P5VUSBC01_EN_R yes this one NO VOLTAGE PRESENT on this area.
CF840 = 1.8Volts Present
CF840 = 1.8Volts Present
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UF840 is a dual input AND gate.
Output of this dual input AND gate = 1 ONLY if BOTH inputs are logic '1'. Output will be a logic '0' = 0v otherwise.
Test the inputs to this dual input and gate. Measure their voltage to ground.
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OMG. I think I just fixed it with this... HOLD On. I replaced UF840 and that brought voltage and the meter is reading differently now. The amps jumped up a little.
I am now getting 0.26volts at P5VUSBC01_EN_R
UPDATE: jumped to soon. I am getting .26vols at that area now but still getting 20volts 0.00 amps. I think we are making progress.Last edited by Stephen; 04-16-2025, 02:46 PM.sigpic
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No, this has to be a logic '1' but note that the Vcc rail for UF840 is 1v8 so the voltage at the output = P5VUSBC01_EN_R should be ~1v8 or close to this if it is working correctly. If the voltage is lower, then confirm the 2 x input pins to this AND gate.Comment
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I see. Then I am not getting 1.8Volts on UPC01_5V_EN. No voltage present at RF840 either Suspecting that the USBC chips could be faulty?Originally posted by mon2 View Postsigpic
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Perhaps. Review each of the LDO rails on UF500 (CD3217) but mate the power adapter onto the physical port that uses this PD controller. Each LDO rail must be present on this CD3217.Comment
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LDO Present on CF508 (3.3v)
LDO Present on CG505 (1.5v)sigpic
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LDO Present on CF505 (1.5v)
What is the voltage of USBC1_3V3LDO_EN?Comment
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USBC1_3V3LDO_EN - Not Present. 0 voltssigpic
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Remove all power. Meter in DIODE mode.
Red meter probe to ground.
Black meter probe to point to test.
Test USBC1_CC1 in DIODE mode.
Test USBC1_CC2 in DIODE mode. Post each measurement.Comment
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USBC1_CC1 = 0.43V
USBC1_CC2 = 0.43vsigpic
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Try testing with another known good flash rom @ UF360. Be sure the SPI lines from the flash are reaching the local CD3217 @ UF500 through the series resistors of ~15R ohms each. It appears that each CD3217 onboard has its own local SPI flash rom. Suggest to use the same rom from a known good donor board from the same location on the donor board as this non-working board.
For giggles, you can review if you have a missing same signal on another board. Is the fault the same there as well?Comment
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I am going to try that. The customer is coming in today to get the DATA pulled first before I do any more repair attempts. We are going to put them in an identical MacBook Pro 14" we have in stock and copy their DATA over so we can work on this on our own time so we can diagnose without pressure. I will replace that next today once we take care of them. Thanks for all your help mon! I will be back here with an updater trying that out. This issue is pretty unique and I would love to solve it so we know what to do next moving forward if we get this type of repair again.sigpic
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Hey mon2 you will lose your damn mind over this board on what I just discovered. So battery charging issue right, board powers on, after a week of trial and error someone started to rear their head...a stupid SPEAKER amp chip reared its head and was preventing the computer from charging. This is a update for the books. So I replaced the speaker amp, and then the computer started finally charging. I DO NOT know why this would be a result but something tells me it is linked to PPBUS_AON and the amount of power it's getting. I replaced that stupid speaker amp and I got 20volts and .3amps (originally it would only get 20volts but 0.00amps) without a battery and it finally starting showing life. I replaced a CD3217B12 that was damaged but that didn't solve the charge issue so I kept looking and on the thermal camera one of the speaker amps was getting hot (92 degrees) So I was like WTH? Replaced it and the board didn't do anything at first...but the short went away...after it cooled down and it decided to work...still testing but I think I found the issue.Last edited by Stephen; 04-18-2025, 03:12 PM.sigpic
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Very nice find! About 2 weeks ago, had a student bring in an A1932 (I believe, have pics to confirm later) which other shops including Apple stated as a no fix. Found the issue was linked to a shorted cap on the headphone board that is fitted away from the main logic board BUT powered by the same ppbus_aon rail. In our case, the resistance to ground was 1 ohms when he brought it in on ppbus_aon -> after we injected with 'short killer tool' -> raised to 14R ohms. We truly thought the CPU is dead and took it all apart for the thermal camera inspection. Bingo, the ppbus_aon rail was magically at a high resistance. What did we do? Nothing other than disconnect all cables and screws. After another few minutes of toying with the permutation -> the headphone board was 100% guilty. The tiny board sells for ~$100 on the market. No thanks!! Found the schematic for the board and noted that 5 caps are linked to the ppbus_aon that is fed from the main board. After the 3rd cap removal -> short was gone. Student was super happy since he needed his data off the solid state and soldered drives.
Good job and yes, will be helpful to future readers.Comment
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My post is being censored again. See attached.
Wait till I start my 'Only Fans' channel...
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Lol I may start one as well. It will be "Logic Board Screws me hard" and my favorite "My logic board is wet"
Also although that IC Amp chip was somewhat the culprit, I did find two faulty resistors on the board RF508 and RF509 was not letting the battery become recognized. The resistors were not bad but they were not soldered down all the way to due corrosion. I replaced them and now it charges fully. Just glad I figured this one out, hopefully with this info I can repair the final 3 pretty quickly.sigpic
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So I discovered some new knowledge or maybe its not new who knows. These computers seem to boot when the USB C chip is somewhat faulty, even if the resistors are good, replacing a faulty CD3217B12 chip will result in the voltage to jump back up to 20Volts and proper amps for charging the battery. I noticed this with each board yet all of them had the same issue, some had different chips to pinpoint. But most of them all resulted in a CD3217B12 chip being swapped out from a donor. I solved two boards and both had faulty CD3217B12 chips. I. had to source a donor board since I know that the 14" those chips need to come from the correct side just like A2251 boards. One board had a faulty CD3217B12 chip but was still registering so the computer turned on, With this knowledge I was able to solved the second one, I am waiting on another donor for the third. The other board had heavy liquid damage near the HDMI port which hit the CD3217B12 chip. Replacing these more than likely solves the charging issue even though it turns on with a battery....
Update: my assumption was correct. CD3217B12 chips are the culprit in this type of issue. ONE thing I did notice and I want to give knowledge about is when all CD3217B12 is working you would get 5volts but what I discovered is if you plug up the meter and test PPBUS_AON you will get 12volts on most chips, but one board in particular would give you a different reading if you plug it into different ports. Example: USB C port UF500 would result in 12volts on PPBUS_AON but had 5 volts as usual, plugged up the meter to UF400 same result, Plugged up the meter to UG400 5 volts per usual HOWEVER, PPBUS_AON would result in voltage reading under 10 volts. I was suspicious so I replaced it and voila the board turned on and started getting amps again, plugged up battery and then the battery finally charged.
Hopefully this helps someone in the future.Last edited by Stephen; Yesterday, 01:12 PM.sigpic
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