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A1932 820-01521-A

H

hgoncalves

Active member
Hi,

I have an A1932 820-01521-A that puls 20V from ampmeter, but only consumes 0.20A from bench PSU.

I already tried the revive and restore without sucess. Can it be T2 related problem?

Can you help?
 
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H

hgoncalves

Active member
Hi,

No history. Client says that It stoped sudently.

The DFU fails with error (I'm doing the DFU with a M1 Pro. Not sure if incompatible):

"The System cannot be restored on this device.
Gave up waiting for device to transition from DFU state to DFU state.
[com.apple.MobileDevice.MobileRestore -OXFCA (4042)]"

PP5V_G3S = 5.122V
PP3V3_G3S = 3.294V
PP1V8_G3S = 2.936V (not sure if the value is normal, but recheked on several places with same value)

PP0V9_SSD = 0.9V
PP1V8_SSD = 1.8V

It seams that it is rebooting. It goes from 0.03A to 0.20A, and reboots.
 
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2informaticos

2informaticos

Administrator
Staff member
Did you test the board alone on the desk?
CPU core tries to appear?

Check for short and voltage pulse on all big coils.
Inspect audio board/flex for liquid signs.
 
H

hgoncalves

Active member
I did tested it on the desk alone, without anything else connected, and it has the same behavior.

CPU core is always stable at 0V.

All big coils seams to be ok, except L7210, L7430 and L7410 that only have 8 ohm to ground and 0.012 on diode reading (again, not sure if normal value) and no pulse.

L7030, L7690 and L7670 have voltages that oscilates whille rebooting

Don't know if it relavant, but the only thing that gets hot is the T2chip, but with only around 33º C, and U3200 with around 30ºC

Audio board seams ok.
 
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2informaticos

2informaticos

Administrator
Staff member
8 ohm may be good value on CPU coils; better to compare with good board.
Pulsing voltage on mentioned coils means the board tries to start, but some sensor is triggered (overcurrent probably) and power cycles.
Apart of big coils, do same tests at page 67 outputs.
 
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hgoncalves

Active member
I don't have other board of those to test it. Do you happen to have these reference values from another diagnosis that you have already made?

I'm not sure if is these that you asked, but my page 67 is about the KB/TP.

L6700 = 3.4M ohm and oscilates bettwen 12.29V to 12.60V
L6701 = 2.2M ohm and steady 3.307V
L6702 = 45K ohm and oscilates bettwen 0V to 3.295V
L6703 = 1.8M ohm and oscilates bettwen 0V to 5.123V
 
H

hgoncalves

Active member
Sorry. I haven´t undestood it.

U8240 - PP1V2_S0SW = 2.6K ohm and steady 0V

U8210 - PP3V3_G3S = 7.28M ohm and Oscilates from 0V to 3.298V

U8220 - PP1V8_G3S = 450K ohm and Oscilates from 0V to 1.803V

U8225 - PP3V3_G3SSW_SNS 0 = 5.2M ohm and 0V

U8200 - PP3V3_TBT_X_S0 = 60K ohm and 0V
 
2informaticos

2informaticos

Administrator
Staff member
Why do you still continue to check in ohm scale for high resistance to ground?
How many times need to repeat about diode mode?
Switch to ohm scale ONLY for very low readings; usually under 0.010...

I don't actually have any 01521 for comparison, sorry.

"PP1V8_G3S = 2.936V"
If true, check PP1V8_SLPS2R too.
 
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