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| I thinkI fried my GPWiz40MAX - Any tips to protect against ESD? |
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| laggerific:
The other day I got up from my new couch (probably need to spray it with static guard) and went to mess around on my arcade cabinet only to get a giant shock when I grabbed my metal Sanwa stick. Immediately, it appeared that several inputs were not working, some buttons, the trackball and likely the stick. I rebooted the PC and it appears that most everything survived the shock, except for one thing, the player 1 joystick inputs were now forced to the down position. Having disconnected all inputs from the GPWiz40MAX I determined the PCB to be fried, as it still showed the joystick forced into the down position. My general question is, how can I prevent a future shock from destroying something else in the future? First off, if I understand correctly, there is a difference between the common "ground" that one wires switches to, and the earth ground which helps ensure the safety of yourself and the equipment. Then to continue, if I have something like an amp powered by tapping into a molex connector does that mean the amp is grounded/earthed? or is the ground in this instance more like the commons in switches, while the amp itself isn't grounded? Should the USB cable connecting my PCBs to the PC earth the PCBs? Here is an overview of the power wirings in my cab. 3 items are receiving power from a powerstrip in the cabinet, the PC (full cased PC), the TV, and a subwoofer. The PC is the only 3 pronged outlet. The PC itself powers the following external items through a molex tap: the +12v powers the LEDs for the marquee and the amp, the +5v powers the LEDs for coin door. The powerstrip that all is connected to shows that it is not grounded, but it is "protected", although not sure how effective that is against static shock. On a side note, would there be a problem if I wired all the commons for the pushbuttons/joysticks to one common port on a single PCB even though those devices are all connected otherwise across 3 PCBs (2 GPWiz40MAXs and 1 Optipac)? |
| laggerific:
Okay...so, this clearly exposed my ignorance...but that just allows it to oxidize into understanding. That said, thanks for letting me thought dump here...I believe I do understand where I went wrong...confusing the different grounds, and assuming all was grounded okay. As is clear, I failed to do the proper earthing of all the electronic parts in the cabinet. |
| mgb:
Also if you do have a static issue in your house, maybe an antistatic mat or a spray mixture of water and liquid fabric softener will help. Besides that, you live and learn |
| laggerific:
I was evaluating my next step of ensuring that all PCBs in my cab were earthed, and have a some questions. On my motherboard, it is grounded to the case through the screw mounts and holes, which are lined with metal. But, the screw holes on the GPWiz are just green PCB. I see other holes near the bottom that appear to have metal lining, and they don't appear to have traces to them, but how can I be sure that it is being grounded effectively, or that I'm not going to short something else out? *edit* It appears that the holes with metal lining are tied to the ground used for the switches...so could I just hook a wire from the ground input and tie the other end to my PC powersupply? It seems then that we'd be tying the signal and power grounds together, which I thought was not a good thing either, but that's basically what a PC motherboard and case are doing, so perhaps I misread something in my research. Additionally, if I'm mainly trying to prevent an ESD that starts at the joystick, wouldn't it be better just to have me tie that to earth (by running a wire to PC power supply) so the ESD doesn't even consider going through the electronics? |
| lilshawn:
the GPwiz is USB, which is grounded through the usb cable to the computer, the computer is (supposed to be) grounded to earth through the metal case and the power supply (screwed to the metal case) is grounded to earth through the powercable through the powerbar WHERE IT ENDS due to a disconnected ground inside the cabinet wiring or a chopped off ground on the main power plug to the outlet itself. (your powerbar told you this through some kind of light or indicator). allways make sure everything remains properly grounded...monitor, control panel, coin door... the green wires aren't there to look pretty, they provide your static shock fried the GPWiz likely beacuse it's not designed to guard against such things, but grounding as much as you can, will increase your chances of survival. also...touch something else first... find a nice shiny metal spot, maybe a stove bolt and ground it. install it in the top of the cabinet. and just touch it first. |
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