A2159 820-01598 Stuck on 5V looping on both ports, with pulsing heat on U3200

it-solve

Member
I got this A2159 820-01598, which have looping 5V 0.3A on the charger.
U3200 shows a pulsing heat signature on both charging ports. While PP3V3_UPC_XB_LDO is shorting. PP3V3_UPC_XA_LDO shows 0.5Vdc.

I don't see any liquid damage on the board itself, only the bottom of the battery sensors flipped red.
I just got the chips today. Shall I replace U3200 first? If there is something else, I should check first to prevent shorting the replaced chip. Avoiding wasting chips, ubelievable how expensive these chips are for new macs?

I can't detect any shorts on the major coils, CDxxx fuses, or bigger filtering caps.

Thanks
 

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it-solve

Member
No short on chip removal replaced it and also no short. Seems like U3200 was shorting internally.
Also, no more heat signatures on it, but still loops at 5V.

The only heat signature I detect is u2890/bios?, pulsing to +/- 10*C

Also noticed that PP3V3_G3H_RTC leg of C3100 is dissolved. Removed the C3100 while testing, its filtering cap should not affect it right?

Where to next?
 

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2informaticos

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Both USB ports have the same behaviour?

If all AWAKE and SLPS2R voltages are present, machine should enter DFU.
 

it-solve

Member
Yes both USB-c loops, although the one closer to the screen (top one) loops every 15 sec, compared to the bottom one every 5 sec. Not sure which one is U3200. Suspecting the bottom one is U3200 USB-C port

PP1V8_AWAKE - Loops 1.85V
PPVDDCPU_AWAKE - Loops 0.75V
PPVDDCPUSRAM_AWAKE - Loops 0.80V
PP1V8_AWAKE_SOC_TSADC_RC - Loops 1.80V
PP1V8_AWAKE_SOC_FMON_RC - Loops 1.80V
PP1V2_AWAKE - Loops 1.21V
PP1V2_AWAKE_SOC_PLLSOC_F - Loops 1.20V
PP1V2_AWAKE_SOC_PLLCPU_F - Loops 1.20V
PP1V2_AWAKE_SOC_PCIEREFBUF_F - Loops 1.20V
PP1V2_AWAKE_SOC_PCIEPLL_F - Loops 1.20V
PP3V3_AWAKE - Loops 3.24V

SOC_BLUE_AWAKE - 0.01V - Expected?

SLP2SR I don't have those lines, Do you mean PM_SLP_Sxx lines? PM_SLP_S0/S3 lines does not have any voltage on them
 

2informaticos

Administrator
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Use boardview to identify each USB port and CD3217 pair.
Compare diode mode to ground on LDO rails of both chips.
Check for short on all big coils (secondary power supplies).
 

it-solve

Member
Top USB-C - U3100 - XA - Loops every 15 sec
Bottom USB-C - U3200 - XB- Loops every 5 sec - the one which got replaced

U3200
PP3V3_UPC_XB_LDO - 0.49Vdc
PP1V5_UPC_XB_LDO_CORE - 0.52Vdc
PP3V3_G3H_RTC - 0.32Vdc

U3100
PP3V3_UPC_XA_LDO - 0.51Vdc
PP1V5_UPC_XA_LDO_CORE - 0.51Vdc
PP3V3_G3H_RTC - 0.32Vdc

Let me know if I missed CD3217 LDO line, these seems to be the ones around them.

Went through all bigger filtering caps, coils as well as fuses. No short to be seen. Only close proximity to the CPU coils and caps shows a low resistance.

Found PP1V8 SLP2SR line, which seems ok at 1.8V

Also noticed UPC_XA(B)_FAULT_L to jump 0V->0.15V when it loops 5v->0V
 
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it-solve

Member
Went inch by inch under a microscope, the only liquid sign is around the bottom of the battery where the trackpad is. No other liquid signs. Apparently water bottle leaked in a backpack.
I'm testing on a bench with a USB-C port attached only

Also noticed that PP3V3_G3H_RTC leg of C3100 is dissolved. Removed the C3100 while testing, its filtering cap should not affect it right?
 

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it-solve

Member
PP3V3_G3H_RTC - 3.30V / 0.42Vdc on all three pads with removed U3100. looks normal right? Shall I resolder new CD3217. This is the last one I have.

How do you reball CD3217, Is it worth it? I have seen some stencils available.
 

it-solve

Member
Thanks for the tip. So clean with fresh solder and wick, apply solder paste on stencil and hot air until it creates balls? Do you have a video you came across to see?

How is PP3V3_G3H_RTC voltage/resistance sounds like? Shall I solder a new chip and try?
 

2informaticos

Administrator
Staff member
3V3_G3H readings look good.

Use minimum air flow, when create the balls.
I recommend you to remove the nozzle from hot-air station also.
 

2informaticos

Administrator
Staff member
Of course.
I don't know if you can find and use an universal model.
Like the ones for mobile phones repair, with several layouts in the same sheet.
 

it-solve

Member
Replaced U3100, still stuck on 5V 0.25A. With a difference that both USB ports loop every 15 sec.

I am out of ideas. Any suggestions?
 
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it-solve

Member
A strange thing happened, I have soldered U3200 with the one which was there previously and now 5V 0.2A stays stable with no looping on both ports. Does that mean anything? Is it worth fighting with this case?
 
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