To me, the fault appears to be a mechanical issue with the dcin power jack.
Leave PL102 off the board. Attach the power adapter but do not plug into the ac wall socket.
Test the center pin in diode mode using the PL102 pcb pad. What is the measurement?
mon2
Badcaps Legend
Last Activity: Today, 05:39 AM
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Location: Windsor, Ontario
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You can use 1k to 2k2 on these resistors which are very likely to be pull-ups as required by the I2C specification.
See attached (from other ipad schematics)
[ATTACH=JSON]{"data-align":"none","data-size":"medium","data-attachmentid":3527927}[/ATTACH]...Leave a comment:
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Yes, you will definitely require hot air tools + tweezers + flux. This combination of tools will then melt the solder that is under this mosfet (including the belly side solder). Only then can the tweezers pluck the part of the board properly. Be sure to watch YT videos on the topic and be patient. Test on donor boards before removing this part. Too much heat will burn the board. Too little heat will not allow for the removal nor soldering. To high air pressure will send the nearby SMD parts into the next dimension. Each parameter must be balanced.
Also, be care to not tear the PCB...Leave a comment:
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Yeah, I am afraid not good news. Respectively, this high voltage must have hit the CPU vcore rail.Leave a comment:
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V9B+ is from the charger IC. It is taking in the ~20v from the power adapter and lowering to this voltage. The resistance to ground is very much of concern.
Remove all power.
Meter in resistance mode. Check the resistance from this same V9B+ rail (place one meter lead here) and the other meter lead onto the VCORE cpu power rail. We are checking the resistance between these 2 points. If the resistance is low, then the high side mosfet on the VCORE rail has leaked and injected this very high voltage onto the CPU.
Share the resistance measured between these...Leave a comment:
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Try a DFU to the unit.Leave a comment:
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No. Not necessary. If I recall correctly, some motherboards and perhaps this one, will only boot if there is a pre-charged battery mated with the board. You are in the valid range for PPBUS_AON.
So what is wrong with this unit? Allow for the usual time to boot to login screen and then press the keycaps key. Do you see the caps key led toggle on/off after a keypress? If yes, the board is booting and you are the login screen.
If not, carefully, measure the voltage to ground on each and every inductor on the board. Each inductor is linked to a local power supply rail that...Leave a comment:
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At 12v, the PPBUS_AON is not boosted to the normal ~13v level. This 13v level is selected using the I2C / SMBUS interface (SCL / SDA lines).
[U][B]Remove all power. Disconnect the battery @ J5150.[/B][/U] Meter in resistance mode.
Measure the resistance to ground of the SMBUS lines (SCL / SDA). One meter probe on the pin to test. Other probe to ground. What is the resistance?
We are checking if either of the TVS diodes that mates with the SMBUS lines is defective or not. If yes, this can shunt the communication lines used by the ISL9240 buck boost regulator...Leave a comment:
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Ok. This confirms that each of your CD321x PD controllers are working since you have 20v negotiated with the external type C power adapter. Good.
Carefully, measure the voltage to ground of [B]PPBUS_AON [/B]@ fuse F5200. Check both sides of this fuse. This is a critical main power rail for the board. What is the voltage to ground? This is like the older [B]PPBUS_G3H [/B]power rail.Ok. This confirms that each of your CD321x PD controllers are working since you have 20v negotiated with the external type C power adapter. Good.
Carefully, measure the voltage to ground ofLeave a comment:
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Diode mode testing is different than resistance mode testing. The shared diode mode measurements make it clear that this part is defective.Leave a comment:
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Use only resistance mode. What is the resistance in ohms? 5 ohms? Definitely shorted. Each resistance check should be hundreds of k ohms or higher if the part is not defective. Seek out a replacement. They are cheap and commonly found on most motherboards. Share the topside markings of this and also the replacement parts for a quick review. BQ chargers will often use N-channel 30v rated mosfets (5x6 size). No power to the board (only to the people) when using resistance or diode mode checks.Leave a comment:
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Is the Vcc to the EC (IT8227E) stable? Is the EC heating up - more than normal? The EC also has its own firmware driven by the SPI bus where the EC is the bus master. If you have the spare working board, consider to swap out the flash device @ U2 (Bono?) used by the EC for testing.Leave a comment:
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2R2 to ground on the 3v3 rail? Yes, that is far too low. Wait on other comments but based on the fact that the PCH is heating up, this is a dead end case.Leave a comment:
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Hi. No. The above is for the older macbook models. The A2337 is the pain in the arse, M1 design. This unit operates with USB power delivery. There are plenty of details of this model here and repairwiki, etc.
Start with the using only a suitable rated power adapter. 100W with 100W rated power cable is recommended if the original power adapter is not available. Place a USB Type C meter (bidirectional type) in the middle of this power adapter and your logic board. This meter will tell you if the power delivery chips on the logic board are working or not. If you do not have 20V, this...Leave a comment:
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Yes, it appears to be the case.
With no power to the board, what is the resistance to ground of the missing 3v3 rail? This rail, as you noted, is powering the PCH and also the bios, etc....Leave a comment:
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Go upstream on the power rails. Who is stable?
Is the voltage to ground @ V9B+ stable or also power cycling ever 3 seconds?
This is the primary power rail to power the logic board. It may be that the power cycling is occuring due to an excessive current draw or some regulator believing that there is a higher than normal current draw so the regulator is in chirp mode (on/off/on..). This issue can surface if there is a break in the current sense loop of the power rail being monitored.
Start with the main power rail for the measurement. Perhaps the bios is corrupt...Leave a comment:
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Hi and welcome.
1) Review the sticky above by [USER="169897"]piernov[/USER].
2) Unable to find schematics for this exact board but the board in front of you should be helpful. Hunt for the charger IC that should be nearby the DCin power jack. Often, HP boards wll feature the DCin jack followed by 2 x DCin mosfets and then the charger IC. The charger IC is often the 'BQ' series so look for this topside markings. It will be a square IC. Share the full topside markings of this IC. Once found, then the datasheet or other similar reference schematics will help to...Leave a comment:
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Repost this thread inside of the dedicated bios section. Someone there will be able to assist you.Leave a comment:
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There is the possibility that the mosfet is defective and therefore reporting the same 'OL' resistance. Test against another known good mosfet to compare.Leave a comment:
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Yes, 10k pull-ups are perfectly safe to place onto the pads you have shared.Leave a comment:
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