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820-4924-a doesnt turn on - chimes

M

MegaObi

Member
Hey all i got a mbp which has strange issue. it chimes but doesn't turn on.
no history - no sign of droppage or liquid.

When i hold power button i get chime. fan doesnt spin and cpu gets very hot.

When i disconnect battery and press power button i get no chime and no sign of power.

ppbus_g3h is 12.68v
pp3v42_g3h 3.46v
ppvrtc_g3h 3.3

pp5v_s0 5v
pp3v3_s0 3.3v

pp1v2_s3_cpuddr 1.19v
pp1v2_s3 1.20v
pp1v8_s3 1.8v
pp1v5_s0 1.5v
pp1v05_s0 1.05v
ppvcc_s0_cpu 1.89v
 
2informaticos

2informaticos

Administrator
Staff member
If chimes, board turns on.
But you have another problem if nothing appears on the screen.

Fan doesn't spin from the beginning as normal behaviour on this model.

Use original Magsafe 2 60/85W charger.
Magsafe 1 --> 2 adapter is known to generate backlight issue.

Seems like your board only starts with battery.
Did you try to start in SMC bypass mode, on charger only?

Post U7100 voltage, pins 2, 3, 9, 15, 12, 13, 14, 26 (only charger connected).
Do you get 3V42 on charger mode (no battery)?
 
J

JohnB8812

New member
Your device is turning on with no image. Do you get a light on a USB mouse or any external video? The CPU getting super hot doesn't give much hope for this one.
 
M

MegaObi

Member
Hey informaticos pins for u7100
2- 16.77v
3- 3.99v
9- 0.02v
12- 3.45v
13- 3.13v
14- 3.13v
15- 0.04v
26- 14.37v

also pp3v42g3h present when only power connected (no battery)
 
2informaticos

2informaticos

Administrator
Staff member
OK, then Q7180 looks good.
Now post (only charger connected) PM_BATLOW_L, SMC_ADAPTER_EN, PM_SLP_SUS_L, 3V3_SUS, S5_PWRGD, PM_DSW_PWRGD, PCH_DSWVRMEN, PM_RSMRST_L.
Trigger SMC_ONOFF_L (R5115/16) and check for any reaction at PM_PWRBTN_L and PM_SLP_Sx_L signals...

Don't forget,
"Use original Magsafe 2 60/85W charger."
 
M

MegaObi

Member
hey informaticos thank you for your reply.
I am using original magsafe 2 60w charger.

I have
pm_batlow_l 3.3v
smc_adapter_en 3.4v
pm_slp_sus_l 3.35v
s5_pwrgd 3.4v
pm_dsw_pwrgd 3.4v
pch_dswvrmen 3.25v
pm_rsmrst_l 3.3v

Im not sure how to do this informaticos. "Trigger SMC_ONOFF_L (R5115/16) and check for any reaction at PM_PWRBTN_L and PM_SLP_Sx_L signals..." any additional help will be much appreciated.
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
"Trigger SMC_ONOFF_L (R5115/16) and check for any reaction at PM_PWRBTN_L and PM_SLP_Sx_L signals..."
Short R5115/16 pads, less than 1s, like pressing power button.
Better even, solder tiny wire on SMC_ONOFF_L and touch the ground...
 
2informaticos

2informaticos

Administrator
Staff member
If multimeter doesn't catch any pulse at least, then should be good to try witb an o-scope; it will catch any pulse.
Usually, multimeter is good enough; it should catch something, if you trigger SMC_ONOFF_L repeatedly...
 
M

MegaObi

Member
ok so its at 3.4v and when i short r5115 drops to .3v on PM_PWRBTN_L


PM_SLP_S5_L pulse should i test all PM_slp_sx lines?
 
2informaticos

2informaticos

Administrator
Staff member
Check them all.
PM_SLP_S4_L enables S3 state and PM_SLP_S3_L enables S0 state.
If pulse, check if controlled voltages pulse too.
 
M

MegaObi

Member
Ok please be patient with me. I am new to oscilloscope. So basically when i test the Pm_slp lines i get two types of reading - one is just an instant voltage change - this is when voltage just goes from 3.3v to 0 when i press power OR second type of reading i get is the voltage goes up and down in a very short 100-200ms <- is this what you mean by pulse?
 
2informaticos

2informaticos

Administrator
Staff member
PM_PWRBTN_L should drop to 0V and goes back to 3V instantly; after SMC_ONOFF_L is released.
All PM_SLP_Sx_L lines should go high and stay there.
At the same time, ALL_SYS_PWRGD must go high too.
For some reason all drop to 0V because of a power issue, I suppose.
You must check if all these try to go high at least.

If AL_SYS_PWRGD doesn't even pulse, SMC/PCH will stop the power sequence.
 
M

MegaObi

Member
the only time they drop to zero is when i hot smc_onoff_l otherwise all are high including all_sys_pwrgd

all_sys_pwrgd doesnt pulse always high.
 
2informaticos

2informaticos

Administrator
Staff member
If ALL_SYS_PWRGD stays high, you must have all the voltages present; maybe excepting CPU ones.
Please confirm which is your situation.
 
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