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820-3462 - MacBook Pro Keyboard / Trackpad Not Functioning

M

mccafe

Member
Hello,

I have a MacBook Pro with non-functioning trackpad and keyboard. Tested new keyboard / trackpad and still not working. The keyboard (new and old) will only work if I hold the key a little bit.

I checked WS_KBD and all of them are fluctuating a lot between 0.5 to 3 volts. Never consistent. Connector looks clean and the U5701 area looks clean. Has the controller failed? Should I check elsewhere? PP3V3_S3_PSOC pin 49 and 22 of U5701 is 3.3 volts.

Please advise, thanks in advance.
 
2informaticos

2informaticos

Administrator
Staff member
Check R5701/02/04.
Be sure to have TPAD_VBUS_EN present.
Also check BUTTON_DISABLE.

Do you get correct powers at J5700?
 
M

mccafe

Member
Here are the readings.

R5701 - fluctuates 0.5 - 3 volts
R5702 - 0.00 - 0.02 cycles
R5704 - 3.3 volts

TPAD_VBUS_EN - 3.3 volts
BUTTON_DISABLE - 0 volts

Going to see what's the issue with R5701/02
 
2informaticos

2informaticos

Administrator
Staff member
If both resistors have good ohm value, change U5701.
There is USB line, complementary voltages; do nor expect 3V on both data lines.

Problems with other USB ports/devices will point to U2700 problem.
 
M

mccafe

Member
Okay, I will replace U5701. Must I get it from the same board number? Are there any other boards I can take it off of?

I noticed 820-3115 and 820-2936 have same
CY8C24794
337S2983
MLF
SYM_VER2

Does this mean they have similar firmware?
 
Last edited:
M

mccafe

Member
Okay, so I replaced U5701 (twice) and exact same result. WS_KBD fluctuating but it seems to be better? 1.5 - 3 volts Maybe a coincidence. I then replaced U2700 and still not working.

Z2_SCLK / Z2_CLKIN fluctuating 0.5 -1.5 volts.

Seems like there is only so many places to look, but I can't seem to find it.
 
M

mccafe

Member
The power rails for the keyboard is steady.

Here's something odd I found. When I disconnect the trackpad flex cable, the WS_KBDx signals are steady and the keyboard is very responsive. As soon as I reconnect the trackpad + flex cable, it jumps up and down. When I leave the trackpad flex connected and disconnect the actual trackpad from the flex cable, the WS_KBDx signals are steady. Tried new trackpad + new flex cable.

Looks like I'll need to order a trackpad connector and try that out.
 
2informaticos

2informaticos

Administrator
Staff member
Be aware of new flex from China; some people complained, needed to try 2-3 untill find good one.

Test continuity from MLB to trackpad board, when flex is connected.
You can also compare diode mode readings on the connector (TP connected), with a good board.
 
M

mccafe

Member
Okay, so I did more tests and then found that WS_KBDx signals + pin 2 / 9 of the TP connector (Z2_CLKIN & Z2_SCLK) were fluctuating regardless of whether or not TP is connected. I was convinced that maybe something was in the TP connector (because why all of a sudden is it acting like this after reconnecting flex cable several times?) so I ended up removing it.

Now that it has been removed, it's still fluctuating with no keyboard connected, no TP connected (obviously) and now I have a board with no TP connector! I am having some difficult sourcing out the part online. Now everything is pointing back to a controller issue which I replaced 3-4 times already.
 
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