Touchscreen not working with generic USB Charger!?

[yungwunn911]

Sorry, didn't get home til late last night.

I stripped down the cable that doesn't work right and as I suspected, it's unshielded. Also, the data cables are untwisted, so there's no protection from EM interference. Interference along the cable is picking up is probably reaching the touch screen causing it to be either wonky or non-responsive altogether.

For those that are having this issue with a cable, check to see if it's grounded. If you don't want to cut it open, compare it to the cable included with the EVO. The unshielded cable will be noticeably more flexible when you bend it; it should be pretty obvious to tell the difference. If you can't tell the difference and are willing to sacrifice the cable buy cutting it, that will leave no doubt. I only have the one cable that didn't work, so I'm curious if any shielded cables are doing it too. That way we can identify that shielded cables are required and save some people headaches.

There's also the issue of pins 4 and 5, but that's much more difficult to test so I'd like more feedback on the cable shielding first.

Makes sense though. The copper and aluminum that goes into a cable shielding is the most expensive part of the cable. Stands to reason that a budget, generic cable would leave that out to keep cost down.

will try my bb charger on my work computer to see what happens...Thanks for the info!!

 

[mikegoldnj]

No problems with the usb from my blackberry charging the EVO off the Mac USB.

 

[Darth Mo]

No problems with the usb from my blackberry charging the EVO off the Mac USB.

I don't think anyone should have a problem with a branded or OEM cable included with another device.

It's the cables off eBay or a generic house brand from a store that are the ones in question.

 

[yungwunn911]

No problems with the usb from my blackberry charging the EVO off the Mac USB.

I second this sans MAC. Running off of PC desktop.

However, plugging into my keyboard's USB gave me a "USB POWER EXCEEDED" error, had to plug diretly to the tower.

 

[SurplusGadgets]

The thread is awesome. I thought I was going crazy. So here is info based on refined testing directed by your comments above.

But first, my failure mode seems slightly different. The screen continues to operate normally. It is solely the four buttons on the bottom that fail. Sometimes all four. Sometimes only the home button. By fail, I mean hitting it does not cause an action. In all cases of failure though, hitting the home button causes the screen to flash but no action to occur. As a result, not sure if my results will be applicable to your problem -- is it the same problem?

After testing, it appears to be solely the connector, and not the amperage of the charger or shielding / quality of the cable. The HTC supplied charger is 1 Amp and its cable rated high speed with shielding. Higher and lower amp chargers as well as lesser quality cables (even simply a two wire charging-only cable) do not induce the problem for me.

Specifically, I have 8 micro- to mini-USB adapters. 4 of these 8 cause the buttons to fail consistently. The working 4 will allow any combination of cable and charger to be used behind it without exhibiting the failure. In fact, just plugging the adapters in, without any cable or charger attached to the other end of the 1" long unit, will replicate the failure pattern. That is, the same four cause the phone to fail just by the adapter being plugged into the phone whereas the other 4 allow the phone to operate whether a cable or charger is connected or not. So an unshielded cable does not seem to be the issue. It is in the connector somehow. Also, simply plugging in the bad adapter causes the screen to flash the same way it flashes when hitting the home button (a good adapter being plugged in and hitting buttons normally never causes the screen to flash and the home button causes an immediate and quick expected response).

Can provide details of testing but I have many different amperage wall charges, auto chargers, and cables. Most are mini-USB with only the HTC supplied cable being micro-USB in addition to my adapters. But I have many USB-outlet chargers and current sources that I could use on the HTC cable. I checked every combination of cabling, charger, and adapter and found nothing consistent other than the same four adapters inducing the problem. Even a 500 mA charger did not induce the button problem; nor a 2-wire, unshielded "power only" cable.

Note that USB standard only requires a USB HUB to provide 1 A maximum power (for up to 4 connectors). I think the maximum draw for any one device is supposed to be .5 A (or 500 mA) if I recall correctly. Most laptops and often desktops only have one hub powering the multiple external ports. A hub can have up to 8 connectors but I think the standard requires 1 Amp per 4 connectors. Most USB car charge docs I have found are 1 Amp minimum.

I recall the "car jack" mode where the EVO wants to keep on the "Navigation" app causing a similar flashing. (Have you seen how in car jack mode hitting the home button flashes the home screen before going to the Navigation app home panel. Similar to the bad behavior of the home button causing a flashing here it seems.) So one more test.

Went in and changed the default / fixed action for plugging in a USB cable to be "charge only". Tried the different combos of cables, chargers and adapters. Consistent failure mode only pointing to specific adapters.

So clearly there is some sensitivity in the USB port on the EVO 4G to the type of connector used; even if charge-only mode for the USB is on. The phone does not appear to be too amperage sensitive (at least for inducing this button problem). Look forward to your further refinements of these test results. Especially if you see similar model products inducing or not inducing the problem; or other adapters (without cables or chargers attached) inducing the problem.

 

[Jonsdog7]

So I noticed this problem also. I didn't realise why it was happening I thought something was wrong with my phone but basicly Touch screen seems unresponsive or when it does respond it clicks in the wrong places. I have major problems "sliding to unlock" if I get that far then if I go to check messages it will click home or search ect. Or sometimes it will expand to show all the screens.

I just recently put 2 and 2 together and decided to research this a bit and stumbled upon this discussion so I hope to add to it a bit.

Everything works fine when I use the AC Wall Adapter to usb supplied with my HTC EVO phone. It also works fine if its pluged into my computer.

The problem shows up when I plug it into the AC Battery docking station/ USB adapter I bought off amazon (company websites htcexpress.com) which I assumed was from HTC because it says "HTC" on the red 1800mAh battery but come to realise its not like the "htc" on the factory battery so I am now doughtfull but still was decent considering the price.

The only differences between the specs printed on the adapters:
htc evo wall adapter: 5v 1A (feels well insulated and heavy compared to size)
Non-Factory(HTCexpress.com) adapter:5v 800mA (feels light and cheap)

Some factors I believe that can cause it are that the components are leaking some electricity onto other pins or poor quality electronics. When you convert AC to DC it tends to not be as "clean" as if you power it from a battery (thats why cheap led christmas lights always have that annoying "flicker" to them compared to professional led lighting) and depending on the quality electronics this can possibly be worse. Then this might happen to cause interference then with the phones touch screen?

The only other thing I can think of is if the plug is poorly grounding from the AC adapter to the usb plug. Possibly effecting the phones gound?

I'm not an expert I'm just putting some of my ideas out there and I'd love feedback or answers.

 

[baseballfanz]

Great infos. I jsut got a Samsung Captivate and used my son's old micro usb car charger (cheap chinese made). Screen frozed and didn't work at all.
Guess it's to AT&T to get their $30 car charger.

 

[AdamC]

I can say that the wall charger from my BB 9630 charges the phone fine with total responsiveness, however when I use my car charger it makes the screen much less responsive unless I have my other hand on the phone. You can see this being a problem, lol

 

[martin_coxy]

This is definitely a grounding problem (at least in my case). With my new generic usb charger My Galaxy S2 screen doesn't respond at all when charging and my ipad is erratic. Both devices are fine with the same cables but a different usb charger.

Therefore, it isn't the devices or the cables but the OEM charger. If I unplug everything they work fine and if I touch the iPad case with my free hand to ground it, it's also fine. With the S2, I can only make it work if I loosen the USB at the charger end just enough so that I can touch the metal connector, then it's also fine.

I'm guessing that 500mA is low for the devices so they are susceptible to the poor grounding. I previously had another charger that was rated as 'max 1A' and it worked fine.

So.. the answer is, don't buy a cheap OEM charger on eBay or be prepared to ground the device, or unplug it when you want to use it..

By the way, my "max 1A" charger had two USB slots and when I plugged in two iPads, it burned out, (hence the new one), so I'm pretty sure the iPad draws more than 500mA. This would also explain why it's not so happy with this charger asking it to limp along on 500mA.

 

[PlaidRadish]

MORE INFO TO ADD TO THIS TOPIC:

I have a cheap micro USB cable that I use on my Android devices (Samsung Captivate and Samsung Infuse), and have had the touchscreen errors as listed here in this thread. I saw one of the posts here about the AC/DC conversion concerns when using a poorly shielded cable, and it got me to wondering if my adapter on my computer could also play a role in this error. Guess what? It did.

I was plugging my Samsung mobile phones into a MacBook Pro using the cheap USB micro cable when I noticed the malfunctions on the touchscreen: some items did not respond, some responded with the wrong function. Then, I unplugged the USB cable and everything worked fine.

THEN, for kicks, I plugged the USB cable back into the MacBook (same touchscreen problems) and then UNPLUGGED MY POWER ADAPTER FROM MY COMPUTER. The Samsung Android devices began working correctly once again!

Assessment: cheap USB cables do not shield AC current well, and cause malfunctioning...unplugging the USB cable will resolve, but unplugging the power from your computer may ALSO resolve. The upside is, if you really need to charge your phone, your laptop's battery can do it without making the touchscreen malfunction.

hope this helps,
jeff

 

[Adam S2]

So I have just stumbled upon this problem myself, unfortunately.

Now here is something that will blow all these theories out of the water..... I AM USING OEM CHARGER!!

Weird thing is charges fine on my ffs OEM charger. Other weird thing is even with Ph off charge starts opening apps and doing crazy things by itself. I wake up and recorder is on, very random.

Not holding my breath for a fix but def not buying HTC again. Such a lack of user support and endless glitches bugs and probs with phone.

 

[kainaw]

I know this is an old forum, but I want to help explain the problem. First, go into settings and then developer settings (depending on your version, the name has something to do with developing or testing). Newer versions of Android have the option to show touchscreen activity. Turn that on. You will now see a dot when you touch the screen. Now, plug in the charger and, if you have the problem described here, you will see the dot bouncing all over the touchscreen like you are tapping all over it. It is a grounding problem. The touchscreen is getting interference from a poorly grounded cable or wall outlet.