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820-3476-a Power no display

Anterweb

Anterweb

Member
Signs of liquid damage but doesn't look that bad, Get green then orange light on charger fan spins no display on internal or external.

Board only on desk took these

ppbus_g3h - 12.53V
PP3V42_G3H - 3.41V
PPVRTC_G3H - 3.33V
PP5V_S5 - 5V
SMC_LID - 3.41V
PP3V3_S5 - 3.31V

Just waiting for the Ultrasonic to warm up and will run it through so if it makes any difference, probably not , What to try next?

Thanks in advance.
 
Last edited:
Anterweb

Anterweb

Member
Coils as follows
L7130 - 12.52v
L7520 - 0v
L7430 - 0v
L3095 - 0.01v
L7560 - 3.33c

U1950 pin 7 = 1.070v pin 3 between 55 and 58Mv
All_sys_pwrgdm Moves around a lot up and down between 130 and 180 Mv
 
Anterweb

Anterweb

Member
Am I measuring something incorrectly? I deffinatly have fan spin! Also I just noticed that with just the board on the bench when connecting the magsafe it turns green when connected then quickly turns orange, isn't this odd behaviour with no battery attached?
 
2informaticos

2informaticos

Administrator
Staff member
You've said no voltage on L7520 (5V_S4).

Since Magsafe 2, light goes amber without battery.
It turns back to green with fully charged battery (100%).
 
Anterweb

Anterweb

Member
Did some playing around this morning, with the board on the bench I get no 5v readings at all except on one test point right next to L7520 that reads 5v but the coil dosent, put the board back into the mac wire it all up hit the power button fan spins and I get 5v readings on the coil and 5v_s4 and 5v_so but as before no chime no display
 
Anterweb

Anterweb

Member
I have USB Power but don't seem to get any activity light flicker on either port,

As for the battery charging, I have it plugged in now with the charger light orange, is there any other way of knowing if it is actually charging without just waiting to see if the light turns green?

Magsafe feels warm like it's pulling Amps
 
Anterweb

Anterweb

Member
I can confirm it is charging the battery, MagSafe just turned Green after 2 hours ish of charging,

For checking USB activity I use an external HD with a working OS on it, Testing it on other working machines I get blinking light on the external HD when powering on the machine, Is this a a viable way of checking USB activity?
 
2informaticos

2informaticos

Administrator
Staff member
That's the best way for USB activity test.

About battery charging, just monitor PPBUS_G3H few seconds, when Magsafe light is amber.
It must slowly increase, when battery is charging.

Be sure to get all voltages from page 11.
Also check SPI Bus Series Termination resistors and traces; clean/remove J6100.
Try known good BIOS.
 
Anterweb

Anterweb

Member
Got the board under the scope and tested J6100 was going to try cleaning / removing but it looks in perfect condition so started testing voltages from page 11,

starting from top left and working down that column all test perfect 3.33v until I get to C1208 reading 188.7mv,then
C1220- 0v
C1212- .222v
C1214-.213v
C1250 -03.6mv
C1255 -0v
C1260 -59.1mv
and so on,

Have we found the area that the problem lies or is this a similar issue as happened above where I was getting incorrect readings with the board on the bench and not powered on back in the Mac?
 
Anterweb

Anterweb

Member
With the board in the mac and fan spinning I am getting 3V3_S0 and 1V05_S0 but checking the coils, all present and correct except for L3095 reading 0v
 
Anterweb

Anterweb

Member
Just tried the board on the desk with fan connected and no It has NO fan spin at all and just Mv readings on 3V3_S0 and 0v on 1V05_S0
 
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