This one is dead. I get 12V from 4 pins on power supply to board. Is center pin of the powersupply connector supposed to have any power? No fan spin or chime. I have 3v3_s5 and nothing at what I believe is the PP5V_S4 coil. Diode on that coil is .402 and diode check around U7501 seem to be comparable to 820-3662 board. No signs of liquid and nothing noticeably bad on board. CHecked to see if maybe any caps loose (if it were dropped or something) but best guess is maybe supposed to be voltage from center pin on the power supply and that is issue....
-
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
2014 Mac Mini
- Thread starter grmacs
- Start date
Unfortunately, no schematics available for Minis.
Do you note any pulse at big coils?
Check at the same time when press the power button.
Do you note any pulse at big coils?
Check at the same time when press the power button.
No pulses at other large coils with power button, just steady 3.3V on the one. So I take it no voltage at middle pin of power supply connector is normal? I did verify that the power button closes the circuit correctly so it works at least. I tried SMC bypass just to see but guessing wont work on a mini...
Check for short on the 5V USB power rail.
Shorted caps there is classic issue...
Shorted caps there is classic issue...
No luck on those but was a good thought. Not seeing familiar PP3V42 components but I do have dropping values around the SMC. Any idea if this board should have PP3V42_G3H? Some spots I'm getting 3.38V but I think that is actually PP3V3_S5... If the dropping voltage measurements are supposed to be PP3V42, that would be my issue. Not seeing the familiar coil like whats on A1398 board or 00165. Most of the test points though around the SMC checking with diode are around .712 range... not sure if that could be a tell of any sort. Not shorts though anyway
Last edited:
You can't get 3V3_S5 without 3V42_G3H; so that's not the issue.
Lift that coil one side and see where the short remains.
What is the exact ohm resistance of the short?
Lift that coil one side and see where the short remains.
What is the exact ohm resistance of the short?
Just in case, remove RAM and check again.
Could be CPU; can confirm after coil is lifted.
Could be CPU; can confirm after coil is lifted.
Not good... pulling that coil up, the short is CPU side and I pulled what looks like a R7640 and the leg of that that is shorted is the one that sends power to CPU. Pulled the caps from and resistors near there from that leg just on a hope and a prayer and the short is still there so it appears the short is in the CPU.
CPU VCORE may have very low value to ground.
But not low value for other CPU voltage, like PCH power.
But not low value for other CPU voltage, like PCH power.