Problem with Pavilion dv8 top slider bar (treble/bass control)

[brian220x]

I am wondering if there are any laws that govern the replacement policy like the lemon law. After 3 repair attempts for the same problem would usually require the manufacturer to replace it with a new unit of the same or equal value. I don't know if this applies to laptops but it does apply to all kinds of other consumer products so I don't see why not.

[joshberke]

It might but meanwhile, my laptop's sensor bar is out of whack, I've replaced one hard drive, and the laptop over heated one day and used to make a grinding sound when the fan runs...(Had to pull the case apart to get it to stop....so it must have warped when it overheated). I can't go without a computer for 2-3 weeks while I ship this one back. So I'm stuck with what I got lemon law or not until, I buy a new laptop...just need to make sure I buy it before the warranty expires. 

[Tas]

I have had the exact same problem.  Hp fixed it once, replacing what they called Switchboard PCA.  (Printed Circuit Assembly).  It happened the first time after 10months of purchase.  It is now happening again almost 3months later.  I called and they will replace again.  (free still under warrenty)  However if it happens again i will be out of warrenty.  I will be contacting them to replace this unit that cost 2k dollars. 

I have 6 HP computers and never had a prob. with any of them except this one.  I will continue to purchase Hp if this prob is fixed in a timely manner or my money returned to me so that i may purchase something more reliable.

[brian220x]

Here is some good info on capacitive touch sensing. This explains the art of correctly setting up the firmware for a device like this. Its a shame that HP isnt able to release a simple firmware update for the touch panel PCB controller. I am almost sure that the touch panel controller is run by an onboard chip located on the motherboard that is independent of the operating system so this rules out the option of revising the firmware. If anyone knows if there is some way to access the firmware for this device please let me know.

http://www.eetimes.com/design/analog-design/4009622/The-art-of-capacitive-touch-sensing

 I should be able to get this work with a few mods but a firmware revision would be much easier.

[puddinck]

I just wanted to add my voice to the forum in case any one at HP is actually paying attention.  I am also EXTREMELY frustated with the malfunctioning quick launch buttons.  I have gone through many of the steps already mentioned (unistall/reinstall quick launch driver, BIOS update, system recovery) several times during at least 8 phonecalls to tech support with no luck. Why do they even write service ticket notes if the next tech doesn't read them?   I have not been brave enough to uninstall any programs/drivers on my own or open up the laptop to disconnect the buttons.  I am now in the process of sending my computer in for repair but I'm not hopeful after reading the posts here.  My warranty is up next week but HP will extend the coverage on this problem an additional 3 months if I send it in.  I'm hopeful that if I send it in enough times that they will either buy it back or replace it with an updated model.  I can't believe that HP hasn't addressed this issue and that every tech I speak to acts like this is an unusual problem.

For those of you having problems with the fingerprint reader I have discovered that patience is the key.  I used to swipe my finger as soon as I saw the icon come up and sometimes it would cause my login screen to get caught in what I called a refresh loop.  It would say "fingerprint reader not detected" and the screen would seen to hiccup or flash.  If I went to the other option of typing in my password the screen would refresh before I could enter my whole password.  I wasn't clever enough to type it in backwards as one other poster mentioned instead I would use the right arrow key and race to type in a character or two before it reset to the left.  It would usually take me three or four cycles and then I'd keep my fingers crossed that I'd typed it correctly.  I now WAIT a few seconds after seeing the icon and make sure that the text is actually promting me to swipe.  The problem only seems to occur when a finger is swiped before the reader is ready.  Logging on has been trouble free for several months now. 

[brian220x]

Hi Guys,

I have been doing more research and I need everyone to try something to see what the affect is. The cause could be from a few possible issues. At the heart of the issue is the touch controller design or firmware. Things that can affect the controller and its programing can range from an issue with the charger to EMI and static charge and interference. Not only does it need good grounding but it also needs a capacitive ground that is setup right. The charger and PCB/touch panel can all contribute to this issue. I am working to see what defect I can negate with some simple revisions.

The reason that sometimes the buttons work fine and sometimes they don't is likely related to how the touch controller calculates the baseline average capacitance value in order to sense when the button is touched. When there is a build up of static or EMI interference the moving average for touched and untouched is altered and the programming likely does not have guard bands that prevent this from occuring. If it is using guard bands the average could land outside of the band with no way to recover it. This may be why resetting the computer by unplugging it and removing the battery is sometimes a temporary solution.

I need everyone to try holding a finger or two on the malfunctioning buttons for a few minutes only when they begin to self activate. The idea is that this may help to raise the moving average to a higher level basically decreasing the sensitivity of the touch button and will hopefully prevent false triggers. This will not permanently change anything and it is only temporarily and it may not work at all depending on how the controller works. Everyone's results will help me determine how the controller is programmed and how I will design a possible solution.

I just had the wifi pop on and off so I held my finger lightly on the mute and wifi button for a few minutes while the system is on and booted up. So far it has not gone crazy yet. This could indicate an average sensing issue.

Normally this kind of problem would cause the buttons to loose sensitivity but if the controller calculates averages for both the pressed average value and the depressed average value this could result in hyper sensitive buttons. There are a few programming scenarios that can also have the same result.

Please let me know how your system responds when trying the above test.

Thanks,

Brian

[brian220x]

One more thing, when the buttons go crazy try unplugging the power cord and see if there is any change.

Thanks,

Brian

[brian220x]

When looking at the layout of the components there are a few areas of concern. The mini sub woofer is directly under the harness connector for the cap touch board and the LCD power and signal wires run directly under it as well. The blueray/dvd drive is also partially under the right side of the touch board and the the two speakers are on ether side.

There is not much choice for the design engineer for placement of these parts but proper shielding must be used to avoid interference. I am going to add to the existing shielding as well as improve the protection around the harness plug. There is a major problem with the area on the touch board where the harness plug is since I can push on that area and it will turn on or off the sound and wifi even though there isnt a touch button where I am pressing. Pressing just above the F9 key will be one way to test the revised shielding.

What type of optical drive does everyone have? Is it a DVD drive or a Blueray/DVD combo drive? I am wondering if one type of drive emits more interference.

[puddinck]

Brian,

I tried what you suggested and held my fingers down on the quck launch buttons during an episode.  As long as my fingers were actually making contact the treble/bass slider bar would stay off my screen but as soon as I lifted my finger it would reappear and behave as before.

I almost never use my laptop while hooked up to the power supply so I can't try your other suggestion.

I'm planning to send my computer in for service today but as I'm not counting on an actual fix I will be looking forward to any solutions you come up with.

[puddinck]

I have a blueray/DVD combo drive.