Is there a difference?

[hjl4]

Hi everyone, I seem to have hit another wall in this electronic jungle. I have a set of joysticks, that are connected to a USB port of a computer(PC) home desktop, and everything works great. My problem lye's in, when I take the same joystick and driver board, and hook it up to a new Panasonic Toughbook, and start pressing button 9 on the joystick, I get two buttons 9 and 11, that go on simultaneously. What could possibly do this??? I checked the cable and all connections.
Is the USB port on a laptop, different then the one on a desktop??
Can USB port be setup differently?
I've tried everything, even try to eliminate stray capacitance on this four layer board. (the board is just multiplexing all the switches, 12 of them).
Remember, everything works well on the desktop.
This probably isn't the best place to post this question, but it's not a project, I'm just trying to make things a little more portable here.

P.S. I tried another laptop, and same result.

 

[Sceadwian]

Are you sure it's not a driver/software issue? If not it has to be electrical, have you built this device or is it something you've modified from a consumer device? It could be a difference in the way the device is effectivly grounded when it's on a PC vs a laptop. If button 9 triggers 11, but 11 does not trigger 9 then look at button 11 specifically it's difference from 9 (not visual perhaps but on a meter. If 9 and 11 both trigger each other then look at the circuit for both of them and determine where the short of false signal is coming from. It sounds to me like a broken wire on the ground of switch 11, just off the top of my head, but there's no garuntee that's even close to what's really causing it.

 

[hjl4]

Ok thanks Sceadwian, I was thinking that also(ground issue), as the laptop is in a plastic pvc sealed box 1/4" thick. I forgot to mention also that, if I touch the solder at the joystick pins, on the circuit board, the problem goes away. The circuit board is a custom made unit from PCB Express. I will try grounding tomorrow, and hope for the best. Even an engineer took a shot at this problem, and no change. Everyone stumped.
I will find out tomorrow at work.
Thanks for response.

 

[Sceadwian]

Check the resistance of all your wires on your switches using a meter. One of them (likley the ground to switch 11) is going to read as a high resistance, either it's a cold solder joint, faulty switch or cracked wire/trace

 

[hjl4]

Ok I will check it tomorrow at work. if that is the problem, then it is easy fix.
Thankx.

I'll let you know how it went.

 

[Optikon]

If it worked fine with one laptop. Your problem is not electrical. Look elsewhere.

 

[hjl4]

Ok Sceadwian, I had time to try many different ground points, and the one that worked was the one where the shaft going thru the joystick, which is isolated by a plastic bushing, to the rest of the system. I found it strange when I would let go of the joystick, everything went haywire. When I held on to it, everything settled down. I grounded it with copper wire to the negative of power supply. Thanks for pointing me in the right direction. Problem solved.

Have a great day.