820-01958 no image/no display

Victor Holley

New member
Liquid damaged 820-01958.
Initial presentation on usb-c ammeter:
First test: 20v and 0.03A Second test: 5v off and on alternating.

No boardview. Tried to map the water to 820-01521 boardview. Water was at Q7660 and Q7680. Water discolored crystal Y1900. Water was at some tiny resistor near the crystal that I could not determine identity using the 820-01521 boardview.

Ultrasonic cleaned.

Board seems to boot, with no display. 20v and 1-2A current. Charges the battery. Put board in a known good housing for 820-01521--same, no display.
Usb-c makes sound on connect/disconnect.

Tried to check external display as follows: Plug in usb-c HDMI dongle, connect monitor. No image on monitor. Confirmed known good 820-01521 produces external display.

Checked board again. Now found blown filter--may have missed on first look. Filter is probably L6701, L6702, L6703 by mapping to 820-01521. Likely trackpad.

Tested board again making sure trackpad not plugged in.

No display.

Diode mode at J8500 compared to logi.wiki for 820-01521. No short or open found.

And here I am!

What is the next step? Keep in mind I am not very experienced with Macbooks in general and may be missing some basics.
 

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

What is the actual behaviour on the USB-C ports?
One steady 20V and other 5V cycling?

To see if board really boots, check for USB activity.
 

Victor Holley

New member
After ultrasonic cleaning the usb-c ammeter on both ports is the same, normal.
20v 1-2A and battery charges.


I am not sure of the best way to check usb activity,
I plug in a usb-c android phone and it does charge.

I think usb activity is good. No image/display. I have confirmed that the display is good by plugging my known good 820-01521 board into this housing and screen works.
 

2informaticos

Administrator
Staff member
Power presence on USB-C port is not the same with activity.
Plug an USB pendrive installer with Link LED; if flashes, there is USB activity 100%.
 

Victor Holley

New member
I can do that, but I will have to order something to plug in that will show a light. Can we move forward for today? I did hear a chime when plugging into usb port earlier.

Can we discuss "If you confirm usb activity, then with diode mode on screen connector nothing short/open THEN....???"


and

If you have no usb activity, but laptop is charging with 20v 1-2amp on usbc port, THEN.....???

I would love to understand a framework of how to explore both of these questions.
 

Victor Holley

New member
I have tried a usb-c LED mouse. The LED does light up.
I have tried a usb-c spinning hard drive, it does spin.


When I use a usbc HDMI dongle--no image on external display.

I do NOT hear a chime when I boot the macbook.

I DO hear a "ding dong" when I connect or disconnect usb c


What would you do next?
 

Victor Holley

New member
Does this device have PRAM?

I tried holding down cmd-option-p-r while connecting usb-c
Also tried holding down cmd-option-p-r while connecting usb and pressing power button
 

2informaticos

Administrator
Staff member
"Plug an USB pendrive installer with Link LED; if flashes, there is USB activity 100%."
Did that?
An USB HDD adapter should have a Link LED.
 

Victor Holley

New member
I searched Amazon for "usb c flash drive led" and did not find any results. Do you have a link? I am in the US.

I ordered the usbc mouse with LED and it does light up. I do not know if that is a data connection or not for the lights.
I have a usbc HDD but it does not have a light. When I plug in this HDD I can hear it spinning. I do not know if that is proof of data connection or not.
 

2informaticos

Administrator
Staff member
Any USB pendrive with LED, should flash when connect it.

I use such pendrive with preinstalled macOS.
I'm sure you can find it in US too.
 

Victor Holley

New member
Usb-c external HDD confirmed to light up and blinks very little and then steady.
Confirmed on a working MBP the activity light should blink more and then stay steady.
 

2informaticos

Administrator
Staff member
These high-density board are very sensitive to liquid spill.
Could be just a simple corroded resistor/cap, or accumulated crap under some BGA chip.
But also CPU may have been damaged.
Leakage from backlight, or PPBUS_G3H to data lines, can be letal.
 
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