Random Characters get typed

[personwholives]

Whenever I am using my touchstream lately, I get a lot of random keypresses. And not just while typing. Sometimes while I don't even have my hands on the keyboard. When it starts happening, even the backspace key produces some random letter or number. This is starting to bug me. Generally, the letters that are typed at random come from the left side of the keyboard, and are intermittent. Unplugging the keyboard or doing a palm reset usually makes the problem go away for a while, but it always seems to come back. The diagnostics don't show any errors.

This board has had issues with the ribbon cable in the past, though these have been resolved, and is on a custom stand which is a bit flimsy. I can try changing anything that might help track down the issue. I really would hate this board to die, though I suppose I could try and use it for parts to fix another board, if it came down to that. Any thoughts?

[TorbenGB]

My work TSLP acts similarly. I have to "palm" it several times daily. It seems to be mostly a question of static, and sensitivity to electromagnetic fields.

I found that removing other nearby cables helped. I have a regular keyboard on my desk as well and when I place it in front of the TSLP then the keyboard's cable hovers over the TSLP, often causing erratic behaviour. I also moved my cell phone away a bit, just to the end of the desk instead of right next to the keyboard. Also, when I've been walking in the office (we have carpeting), the TSLP is not very cooperative until I palm it.

[The00Dustin]

I try to always ground myself before touching my TSLP, both to limit this and to prevent being grounded to (and frying) one of the sensitive chips in the TSLP. That said, mine might have been doing some pretty random input yesterday, but I'm pretty sure it's weather and static related. I seldom get random stuff out of mine, and when I do, it's usually just a small amount, and not necessarily when it's being touched, but yesterday it was definitely when being touched (but not typed on). It was almost like it was picking up gestures that weren't being done. I reset mine at work fairly often when the mouse functions start acting weird (using two fingers with index as click, pinky as right click, and thumb as middle click starts to give me right click no matter what), but I attribute this to static buildup too, and sometimes a 5x palm to reset works, but I usually just go ahead and unplug and replug.

[TorbenGB]

I have my "mouse" set that way too and I see the same effects, plus when typing then random wrong characters are produced.

How are you grounding yourself? I have no useful metal parts (like a radiator I could touch) near my work desk.

[personwholives]

I usually ground myself on the computer case or the metal shelving unit. However, this morning when I walked into my office, I noticed that the unlock dialog was displayed on my computer with two random characters in it. My office was still locked, so it's not like someone else typed them or anything. As I was approaching, the escape key must have been hit, as the dialog went away. But still, that's a little weird. Could have been interference from one of the other devices on my desk I suppose, but I doubt it.... I guess I'll try moving my headphones and other things away from it....

[The00Dustin]

I also ground myself to my computer. In my office, my computer's case has a lot of plastic, so I reach to the back of it (and often get shocked, making me glad I didn't forget that time).

[personwholives]

I've been having fewer random key presses since I cleaned the board, but I'm still having the occasional issue with it. The difference is that now they're only coming from the top left side of the board, esc and 1-5, mostly. These keys are also less responsive when I type, which is starting to worry me some more. I'm occasionally getting random noisy sensors on the left side of the board as well. Since all the problems are on the left side, I'm wondering if this could still be a cable issue. Either way, I've had to switch to a more reliable board at work (my only fully functional one), and I'll have to spend some time this weekend trying to get one of my other two boards working for use at home.

I decided to rerun the diagnostics to see what it said, and this is my new result:

Code: Select all

Diagnostic Report for TouchStream ST/LP  ver 1.6:
ERROR: Left Sensor Mux Malfunctioning (Bits 0x1)
ERROR: Found 80 bad sensors
ERROR:    Run Diagnostics again, keeping surface free of hands and liquids.
ERROR:    If sensor ERRORs persist, contact support@fingerworks.com
  Sometimes cleaning fluids or hands on surface can temporarily 
   cause a few false-positive High/Low/Noisy sensor readings below.
  However, blocks of 16 or more H/L/N sensors indicate 
   hardware failure that must be repaired at the factory.
  |0      |8      |16     |24     |32     |40     |48     |56     |64     |72     |80     
0 HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH------------------------------------------
1 HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH------------------------------------------
2 ----------------------------------------------------------------------------------
3 ----------------------------------------------------------------------------------
4 ----------------------------------------------------------------------------------
5 ----------------------------------------------------------------------------------
6 ----------------------------------------------------------------------------------
7 ----------------------------------------------------------------------------------
8 ----------------------------------------------------------------------------------
9 ----------------------------------------------------------------------------------
a ----------------------------------------------------------------------------------
b ----------------------------------------------------------------------------------
c ----------------------------------------------------------------------------------
d ----------------------------------------------------------------------------------
e ----------------------------------------------------------------------------------
f ----------------------------------------------------------------------------------
Loaded 1243 Key/Gesture Mappings SUCCESFULLY
    Keymatrix#: 32
Testing Complete.

[nomaded]

I would suggest cleaning the typing/pointing surface again. I have found that cleaning them helps with stray static that seems to show up in the spring and in the fall.

[personwholives]

I tried that, not much luck. I'm going to take it home, where I might be able to work with it a bit better, hopefully. And if not, I guess I'll have to see what I can do about fixing another board.

[The00Dustin]

I'm not certain, but it seems like a bad ribon cable has been the cause of that particular section being faulty more often than not. However, it could also by that the chip used to communicate between the two boards got zapped (I'm thinking that when it gets zapped the entire left half dies, but again, I'm not sure).

[dongadoy]

After having lost two TouchStreams likely to static zaps, I've trained myself to touch a grounded wire when returning to my keyboard. So far so good.

[personwholives]

I'm not certain, but it seems like a bad ribon cable has been the cause of that particular section being faulty more often than not. However, it could also by that the chip used to communicate between the two boards got zapped (I'm thinking that when it gets zapped the entire left half dies, but again, I'm not sure).

Yeah, I was considering replacing the ribbon cable in that unit anyway. Figure I'll make a longer one to give me more positioning options, and also see if that helps with the issue. As I said before, this board has had some ribbon cable issues in the past.