Macbook Pro A1989 820-00850-a not powering on

**mon2** · 03-26-2022, 02:35 PM

Re: Macbook Pro A1989 820-00850-a not powering on

Remove all power.

Meter in lowest resistance mode (2k is ok).

Measure the resistance to ground of:

PP20V_USBC_XA_VBUS (Pin #1 of F3000)

PP20V_USBC_XB_VBUS (Pin # 1 of F3001)

Post the readings.

Diode D3370 - can remove it and test the part out of circuit to be sure of the condition of this component. Use Diode mode of your meter to test.

Without Diode D3370 - do you have the 5v on Vbus rails ?

PP1V1_UPC_XA_LDO_BMC - are not working on either ACE controller and this rail is required for the BMC power delivery communication with the Type C adapter. Just a FYI but for now, need the 5 volts (default output of the power adapter) to be stable on each ACE controller.

**Simplebeans** · 03-26-2022, 03:34 PM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

Remove all power.

Meter in lowest resistance mode (2k is ok).

Measure the resistance to ground of:

PP20V_USBC_XA_VBUS (Pin #1 of F3000)

PP20V_USBC_XB_VBUS (Pin # 1 of F3001)

Post the readings.

Diode D3370 - can remove it and test the part out of circuit to be sure of the condition of this component. Use Diode mode of your meter to test.

Without Diode D3370 - do you have the 5v on Vbus rails ?

PP1V1_UPC_XA_LDO_BMC - are not working on either ACE controller and this rail is required for the BMC power delivery communication with the Type C adapter. Just a FYI but for now, need the 5 volts (default output of the power adapter) to be stable on each ACE controller.

Hey mon2 i tried to measure at 2K resistance mode but that was producing a 0L reading for F3000 so tested it at by placing meter in resistance mode (200K) black probe to ground point and red probe to PIN #1:

PP20V_USBC_XA_VBUS measured 58.6KΩ (Pin #1 of F3000)

I then attempted to test at 200K but that was producing a 0L reading for F3001 so i tested that one by placing the meter in resistance mode (2M)

PP20V_USBC_XB_VBUS measured 0.191MΩ (Pin #1 of F3001)

I will go ahead and remove the Diode D3370 but there is one more issue i am have, the board is still stitting in the chassis and the reason for this is i stripped the screw heads for the two very small T3 Torx Screws that hold the aluminum cover over the display board flex cable.

Any tips or tricks/information on how it would be possible to get these screws out at all?

**mon2** · 03-26-2022, 03:44 PM

Re: Macbook Pro A1989 820-00850-a not powering on

Yes, invest in the proper tools. They are commonly available on Aliexpress.

You should be able to remove the stripped screws with the proper flat head screwdriver or perhaps a robertson head tip. You will have to experiment.

Worst case - use needle nose pliers but be prepared to damage surrounding parts that may be nearby.

Best to have the proper tools before starting.

**Simplebeans** · 03-26-2022, 03:48 PM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

Yes, invest in the proper tools. They are commonly available on Aliexpress.

You should be able to remove the stripped screws with the proper flat head screwdriver or perhaps a robertson head tip. You will have to experiment.

Worst case - use needle nose pliers but be prepared to damage surrounding parts that may be nearby.

Best to have the proper tools before starting.

And thats the thing mon2, I have got the iFix Mako Precision Bit Set with the correct T3 Torx screw driver, which is exactly what i used for this.

The other T3 screws i managed to get them out just fine i.e the four T3 Torx screws securing the plastic covers on top of the display hinges.

These did not want to come out.

**Simplebeans** · 03-27-2022, 05:17 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by Simplebeans

Hey mon2 i tried to measure at 2K resistance mode but that was producing a 0L reading for F3000 so tested it at by placing meter in resistance mode (200K) black probe to ground point and red probe to PIN #1:

PP20V_USBC_XA_VBUS measured 58.6KΩ (Pin #1 of F3000)

I then attempted to test at 200K but that was producing a 0L reading for F3001 so i tested that one by placing the meter in resistance mode (2M)

PP20V_USBC_XB_VBUS measured 0.191MΩ (Pin #1 of F3001)

I will go ahead and remove the Diode D3370 but there is one more issue i am have, the board is still stitting in the chassis and the reason for this is i stripped the screw heads for the two very small T3 Torx Screws that hold the aluminum cover over the display board flex cable.

Any tips or tricks/information on how it would be possible to get these screws out at all?

Hey mon2 i got the logic board out of the chassis, for anyone wondering what I did, I used a Torx T5 screwdriver (bigger size) so it filled out the stripped head and pressed down firmly to get a better grip and voilà! Both screws came out.

I desoldered the Diode D3370 off and plugged in my USB tester and now it will remain on 5V for a few seconds and then go to 20V and show amps being drawn.

I decided to put it all back together and connect everythng up by putting the logic board back into the chassis, just to make sure, and apple logo on screen! I am getting full fan spin so I will need to look into that but the machine is powering on now.

Does anyone have a spare D3370 diode or point me in the right direction as to where i am able to purchase this one?

Another thing which was strange was with the diode off the logic board i tried again to measure U3200 for signal PP20V_USBC_XB_VBUS at capacitor C3201 (PIN #1) but this time i was getting no voltage reading on the meter, i found that a bit of a odd one.

**mon2** · 03-27-2022, 08:26 AM

Re: Macbook Pro A1989 820-00850-a not powering on

NSR20F40NXT5G

https://www.aliexpress.com/wholesale...psort=1&page=1

https://www.mouser.com/ProductDetail...=NSR20F40NXT5G

https://lcsc.com/product-detail/Scho..._medium=buyNow

**Simplebeans** · 03-28-2022, 04:09 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

NSR20F40NXT5G

https://www.aliexpress.com/wholesale...psort=1&page=1

https://www.mouser.com/ProductDetail...=NSR20F40NXT5G

https://lcsc.com/product-detail/Scho..._medium=buyNow

Cheers mon2, I appreciate that.

**Simplebeans** · 03-31-2022, 11:47 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

NSR20F40NXT5G

https://www.aliexpress.com/wholesale...psort=1&page=1

https://www.mouser.com/ProductDetail...=NSR20F40NXT5G

https://lcsc.com/product-detail/Scho..._medium=buyNow

Hey mon2, the saga continues...

I replaced Diode D3370 today onto the logic board and now I’m observing some different behaviors. CD3215 - U3200 is not taking any power at all, so, when i plug in the USB-C Charge Cable into the USB port associated with U3200 the USB tester shows me no voltage (so the USB tester will not turn on). I tested the signal at PP20V_USBC_XB_VBUS to clarify this by placing black probe to ground point and red probe at PIN #1 on C3201 (multi meter in voltage mode 200V) and i get 0V.

Now the other three CD3215's -U3100, UB300 & UB400 my USB tester is displaying fine and shows 5.21V - 0.25amps. I also measured the associated signals @ PP20V_USBC_XA_VBUS, PP20V_USBC_TA_VBUS, PP20V_USBC_TB_VBUS and all of them are measuring 5.1V so those ACE controllers are getting power.

To make sure the USB port was not bad i connected the USB-C Board over onto the other side of the logic board JB500 (FPC connector) and now when plugging in the USB-C Charge cable both ports are showing on the USB tester 5.21V - 0.25amps. So the ports on the USB-C Board are ok.

I am now thinking then this, might be on, now the U3200 actually being bad. What are your thoughts?

Is there anything else i should be checking for?

Oh gosh, i love under fill.

**mon2** · 03-31-2022, 01:27 PM

Re: Macbook Pro A1989 820-00850-a not powering on

Remove this diode and test again (without the diode).

Respectively, this diode has a polarity. Please be sure it is being soldered in properly onto the board.

Attached Files

**Simplebeans** · 03-31-2022, 03:49 PM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

Remove this diode and test again (without the diode).

Respectively, this diode has a polarity. Please be sure it is being soldered in properly onto the board.

I checked the diode polarity and also followed the position of the solder pads, one pad being larger than the other. So thats the orientation i'd used. Also to confirm when I had put the Diode onto the board, the Anode was attached to ground pad, (bigger pad) and the Cathode, attached to the PP20V_USBC_XB_VBUS side pad (smaller pad). Although do correct me if i am wrong on this?

I have removed the D3370 Diode as suggested and now the USB port connected to U3200 is working again, when plugging in the USB-C Charge cable the USB tester is turning on and showing 5.21V - 0.25amps., even better still i tested again PP20V_USBC_XB_VBUS at PIN #1 on C3201 and it is showing now 5.1V! However it does fail to negotiate 20V, stranger even more still was the first 2-3 times i plugged in the USB-C Charge cable after removing the Diode it did get to 20V but did take a while time wise to negotiate to this from 5V.

And after checking now again for PP1V1_UPC_XB_LDO_BMC that has also come alive, so measuring it getting now 1.1V at Capacitor C3204 at PIN #1.

**mon2** · 03-31-2022, 06:50 PM

Re: Macbook Pro A1989 820-00850-a not powering on

Remove all power.

Meter in diode mode.

Red meter lead (yes Red), to ground.

Black meter lead to each ldo on the ACE controller. Post the diode readings for each rail of the cd3215 device.

Do this for each ACE controller.

**Simplebeans** · 04-01-2022, 05:44 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

Remove all power.

Meter in diode mode.

Red meter lead (yes Red), to ground.

Black meter lead to each ldo on the ACE controller. Post the diode readings for each rail of the cd3215 device.

Do this for each ACE controller.

Hey mon2

CD3215's (ACE controller) diode measurements:

U3100
PP3V3_UPC_XA_LDO measured at C3108 PIN #1 - .521
PP1V8_UPC_XA_LDOA measured at C3106 PIN #1 - .539
PP1V8_UPC_XA_LDOD measured at C3105 PIN #1 - .501
PP1V1_UPC_XA_LDO_BMC measured at C3104 PIN #1 - .532

U3200
PP3V3_UPC_XB_LDO measured at C3208 PIN #1 - .521
PP1V8_UPC_XB_LDOA measured at C3206 PIN #1 - .538
PP1V8_UPC_XB_LDOD measured at C3205 PIN #1 - .499
PP1V1_UPC_XB_LDO_BMC measured at C3204 PIN #1 - .533

UB300
PP3V3_UPC_TA_LDO measured at C3208 PIN #1 - .522
PP1V8_UPC_TA_LDOA measured at CB306 PIN #1 - .539
PP1V8_UPC_TA_LDOD measured at CB305 PIN #1 - .500
PP1V1_UPC_TA_LDO_BMC measured at CB304 PIN #1 - .532

UB400
PP3V3_UPC_TB_LDO measured at CB408 PIN #1 - .521
PP1V8_UPC_TB_LDOA measured at CB406 PIN #1 - .537
PP1V8_UPC_TB_LDOD measured at CB405 PIN #1 - 499
PP1V1_UPC_TB_LDO_BMC measured at CB404 PIN #1 - .531

**mon2** · 04-01-2022, 06:01 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Diode values look ok.

Meter in voltage mode.

Check the voltage of each ldo rail for the cd3215 that is being used to power the board.

Post the voltage readings.

Do any of the ports, even with if flipped around, allow for 20v ?

Suggest to only move the ports and cable when adapter is OFF (unplugged).

**Simplebeans** · 04-01-2022, 09:01 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

Diode values look ok.

Meter in voltage mode.

Check the voltage of each ldo rail for the cd3215 that is being used to power the board.

Post the voltage readings.

Do any of the ports, even with if flipped around, allow for 20v ?

Suggest to only move the ports and cable when adapter is OFF (unplugged).

CD3215's voltage measurements:

U3100
PP3V3_UPC_XA_LDO measured at C3108 PIN #1 - .3.3V
PP1V8_UPC_XA_LDOA measured at C3106 PIN #1 - 1.7V
PP1V8_UPC_XA_LDOD measured at C3105 PIN #1 - 1.7V
PP1V1_UPC_XA_LDO_BMC measured at C3104 PIN #1 - 1.1V

U3200
PP3V3_UPC_XB_LDO measured at C3208 PIN #1 - 3.3V
PP1V8_UPC_XB_LDOA measured at C3206 PIN #1 - 1.7V
PP1V8_UPC_XB_LDOD measured at C3205 PIN #1 - 1.7V
PP1V1_UPC_XB_LDO_BMC measured at C3204 PIN #1 - 1.1V

UB300
PP3V3_UPC_TA_LDO measured at CB308 PIN #1 - 3.3V
PP1V8_UPC_TA_LDOA measured at CB306 PIN #1 - 1.7V
PP1V8_UPC_TA_LDOD measured at CB305 PIN #1 - 1.7V
PP1V1_UPC_TA_LDO_BMC measured at CB304 PIN #1 - 1.1V

UB400
PP3V3_UPC_TB_LDO measured at CB408 PIN #1 - 3.3V
PP1V8_UPC_TB_LDOA measured at CB406 PIN #1 - 1.7V
PP1V8_UPC_TB_LDOD measured at CB405 PIN #1 - 1.8V
PP1V1_UPC_TB_LDO_BMC measured at CB404 PIN #1 - 1.1V

Originally posted by mon2

Do any of the ports, even with if flipped around, allow for 20v ?

And was not sure what you meant here about flipping them around? If you did mean taking the USB-C Board and connecting to both sides of the logic board at J3300 & JB500 (FPC connectors) i had to do this to perform the voltage tests above and none of the CD3215's were negotiating 20V.

**mon2** · 04-01-2022, 09:07 AM

Re: Macbook Pro A1989 820-00850-a not powering on

LDO rails look fine.

Do any of the ports enable the 20v selection ?

Try flipping the Type C power cable upside down for testing.

Suggest to ONLY move the ports and cable when adapter is OFF (unplugged).

There is too much risk in cross-shorting the CCx lines against the Vbus. These ACE controllers are dying out in the field for a reason...

Update - just saw your update. Thanks.

What I meant was the the Type C connector on the power supply is flippable. There is the TOP SIDE of the blade connector and theire is a BOTTOM SIDE of the blade connector.

The power delivery interface makes use of the CC1 pin on one side and CC2 pin on the other side. So if you have attempted the power connection one way, remove it and flip it upside down and mate again. We only want to confirm if the results are the same, using BOTH sides of the blade.

Suggestion again to remove the power adapter -> mate the connector to the logic board -> power up again.

**Simplebeans** · 04-01-2022, 09:23 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

LDO rails look fine.

Do any of the ports enable the 20v selection ?

Try flipping the Type C power cable upside down for testing.

Suggest to ONLY move the ports and cable when adapter is OFF (unplugged).

There is too much risk in cross-shorting the CCx lines against the Vbus. These ACE controllers are dying out in the field for a reason...

Update - just saw your update. Thanks.

What I meant was the the Type C connector on the power supply is flippable. There is the TOP SIDE of the blade connector and theire is a BOTTOM SIDE of the blade connector.

The power delivery interface makes use of the CC1 pin on one side and CC2 pin on the other side. So if you have attempted the power connection one way, remove it and flip it upside down and mate again. We only want to confirm if the results are the same, using BOTH sides of the blade.

Suggestion again to remove the power adapter -> mate the connector to the logic board -> power up again.

I see what you mean now, the USB-C Charge cable from the 61W USB-C Power Adapter, so i plugged that in one way inot the USB port, and then turned it 180° and plugged in the other way and the USB meter shows me 5.21V both ways. That is tested on all 4 USB ports.

**mon2** · 04-01-2022, 09:57 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Ok. What is the voltage of PPBUS_G3H with the power adapter connected ?

You can measure @ F7000, pin # 2. When the external power adapter is @ 5V (starting voltage by default), U7000 will become a BOOST regulator and boost the voltage to a higher value than the input (5 volts for your case).

Once the 20V power delivery contract is negotiated and selected, U7000 will then become a BUCK regulator (will lower the 20V to the proper PPBUS_G3H voltage).

**Simplebeans** · 04-01-2022, 10:06 AM

Re: Macbook Pro A1989 820-00850-a not powering on

Originally posted by mon2

Ok. What is the voltage of PPBUS_G3H with the power adapter connected ?

You can measure @ F7000, pin # 2. When the external power adapter is @ 5V (starting voltage by default), U7000 will become a BOOST regulator and boost the voltage to a higher value than the input (5 volts for your case).

Once the 20V power delivery contract is negotiated and selected, U7000 will then become a BUCK regulator (will lower the 20V to the proper PPBUS_G3H voltage).

I measured PPBUS_G3H @ F7000 PIN #2 (meter in voltage mode 20V) black probe to ground point and red probe to Fuse F7000 PIN #2 and i am getting a reading of 12.29V, however when holding the probes at the position i do see the voltage fluctuating between 11.60V then back to 12.29V, this is not happening all the time and not in any regular timing just randomly.

Oooo it fancy how this one Boosts and Bucks!

**mon2** · 04-01-2022, 10:08 AM

Re: Macbook Pro A1989 820-00850-a not powering on

The voltage of PPBUS_G3H should not be fluctuating.

Power down and desolder F7000 fuse. Then power up again and confirm if PPBUS_G3H is stable by measuring @ F7000, pad # 1 (fuse will not be in the circuit so there is no load from the consumer side of the circuit).

Macbook Pro A1989 820-00850-a not powering on

Macbook Pro A1989 820-00850-a not powering on

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Related Topics