2amp to find the right one ?

Thanks
Sam
 

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2informaticos

2informaticos

Administrator
Staff member
You can claim for Nobel prize if you inject 2A with 1V into 0.019 (diode mode).

You can inject until 1.2V there, but the current will be very low; depending on the ohm resistance to ground.
No way to get anything hot.
A performant IR camera may detect some small temperature difference.

I always said: SET AMP LIMIT TO MAX ON PSU FIRST.
 
S

samstown

Member
RF101/2 is ok now. RF101/2 still shorted, that's PP3V3_S2SW_USBC1 and it's connected to a lot of capacitor and UF750 and UF115, UF740...
 
2informaticos

2informaticos

Administrator
Staff member
So the short is not on PP0V9_ATCRTMR1_VCCA; as expected.

Many components connected to PP3V3_S2SW_USBC1; including UF100.
You should test UF115 and UF740/50 first.
 
S

samstown

Member
nothing visible on UF115 and UF740 or UF750 or around. I measure the short on each chip. So in this case what's the plan, remove one by one to check ?
 

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S

samstown

Member
short is gone, I removed UF115, UF740 and finally UF750 (that was the culprit). I have 5 V, 04 Amp on both USB-C port, I see U0500 getting a little bit warm with thermal camera then getting cold again.

Macbook can boot without UF115, UF40 and UF750 ?

I see UF015 getting warm for a while then cold again. Same for UF500. UF400 stay warm, no pulse.

L5800 also get warm but stable.
 
S

samstown

Member
replaced UF000, UF100, UF400, UF500, UF115, UF40 and UF750 and all caps and resistor.
When plug USC-C power supply, I get 5V 0,2 amp for 5 seconds then it drop to 0,06 for 2 seconds amp then it stop and restart and does that over and over.
 
S

samstown

Member
PPBUS_AON diode mode on F5200/2 = .515 and 12V and drop to 0 when restart
PP3V8_AON_VDD_MAIN diode mode on CW10E = .191 and 3.8V stable
 
2informaticos

2informaticos

Administrator
Staff member
Compare diode mode readings on various points around UF000/100.

Do you get correct LDOs on U8100 and U7700?
 
S

samstown

Member
I've compare various points (15) around UF000/100, they have similar value.
I am not sure about LDOs, I see PP1V4_LDO_PREREG at 1.39 V on L84E0/2
I see several connection for PP1V5_VLDOINT_MPMU under U8100 but i don't have a test point to measure. I've search around U8100 but i can't see other LDO signal
 
2informaticos

2informaticos

Administrator
Staff member
Mentioned LDOs appear on pages 34 & 29; don't bother with the ones marked "NC".
You should find capacitors on the opposite side, as test points.
 
S

samstown

Member
DFU not possible. Actually, I have a short on CAP_PPSPMU_VLDO9, Diode mode = 0.001. As far as I see, there's only two capacitor connetec to this line. Should I try to remove both ?
 
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