820-2327 trackpad cant click.

[keeney123]

Re: 820-2327 trackpad cant click.

One other thing. Make sure Q5701 is not shorted out Drain to Source as that would also keep the track pad disable low.

[Larry Offley]

Re: 820-2327 trackpad cant click.

One other thing. Make sure Q5701 is not shorted out Drain to Source as that would also keep the track pad disable low.

Ok with the machine off there should be no connection from drain to source?

I will check

[Larry Offley]

Re: 820-2327 trackpad cant click.

One other thing. Make sure Q5701 is not shorted out Drain to Source as that would also keep the track pad disable low.

Measuring from drain to source in diode mode i get .6v

[keeney123]

Re: 820-2327 trackpad cant click.

I was wonder what the ohm measurement was. 0.6 volts is that in the diode mode? They have a protection diode between S and D. You might be forward biasing that diode. Try to set meter to 200 ohm range or lowest range on the meter. Measure S to D with the leads one way and then the other way. Hopefully you are using a digital meter? If you get a low reading either way like 20 ohms or less I would think that the FET maybe bad. If this is the case you will have to desolder at least one leg, S or D to comfirm it is the FET and not the micro controller.

[Larry Offley]

Re: 820-2327 trackpad cant click.

I was wonder what the ohm measurement was. 0.6 volts is that in the diode mode? They have a protection diode between S and D. You might be forward biasing that diode. Try to set meter to 200 ohm range or lowest range on the meter. Measure S to D with the leads one way and then the other way. Hopefully you are using a digital meter? If you get a low reading either way like 20 ohms or less I would think that the FET maybe bad. If this is the case you will have to desolder at least one leg, S or D to confirm it is the FET and not the micro controller.

at 200ohm range it is open both ways at 20M ohm range i get 10M and 6M the other so no short.

I did some more testing and did find the track pad does click but latches down so when you release the button the computer still thinks it is depressed. I starting to think the maybe something internal to the U5701 usb controller. Or if something in the SMC is registering the depress but not the release.

ANy Ideas?

Thank You for your help.

[keeney123]

Re: 820-2327 trackpad cant click.

Just had a quick look, but it would seem on the UBS it writes out but does not read. Maybe a bad connection going out the track pad on the UBS

[keeney123]

Re: 820-2327 trackpad cant click.

You could also have a corrupt UBS driver for the track pad. Did you do the diagnostic test by holding down on the D button on start up? Also, try testing out the keyboard all the characters shift and control to see if they respond as they share the same micro controller. If all the keyboard characters test out then I would not suspect an IC. If there are also some characters that fail then yes it could be an IC. The diagnostic test may also have a keyboard test built into it.

[keeney123]

Re: 820-2327 trackpad cant click.

It would also be good to know did this system work OK when you have owned it or did you receive this in this condition?

[Larry Offley]

Re: 820-2327 trackpad cant click.

You could also have a corrupt UBS driver for the track pad. Did you do the diagnostic test by holding down on the D button on start up? Also, try testing out the keyboard all the characters shift and control to see if they respond as they share the same micro controller. If all the keyboard characters test out then I would not suspect an IC. If there are also some characters that fail then yes it could be an IC. The diagnostic test may also have a keyboard test built into it.

The Apple Diag passed no problem.

I received it like this and When I opened it I could tell there was liquid damage.

I am going to look through my dead boards pile to see if I have another one. Might be better off using parts from this to fix a different one.

[Larry Offley]

Re: 820-2327 trackpad cant click.

I know it is not a driver as the problem exists before the os loads.

[keeney123]

Re: 820-2327 trackpad cant click.

I know it is not a driver as the problem exists before the os loads.

If the driver is corrupt then it would not matter when it loaded. The driver itself would be bad. That would mean that the software would have a fault to it. So was there a keyboard test in the diagnostic test? They say there is different sections in the diagnostic test. One of those test is the peripherals like the track pad and keyboard. They need to be attached in order to test them. Best to get all the information of what is wrong then to eliminate things one at a time, working from what is easiest to check to the more complex. What is the operating system on your computer?

[Larry Offley]

Re: 820-2327 trackpad cant click.

If the driver is corrupt then it would not matter when it loaded. The driver itself would be bad. That would mean that the software would have a fault to it. So was there a keyboard test in the diagnostic test? They say there is different sections in the diagnostic test. One of those test is the peripherals like the track pad and keyboard. They need to be attached in order to test them. Best to get all the information of what is wrong then to eliminate things one at a time, working from what is easiest to check to the more complex. What is the operating system on your computer?

There is not a test like that in the apple diag. ON a mac if you hold the option key down when you turn it on you get a graphic boot menu normally you can use the track pad to click on what item you want to boot from. So at that point you are using the builtin firmware. It doesn't work there or if i boot off a known working os install off one of my external hdd.

Sure the firmware could be bad. that would be in the SMC and that would be a nightmare to change.

Thank You for all your help but I think I am going to give up on this one.

[keeney123]

Re: 820-2327 trackpad cant click.

So this is what I got off the Apple site. Also, if you have another known good track pad you can just plug it in, if that one works then you know it is in the old track pad. If it does not then it has something to do with the computer.

Using Apple Hardware Test

1. Shut down your computer. Then, press the power button to turn it back on.
2. Press and hold the D key before the gray startup screen appears.
3. It takes a minute or so for AHT to start up and inspect your hardware configuration. While this is taking place, an icon appears on the screen:
   
4. When the process is complete, select your language and click the right arrow. If you aren't using a mouse, you can use the up and down arrows to select a language and then press the Return key.
5. The AHT console appears. You can choose which sort of test or tests to perform:
   • To perform all of the basic tests, click the Test button or press the "T" key or the Return key.
   • To perform a more thorough diagnostic test, select the "Perform extended testing" checkbox under the Test button before you click the Test button.
   
   Note: Your test results will appear in the window in the bottom-right of the console.
   
6. To exit AHT, click Restart or Shut Down at the bottom of the window.

Some Macintosh computers that shipped with OS X Lion and later support the use of Apple Hardware Test over the Internet. These computers will start up to an Internet-based version of AHT if the hard drive does not contain AHT. An Internet-enabled connection via Ethernet or Wi-Fi is required to use this feature. Internet-based AHT functions the same as AHT on the hard drive or flash storage outlined above.
Using Apple Hardware Test on computers with OS X v10.7 and earlier
AHT is located on the Applications Install Disc 2 and should be included with your computer or the MacBook Air Software Reinstall Drive on a MacBook Air (Late 2010). To start AHT on these computers make sure the Applications Install Disc 2 is inserted into the built-in optical drive, external Apple Superdrive, or for the MacBook Air (Late 2010) be sure the MacBook Air Software Reinstall Drive is inserted into a USB port. Then, follow steps 1-6 outlined in the previous section of this article.
What to do if you get an error in AHT

1. Confirm that the power adapter is connected if you're using a Mac notebook.
2. Confirm that all external devices are disconnected from your computer.
3. Record any error code given so that you can give the information to a Mac Genius, Apple Authorized Service Provider, or Apple Technical Support Specialist.

[Larry Offley]

Re: 820-2327 trackpad cant click.

Like I said I already tried a known working trackpad and I get no error from the AHT software. I am 90% sure it is a component on the board. I seems at this point to be that the button latches on the down and never releases on up. so that after the first press the computer believes the hardware is depressed until the machine has been reset.

[keeney123]

Re: 820-2327 trackpad cant click.

I did not catch that you already tried a good track pad. So did the good track pad work? If it did work, limiting it to the track pad will limit the possibilities. I would then say if there is a connector and cable that goes to the track pad and you have check that out it is most likely that micro controller. If you have a o-scope you can actually compare what happens with the good track pad when you click that as apposed to the bad one. On the track pad UBS data I would think the computer would register the click and then send a return signal to the Micro Controller to see if the button is being held down. The computer would be looking for some information to determine that. If the Micro Controller does not receive the signal coming from the computer then it will not react to see if the button is held down so when you release the button nothing happens. If the good track pad did not work the problem is in the computer.

[Larry Offley]

Re: 820-2327 trackpad cant click.

I did not catch that you already tried a good track pad. So did the good track pad work? If it did work, limiting it to the track pad will limit the possibilities. I would then say if there is a connector and cable that goes to the track pad and you have check that out it is most likely that micro controller. If you have a o-scope you can actually compare what happens with the good track pad when you click that as apposed to the bad one. On the track pad UBS data I would think the computer would register the click and then send a return signal to the Micro Controller to see if the button is being held down. The computer would be looking for some information to determine that. If the Micro Controller does not receive the signal coming from the computer then it will not react to see if the button is held down so when you release the button nothing happens. If the good track pad did not work the problem is in the computer.

A known working trackpad does the same thing. It is probably that usb cntrlr that the trackpad connects too. If I can find a replacement on a dead board I might try changing it with my hot air station its is already broken so I can make it worse as far as i am concerned

[keeney123]

Re: 820-2327 trackpad cant click.

To me it sounds like a software problem. Have you tried going this?

Troubleshooting Erratic Mouse & Trackpad Behavior on a Mac by Ditching Input plist Files

It's unlikely something will go terribly wrong with this process but it's always a good idea to backup a Mac before deleting any important files and preference files anyway. Do that with Time Machine or your back up method of choice, then you're ready to go.

1. From the OS X Finder, hit Command+Shift+G to bring up “Go To Folder”
2. Enter the following path: ~/Library/Preferences/ and choose Go
3. Locate the following files manually, or use the Search box in the upper right corner and narrow down for ‘driver' to find them – remove the ones that are relevant to your issue:com.apple.driver.AppleBluetoothMultitouch.trackpad.plist - Magic Trackpad
   com.apple.driver.AppleBluetoothMultitouch.mouse.plist - Magic Mouse
   com.apple.driver.AppleHIDMouse.plist - wired USB mouse
   com.apple.AppleMultitouchTrackpad.plist
   com.apple.preference.trackpad.plist
4. Drag the appropriate files* to the desktop to make a backup of them, or just delete the files* if you're comfortable with that
5. Leave the user Preferences folder and reboot the Mac

*Note: you can get more specific if you want, like only deleting the AppleHIDMouse.plist file if you are only using a USB mouse, or only removing BlueToothMultitouch.mouse if you only use a Magic Mouse, or you can ditch all of the plist files if you're using all of them.

With a reboot the Mac will rebuild the preference files for the input devices that are in use, and, hopefully at least, the erroneous tracking or clicking behavior will be resolved.
Remember, by ditching the preference files you'l lose customizations made to things like tracking speed, alt-click, gestures, and clicking behavior, so you'll want to go back to the appropriate System Preference panel and reconfigure any specifics you had beforehand.

[Larry Offley]

Re: 820-2327 trackpad cant click.

As I said before It is like this before the os boots and even booting off a known working os. One of the things that make determining SW vs HW on the mac is the fact it is so easy to boot a diffrent clean os.

[keeney123]

Re: 820-2327 trackpad cant click.

I do not know a great deal about software and on a Mac even less. I know on a PC they have a device manager and if something is wrong with the driver it will show up. I am not sure if the permissions on the Apple are computer dependent or not, so then putting another OS on the same computer would not matter. The other thing I have read on the internet is a swollen battery can cause problems with the trackpad as it pushes up on it. At this point we know it is the computer that is the problem. The only hardware problem I can think of would be the connector on the main computer that goes to the trackpad USB some junk could of gotten under it, possible it might of taken out just that one connection. More than likely if it was a hardware problem on the main computer it would show up else where not limited to one type of operation.