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Severe Ghosting problem with J-PAC
BobA:
+1 for pinballjim - Isolate your jpac from any interference. Since it only gives key strokes when wires are connected then maybe the wiring is acting as rf conductors (antenna). Even better than an antistatic bag is good old metal. Place the jpac and button wire in pie tin (be sure to insulate with a sheet of plastic) I use freezer bags for temp insulation. Cover the pie tin or baking pan with tin foil. If possible ground the metal to a 3rd wire ground or a metal pipe if you have metal pipes in your plumbing. If you have newer plastic piping this will not work. This basically creates a faraday cage around your jpac and button wire.
If this works then bring your button wire outside the faraday cage to see if it will auto trigger. If it does you can try running your wire thru a ferrite core to get rid of the triggering. A couple of turns around a ferrite donut would be sufficient.
This is just testing to determine if radio frequency energy could be the cause. If it is then the source of the rf would have to be determined. Are you close to any of the following? High Voltage transmission lines, Microwave relay tower, Cell phone tower, Radio or TV transmitter tower
BuriedEgg:
Oh no! I performed the following test:
-Take one fresh wire and connect it only to the positive screw connector for P2-B6.
-Do not connect button, microswitch or Ground wire. Just one wire connected to J-PAC screw connector P2-B6 and let it hang loose at the other end.
-Connect J-PAC to laptop and move laptop to a totally different room far away from Arcade Cabinet.
-Leave text window open for 20 minutes.
Result: It typed the letter "V" all across the screen. The wire had no ground! It was acting like an antenna!
Next:
-Take J-PAC and wire and bag them in plastic sandwich bags and wrap them in a couple layers of tin foil.
Result: With the tin foil wrapped around it, it did NOT type the letter "V" anymore. Its been about 20 minutes. I'll keep testing but I'm scared about bigger things than arcade games now.
This (See Attached Image) is behind my house less than 25 feet away in our backyard!
We just had our first child. He's only 2 months old. I need to contact the County first thing in the morning. Maybe the local news station too. In the meantime, is the KeyWiz less susceptible to signal noise from things like power lines? Should I still purchase one, or just focus on getting the county to tear down those lines in my backyard?
ADDITIONAL INFORMATION:
Its been about 15 minutes since I posted the information above and I just checked it again and it indeed, HAS typed a random letter "V". I will take the whole setup to work tomorrow and try there without any high power lines to interefere.
BuriedEgg:
Thanks pinball! I'm going to buy a few of them tomorrow and put them in strategic places all over my wiring. Hopefully, that will kill off the noise hitting my wiring and I can get my game on!
AndyWarne:
There is no anti-glitch delay built into the J-PAC deliberately, so that the response is maximised. The device sends a key the instant the contact is closed, which means it has no way to know if its a glitch or not. This I consider to be the best approach for this type of device.
Keyboards have a delay built in during which time the device can decide whether this is a glitch or not. I dont know if other suppliers interfaces have a delay.
In reality I have never until now heard of this being a problem, except with dance pads, which generate masses of static electricity. For the input to be triggered the amplitude of the EMI/RFI pulse would need to be huge so there must be some serious emissions from those power lines! The pulses are probably very short though, maybe too short to cause any effect on TV reception etc.
The workaround for this is to connect 100nF disk ceramic capacitors across each of the offending switches.
newmanfamilyvlogs:
This thread has been a rather interesting read.... but if it's RF induction causing the key presses, why is it only those specific keys and not all of them? Are those wires just the longest / just the right length to 'tune' whatever is powerful enough to trigger them?
Another question, more for Andy.. Can you venture a guess as to how much power the "antenna" would have to be receiving in order to produce this effect?
And just some sheer curiosity for BuriedEgg, and a bit of a tangent: You might find it interesting to get a large loop of wire and build an 'antenna' that you connect to the microphone input of your soundcard and record a few minutes of 'air' at whatever the highest sampling rate your card can provide. You can actually monitor radio transmissions like this (though you need other equipment to monitor frequency ranges above what your soundcard samples at natively. What you'd be looking at is considered VLF or very low frequency). You might get lucky and pick up some harmonic or hint of what's there.
More info here: http://www.vlf.it/