Have a 3332 that gives a green light, then switches over to a faint orange light. No fan. PPBUS_G3H is reading at .7v at multiple points on the board. U7000 is new, all components around it check out fine. 20.25v off the io board. no blown fuses (of course). chrgr_dcin at u7000 is 20.25 pin 3 of u7000 is reading somewhere around 4.5v. Then suddenly, the charger only goes green, and shorts out and shuts off (to where I have to unplug it to reset it.)... any thoughts?
-
For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.Subscribe Now
3332 ppbus_g3h .7v
- Thread starter Rford
- Start date
1) What was the original issue? Liquid, knockoff charger, drop?
2) PP3V42_G3H present?
3) SMC_BC_ACOK present?
4) With no power applied, what is resistance between pins 17/18 and pins 27/28 of U7000?
5) With no power applied, what is the resistance to ground on PPBUS_G3H?
6) Is SMC_RESET_L present?
7) Does this behavior persist when all components are unplugged from the board?(keyboard, etc.)
2) PP3V42_G3H present?
3) SMC_BC_ACOK present?
4) With no power applied, what is resistance between pins 17/18 and pins 27/28 of U7000?
5) With no power applied, what is the resistance to ground on PPBUS_G3H?
6) Is SMC_RESET_L present?
7) Does this behavior persist when all components are unplugged from the board?(keyboard, etc.)
1. I suspect an after market charger.
2. present
3. 3.1v
4 4.1ohms and 21.2
5 .4 ohms
6. 3.3v
7. Board is out of the machine
There is no corrosion or anything that would suggest liquid damage. Pretty safe bet that the MagSafe is in fact MagShit.
You have a short to ground on PPBUS_G3H. Find it! Inject 1v and see if anything heats up. Measure for a short to ground between PPBUS_G3H and any of the PP3V3_S5/CPU VCORE output coils of course.
larossmann C7620 was shorted. Restored PPBUS_G3H Now quarter fan spin. No vcore. Checked around on vcore found bad R1360, switched it out for a good one. Same. Ideas? Vcore has a ton of componentry. In diode mode, vcore is 0.000 (shorted)
Last edited:
vcore is not shorted, tell me why.
larossmann You'll have to bear with me, but would it be because of where it originates (pp5v_s0)? and i dont have a good S0 pulse?PP5V_S0 Pulses from zero to between 1.5-3.3v every seven seconds. (It is the same as when each fan turns (though they never turn at the same time, or duration).
Last edited:
It's not a short.
These aren't exact numbers, just guessing, but let's say a CPU uses 45w of power.
Let's say a CPU runs on 1v of vcore.
What resistance to ground do you need in the ohm's law calculator to get 45w out of 1v? http://www.ohmslawcalculator.com/ohms-law-calculator Try it out.
Chips that use LOTS of wattage at low voltage will have a low resistance to ground, it is just natural. Same thing with a speaker. If you look at receivers where it says 100w into 8 ohm load, 175w into 4 ohm load. It is able to deliver more power/current at the same voltage if the resistance is lower. A 3 ohm speaker is essentially a 3 ohm "short" but that does not mean it is "broken."
These aren't exact numbers, just guessing, but let's say a CPU uses 45w of power.
Let's say a CPU runs on 1v of vcore.
What resistance to ground do you need in the ohm's law calculator to get 45w out of 1v? http://www.ohmslawcalculator.com/ohms-law-calculator Try it out.
Chips that use LOTS of wattage at low voltage will have a low resistance to ground, it is just natural. Same thing with a speaker. If you look at receivers where it says 100w into 8 ohm load, 175w into 4 ohm load. It is able to deliver more power/current at the same voltage if the resistance is lower. A 3 ohm speaker is essentially a 3 ohm "short" but that does not mean it is "broken."
You can also measure the ohm value you get when you short your multimeter leads: this is your dead short ohm value reference.
Now check resistance to ground on vcore and compare with your dead short reference.
You can also inject 0,5v on vcore, and see if you measure 0,5v with multimeter.
Now check resistance to ground on vcore and compare with your dead short reference.
You can also inject 0,5v on vcore, and see if you measure 0,5v with multimeter.