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820-3437 no Trackpad and Keyboard

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Fizzl92

Member
Hello,
this 820-3437 was waterdamaged. Trackpad and Keyboard wont work and it did not see the battery. I followed the schematic and (it was cleaned before i got it) replaced the SMC because the ISL looks fine and the Pull ups on the dataline are good. Now it sees the battery, charges it and works without charger, but still no keyboard and Trackpad. I checked R5390 and R5391 ant they are fine. Without the cable connected to J4800 (must it be connected to troubleshoot this?) i checked that TPAD_SPI_IF_EN and TPAD_USB_IF_EN are not there. I am not sure if they have to be there... With an USB Keyboard it works. (As far as i know Keyboard is connected to USB internally and the external USB ports work...) I tried another Trackpad and the same. Now i am stuck.
Thanks for any help.
 
F

Fizzl92

Member
Connector and cable look fine as far as i can tell but i ordered new ones to be sure. Power Button works (as expected).
I measured the voltage on every Pin of J4800 with everything connected (unfortunately i have no good board to compare it to...):
Pin1: 3,4
Pin2: 0
Pin3: 0
Pin4: 0
Pin5: 0
Pin6: 0
Pin7: 0
Pin8: 0
Pin9: 0
Pin10: 3,3
Pin11: 3,3
Pin12: 2.8-3.3
Pin13: 2.8-3.3
Pin14: 5,13
Pin15: 0
Pin16: 3,3
Pin17: 3,3
Pin18: 3,4
Pin19: 3,4
Pin20: 3,4
 
F

Fizzl92

Member
No Title

I am still waiting for a new cable, but i tried a new housing with a new trackpad and keyboard. i attached a picture of all connectors on the trackpad and J4800. I think they all look ok. Should pin 9 of j4800 have voltage on it?
 

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D

dukefawks

Administrator
I see corrosion on the cable, I bet that is the issue. Pin 9 is a SPI data line so it would not have a set voltage on it.
 
F

Fizzl92

Member
New cable arrived today. I tried it with both my test housings (with 2 different trackpads and 2 keyboards - they both look fine but i have till now no board to verify function - ill do that as fast as possible) and the new cable still the same problem. Power button works tine but no other key or trackpad working. Any other idea?
 
F

Fizzl92

Member
i checked pin of 2,7,9,11,13 for continuity to the next resistor/part they lead to and everything beeps. I checked R4850-R4853 and they measure all under 40 ohms. Pin 12 and 13 on j4800 have pulsing voltage on them. Between 2.6 and 3.3V. TPAD_SPI_IF_EN is also pulsing between 2.8 and 3.3V. U4810 looks fine to me. PM_SLP_S4_L is strady at U4810.
 
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dukefawks

Administrator
So this is an SPI issue. The pulsing is normal if no SPI is detected. Check all pins for continuity to the connector on the trackpad.
 
F

Fizzl92

Member
i compared it to a working one and just Pin 12 and 13 are steady 3.3V on the good one. On the non working they are both fluctuation between 2.6 and 3.3V...
 
F

Fizzl92

Member
No Title

My bad, sorry. I did all measurements twice and i can not find any differences (picture attached) The only thing i can imagine now is bios... Because Keyboard and trackpad work both perfectly in Boot menu they have to be fine, right?
 

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    photo1408.png
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dukefawks

Administrator
No, in boot menu they work as a USB device and in OSX they use the SPI interface. SPI goes straight to the CPU, so this is either a dead CPU or corrosion under the connector.
 
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