MacBook Pro 15" 2017 A1707 Touchbar No power

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

No worries. We are on similar paths. Have a painful A1706 that needs more love and trying to avoid it. Doing so without a microscope till the CNY.

Do post your DIODE readings as they may assist us in debugging this logic board.

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

The board never goes to 20V. It just gets to 5.20v then cycles off and repeats. I have replaced two CD32 chips, I guess I need to replace the other two as well. I have stenciled the other two and they came out great, Ill just replace those other two and reball them and put them back on the board and see what happens.
lol it just sucks because these CD32 are a bitch since there is 4 of them you have to do lol. Also I will look into buying that stuff as well. Ill keep you posted. This is just a board laying around. We threw it in our Crest Ultrasonic cleaner and it cleaned up very well, and still having issues so now we know its def in this area for sure. So far visually under the scope there are no lifted pads (THANK GOD). This may be a 2TB board with the max GPU upgrade and we really want to get this working because this is a very pricey board we want repaired. Other boards are pretty easy, but once we get to this level it starts getting down to problem solving again, ALSO thanks for your help mon2

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Which CD32xx USB controllers have been replaced?

When you attach a suitable power adapter, does the voltage ever negotiate to 20V?

Are you confident of your CD3215 replacement exercise?

From my (limited) knowledge, each CD3215 controller is required to be operational and has to ping back to the SMC controller over the I2C bus (SDA / SCL lines).

That is, the SMC controller will systematically communicate with each local controller over the I2C bus using their unique address and the respective controller is required to ping back a valid response.

Perhaps this communication is broken with one of more of the CD3215 controller. Or it is possible that the communication is ok and then the power negotiation is escalated to 20V and the unit powers down due to an excessive current draw and starts this looping cycle.

Have not personally attempted it but any chance you have a low cost USB based logic analyzer? They are < $20 USD on Amazon and < $5 USD on Aliexpress.

Using such a tool, you can solder 3 wires onto the macbook and snoop on the I2C bus traffic to monitor what the SMC is sending / receiving from each I2C slave.

Here is what I am referencing:

https://www.aliexpress.com/item/4000...archweb201603_

There are many others at lower costs.

You just need to find one that is available in the USA at a fair price.

We may be going down a rabbit hole here but am a strong believer that you need to the proper tool to diagnose such rather high tech devices.

Perhaps a better suggestion is to first check the wikipedia link:

https://logi.wiki/index.php/CD3215_Bootup_Sequence

and confirm the diode readings for the D+ / D- lines for each CD3215 port.

1) Place your multimeter in DIODE mode.
2) Turn OFF all power to this logic board.
3) RED (yes RED) meter lead to GROUND.
4) BLACK (yes BLACK) meter lead to the D+ line to a CD3215 port.

What is the reading?

5) BLACK (yes BLACK) meter lead to the D- line to a CD3215 port.

What is the reading?


Repeat the above steps (4 & 5) for each USB Type C port.

What are the readings for each probing?


If the readings are off then that local CD3215 controller may need to be replaced.

Please post your updates.

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Also if the resistor is brought back the line will fluctuate and loop.

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

When we bring back the resistor the board starts to turn off and on on the USB C meter. It basically starts the process over looping. It stopped when the resistor was removed

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

That is a high reading and that is fine. If you bring back the zero ohm resistor, this line starts to fluctuate or is it steady?

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Figures thanks
It starts at 40.00 M OHMS and drop and keeps dropping.

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Resistance and Diode values can only be measured with the unit powered OFF.

Kill the power and black probe to ground; RED probe onto pin 2 of this resistor pad that has been removed.

Wish to check the resistance along this rail to see if it is too low. Often too low of a reading implies a short circuit - either external due to corrosion or internal from some bad cap. Tantalum (black polarized ones) are usually the bad ones over time.

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

ok don't think I am dumb here. But I have it set to Resistance. But should i have the power plugged in for this or not? Because I get two readings doing it. Sounds dumb I know.

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

What is the reading of the value?

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

so further testing on pin 2 i am getting a reading and it keeps dropping.

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Left the shop, will post value first thing tomorrow!

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Yes, as per above.

What is the resistance to ground on pin 2 of the removed zero ohm resistor?

If the value is low, then you have probably have a bad cap on this rail.

Please post the value.

[MobileXT]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Try check on pin 2 R6923 for shorted.

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Removed the O OHM resistor. It is not power cycling anymore and I now have a 3.3v steady on PIN 1.

Remove the 0 ohm resistor @ R6923 and power up again.

What is the voltage out out on pin 1 of R6923 (without this series resistor)?

Do you see a steady 3v3 on this rail or still power cycles for this rail?

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Also our board is
820-00281-A

[Stephen]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Hey replaced a few CD32 and still same issue, Going to check this now.

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Check to confirm that the LDO_BMC value for EACH of the CD3215 is @ 1v1. This voltage rail powers the BMC communication for the USB power delivery handshakes.

Do review this very nice webpage on this subject:

https://logi.wiki/index.php/CD3215_Bootup_Sequence

The TBT (thunderbolt) controller apparently is required to communicate with each of the CD3215 controllers over the I2C bus. If something is wrong with this process, this may cause your cyclic booting.

Do check for any voltages on SMBUS_SMC_4_G3H_SCL and also SMBUS_SMC_4_G3H_SDA.

Any voltages? What are the values? If no activity, then I2C bus communication is not working.

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Also, from here:

https://logi.wiki/index.php/CD3215_Bootup_Sequence

See the following:

Satyrcon 11.12.2020

Issue: 820-00840 wont take anything from charger, either port, or orientation.

Visible inspection resulted in marks on CC1/2 pins on both USB-C ports.

Diode mode measurement showed ~0.550V on 3 of them, one ~0.040V.

Replacing the port fixed the issue.

Conclusion: One damaged CC pin can cause the whole lot to stop functioning.

Post your diode readings for the CC1 and CC2 pins on each of your USB Type C connectors. An incorrect reading on one or more could indicate a fault on that specific CD3215 controller. If found, you could attempt to just remove that CD3215 controller out of circuit to see if that makes a difference for the balance of the logic board. Be sure that no pads are removed in the process and that no pads are shorting after this removal process.

[mon2]

Re: MacBook Pro 15" 2017 A1707 Touchbar No power

Remove the 0 ohm resistor @ R6923 and power up again.

What is the voltage out out on pin 1 of R6923 (without this series resistor)?

Do you see a steady 3v3 on this rail or still power cycles for this rail?