820-00045 keyboard and trackpad not working

ytesfay80

New member
I have this 12 inch 2015 Macbook that had liquid spilled on it and the keyboard flex cable was damaged. The trackpad had lots of corrosion on it but not much on the logic board even though I haven't been able to completely remove the logic board since I'm missing the Y00 driver bit.
I replaced the keyboard cable, trackpad cable and trackpad but still the keyboard and trackpad are not working. The only thing that changed is that now the power button is working to turn it on and off.

I took a closer look at the trackpad connector on the logic board(J4801) and I noticed there was burned powder next to the connector and after putting some alcohol and cleaning the area I noticed that F4800 was gone and the pads were empty so I assume F4800 was burned off. L4800 and the connector look fine visually.
I am getting 5v on Pin 24.

I don't have a replacement fuse for it but I ran a jumper so the pads were connected but still the issue remains.

Do you know what else could be causing this?

Also, I can't find a fuse with the specs of F4800. Does anyone know where I could get this part or can someone in the US sell me a donor board for this model?
 
Last edited:

G.Beard

New member
Keyboard has some electronics on on the back of it. Change the keyboard. Done a few of these and most of them neded a new keyboard.
Can't you ust jumper the fuse with some fuse wire?
 
Last edited:

ytesfay80

New member
There was nothing left of the fuse except for pads which I jumpered together. I disconnected the keyboard cable from the trackpad but I'm still not able to move the trackpad. I can tell the trackpad is somewhat working because when the machine is on I can feel the trackpad is clicking which it doesn't when the machine is off.
Will the trackpad not work without a working keyboard plugged in like the 2015 rMBP's?

Can you replace these keyboards without replacing the entire topcase because all the prices were about $300+ for the topcase?
 

G.Beard

New member
I can't remember what the electronics are on the back of the KB. Duke knows.
You'll notice when you take the old KB off that you can break them into bits. If you bend them they just snap.
 
Last edited:

ytesfay80

New member
So the keyboard is like the airs where its riveted to the case and you just need to rip it off?

I don't want to order a keyboard only to find out that the trackpad or keyboard still isn't working. I'm curious why my trackpad isn't working even with the keyboard not plugged in.
Also, is there a better alternative for the fuse that was missing because I thought that just using solder to jump the pads together will cause issues down the line?

I also read another post from a few months ago and duke said its a pain to fit the new keyboard. Have you had that issue as well?
 
Last edited:

G.Beard

New member
No the KB is screwed on. It's not that bad to fit the KB really. Trackpads are like £15 on eBay.
 

ytesfay80

New member
Okay.
I already put in a new trackpad & cable from ebay which is why I don't understand how the trackpad is still not working for me.
 

G.Beard

New member
Hmm. I don't know about that.
I do know I bought a cable from eBay and bent it once which fucked it up.

You might want to investigate the board further first.
 

dukefawks

Administrator
Trackpad should work with a disconnected keyboard. Look up J4801 in the diagram and check all voltages. Check connector for corrosion.
If you have a adapter from USBC to USB see if the trackpad works in the boot menu.
 

ytesfay80

New member
Okay I believe I read the schematic right on J4801 that the side where Pins 1/41 are on can be measured from the connector on the trackpad board.
If so all the pins gave me correct readings except for Pins 7,9,35,37,39,41 which all gave me 0v.

I measured from left to right and the first two pins on the left gave me 8v each and the third pin(I assume is Pin 5) gave me 0v.
 
Last edited:

dukefawks

Administrator
I have no idea what you measured. Use the board view and compare the pin numbers.
You can say left to right but how do I know which way you are looking at the machine......
 

ytesfay80

New member
The reason I'm saying that is because I have to measure on connector that is on the trackpad since I can't measure the logic board connector and have the cable plugged in at the same time.

I got these measurements from the connector that is on the trackpad. (J4801)
Pins 1/3 - 8v
Pin 5 - 0v
Pins 7/9/35/37/39/41 - 0v
Pin 11 - 3.26v
Pin 13 - 5v
Pin 15 - 3.3v
Pin 21 - 3.3v
Pin 23 - 5v
I'm not sure why pins 7,35,37,39 & 41 show 0v because when I measure on the other side with the cable disconnected from the trackpad
Pins 10,36,38,&40 all give me the proper voltages.
 
Last edited:

dukefawks

Administrator
And how would I know what is pin 1 on the trackpad connector and what that pin even is. This is all useless information.....
Measure on the board without trackpad connected. Or don't be lazy and take a separate trackpad and connect that.
 

ytesfay80

New member
Okay I separated the trackpad and took these measurements with both the trackpad flex and keyboard flex plugged in.

J4801
Pin 40/38/36 - 7.64v
Pins 34/32/30/28 - 0v
Pin 26 - 3.27v
Pin 24 - 5v
Pin 22 - 3.3v
Pins 20/18 - 0v
Pin 16 - 3.3v
Pin 14 - 4.98v
Pin 12 - 0v
Pin 10 - 3.28v
Pin 8 - Pulses from around 2v down to as low as 1.8v
Pin 6 - goes from 0.18v to 0.27v
Pin 4 - 0v
Pin 2 - 0v
 
Last edited:

ytesfay80

New member
Come on man, missing half the pins.......
I don't understand. I gave the measurements for even pins from 2-40 and I thought the odd numbers from 1-41 where the previous measurements I gave from the connector that is on the trackpad.
Where are the other half of the pins so I can measure them and do I need to keep the trackpad flex cable plugged in?
 

ytesfay80

New member
I assumed pins 1 and 3 were on the connector that was on the trackpad but from reading the schematic it says its on the bottom side of the logic board which means I would need to disconnect the battery and measure under the board.
 
Last edited:

ytesfay80

New member
Okay could you just help me to get it back working as it was before so I can send it back to the customer working as it was before.
Now when I plug in the charger the machine doesn't turn on. Before the customer would keep it in sleep mode and I have a usb keyboard that would wake it up from sleep but its not turning on anymore.
I disconnected the keyboard and trackpad cables and plugged in the charger to see if the screen would turn on but it doesn't.
I get 3.3v on PP3V3_S0SW_LCD of j8300.
I also still got 8.2v on F4800 as well as 3.3v on SMC_ONOFF_L on J4801.

I tried shorting Pin 22(SMC_ONOFF_L) of J4801 to ground but that didn't work either.
 
Last edited:
Top