Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

[cyber47]

Hello,

i have used the search function but i doesnt found my problem.

I am reparing a MacBook Pro A1706 with the Boardnumber 820-00923-A.

If i have the display and/or the trackpad installed the Macbook does not boot, i have 20V and 0.03 Amps at the charger (without the battery connected), i can post a video of the Amperemeter if this helps.
The board has PPBUS_G3H and it seems it is in the S5 state (i have the voltage on the S5 rails but not on the S4 rails).

If i connect the charger without die display and the trackpad installed i get fanspin and 20V with 0.8A to 0.6A. Here is a video of the Ampmeter: https://youtu.be/73dbuSqg0cw (if it is not ok to link my video i will remove it )
Is this the normal boot behavior? If i connect a screen with usb-c to hdmi adapter i get no image.
Without the screen and the trackpad connected the board has all powerrails present.

I dont have a replacment screen or trackpad because i only repair MacBooks as a hobby.

The board looks very clean and no liquid damage or burned components are visible.

I hope the information are enough, please ask if a forgot something important.

Thank you for your help

Best regards

Cyber47 from Germany

[cyber47]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

Hello,

sorry for a second post but i have a update:
The Trackpad seems to work after i cleaned the connector again. I can feel the click now and from what i can see on the amperemeter the Board seems to boot, but i get no display on an external monitor, no chime and no green light on the shift-button. SMC seems to work because if i press the keyboard to perform an smc reset the amperemeter goes to 0A for a short time and up after that.

If i connect the internal display the board does not boot, it only draws around 20mA at 20V. I get only to state S5.

I am really bad with finding problems so any hint would be appreciated!

Thank you very much!

[dellxps15]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

try pram reset (command option p r ). check if it chime.

try usbc->vga or usbc-hdmi. if u plug power to usbc adapter use more then 67 watt charger
plug a usb flash drive with led and see if it blink.

if nothing happen. check lcd backlight cable if it has the common problem and maybe is shorting backlight to alluminium chassis.

focus first on make it work on external (internal not connected)
1° usb flash drive light blinking ?
2° pram reset ?
3° cpu get hot ?
according to ampere consumption ur pc is starting and booting.
if no image try dfu restore.

[cyber47]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

Hello,

thank you very much for your help

At first i have news about the board: i checked the connector on the display daughterboard and i have a short on PP5V_S0_ALSCAM_F on the daughterboard. I2C_CAM_SDA is very low resistant to ground on the mainboard and also on the daughterboard.
I have used capton tape to disconnect the two lines on the connector and the board seems to boot (or behaves like it boots) with the displayconnector in place but i have no PPVOUT_S0_LCDBKLT.

But you are right i will focus first on make it work on external display with the internal display not connected:

I used the original apple usb-c charger with 30W but i will test other chargers

I tried pram reset multiple times after you suggested it but i hear no chime, no external display and no light on the shift key.

1° usb flash drive light blinks every 10 seconds, so i think the mac tries to read the drive
2° pram reset does not make a difference
3° cpu gets hot and after a while the fans go on

I think a dfu restore is not possible with the A1706 Macbook Pro because i think it has no T2-security-Chip? If it is possible can you please link a guide or give me a hint how to do it? I only found guides for dfu restore for newer MacBook models.

Is there anything i can check to make sure the integrated gpu is working?

Thank you very much for your help again!

Have a nice day
Cyber47

[cyber47]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

Hello,

i have a little update:

1. I tested a charger with 100W but nothing changed.

2. I am missing PPVCCEDRAM_S0_CPU and after i followed the signal i found out that PPVCCEDRAM_S0_CPU is missing because CPU_ZVM_L is missing.
But CPU_ZVM_L is generated from the cpu, so i can nothing change here i think.
I dont know if the signal is necessary or if it should be present at all because in the schematic the signal is negated, if i read it right.

Can someone please help me to find out, if PPVCCEDRAM_S0_CPU should be present and if so if it prevents the board from turning on?

Any hint would be great

[DeCrybaby]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

Hello,

i have a little update:

1. I tested a charger with 100W but nothing changed.

2. I am missing PPVCCEDRAM_S0_CPU and after i followed the signal i found out that PPVCCEDRAM_S0_CPU is missing because CPU_ZVM_L is missing.
But CPU_ZVM_L is generated from the cpu, so i can nothing change here i think.
I dont know if the signal is necessary or if it should be present at all because in the schematic the signal is negated, if i read it right.

Can someone please help me to find out, if PPVCCEDRAM_S0_CPU should be present and if so if it prevents the board from turning on?

Any hint would be great

The PPVCCEDRAM_S0_REG_F should at pin 5 of U7760.
Did you check at L7700?

[cyber47]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

The PPVCCEDRAM_S0_REG_F should at pin 5 of U7760.
Did you check at L7700?

Hello,

thank you for your help!

I checked PPVCCEDRAM_S0_REG_F at pin 5 of U7760 and i have 1.05V

I also checked L7700, there i have also 1.05V.

I followed the Signal and it seems it is missing CPU_ZVM_L at pin 2 of U7790. As far as i know the "_L" means the signal is low in its "normal" state? But i have no second working board to confirm. Do you know if it should be present?

I checked all voltages that are on Power Aliases pages of the schematic and the only one missing is PPVCCEDRAM_S0_CPU, thats how i found that CPU_ZVM_L is missing. Are there any other signals or power rails i should check besides the ones on the Power Aliases pages in the schematic?

Thanks again for your help

Best regards

[dellxps15]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

bios still the original or u tried different bioses ?
if original keep it that way.

no apple logo on external ? both usb-c to hdmi or better usb-c to vga.

if u tried everithing , check if notebook is seen in dfu mode.

u can use a usb keyboard. just mainboard, usb-c hub and usb-c psu.

[cyber47]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

bios still the original or u tried different bioses ?
if original keep it that way.

no apple logo on external ? both usb-c to hdmi or better usb-c to vga.

if u tried everithing , check if notebook is seen in dfu mode.

u can use a usb keyboard. just mainboard, usb-c hub and usb-c psu.

Hello, sorry for the late reply!

Yes, as far as i know it is the original bios.

I have no apple logo on external, unfortunately i can only test usb-c to hdmi

Can you please give me a hint how i check for dfu mode on this model? i only find information about dfu mode for newer macBook Pros.

Thank you again for your help!

a little update: i found out, i have stable voltage of 1.046V at the PPVCC_S0_CPU and it is not dropping to 0.7V or something. Does this mean i have a bad cpu?

Best regards

[reformatt]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

There is no DFU mode on T1 MAC's, only T2. What is the history of this machine? Any prior work on it (perhaps liquid damaged and already been through an ultrasonic)? Are the liquid damage indicators present or removed? Red or white if present?

Pay close attention to the pins around U7100, looking for any corrosion etc. Measure resistance of each coil for the CPU to ground, especially near the edges (as this is the area most often hit with liquid spillage). Also check CPU_VIDSOUT, CPU_VIDALERT_L, CPU_VIDSCLK as well for impedance/activity.

[mon2]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

1) what is the voltage and current draw of the external power adapter?

2) what is the voltage to ground of ppbus_g3h ? Is it stable?

[cyber47]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

There is no DFU mode on T1 MAC's, only T2. What is the history of this machine? Any prior work on it (perhaps liquid damaged and already been through an ultrasonic)? Are the liquid damage indicators present or removed? Red or white if present?

Pay close attention to the pins around U7100, looking for any corrosion etc. Measure resistance of each coil for the CPU to ground, especially near the edges (as this is the area most often hit with liquid spillage). Also check CPU_VIDSOUT, CPU_VIDALERT_L, CPU_VIDSCLK as well for impedance/activity.

Thank you very much for your reply! I was on vacation over new year, so sorry for the late reply.

I don't know the history of the device, i bought it on ebay listed as not turning on. I don't see any signs of flux or other residue and the two liquid indicators i see are white.

U7100 has a little dust around, i cleaned it but otherwise it looks clean, i have a very low resistant to ground on CPU_VCCSASENSE_P, but i assume that is ok (around 1 Ohm resistance to ground, in diode-mode it shows zero)

I checked all the coils at the board again, the coils connected to PPVCCGT_CPU_PH1 are very low resistant, but also here i assume this is normal?

On CPU_VIDSOUT, CPU_VIDALERT_L and CPU_VIDSCLK my multimeter shows steady 1V if i connect the board to the charger.

Thanks again for your help!
Best regards

[cyber47]

Re: Macbook Pro A1706 (820-00923) no boot if display or Trackpad connected

1) what is the voltage and current draw of the external power adapter?

2) what is the voltage to ground of ppbus_g3h ? Is it stable?

Hello, thank you for your reply!
I am sorry for the late reply, i was on vacation over new year.

I have 20V and after initial changes around 0.8A to 0.9A Current draw, if i have nothing connected to the board (no fans, no keyboard ...). I made a short vid for you to show you my power consumption. You can find the video here: https://youtu.be/gQxMTpfbCIo (hope this is ok)

PPBUS_G3H is 13.03V to 13.04V and stable, i have measured PPBUS_G3H for about a minute and the value did not change.

Best regards and thank you for your reply!