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Unread 03-07-2012, 08:10
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Re: Spikes not working - URGENT

For future reference, seating PWM cables into a spike are a real PITA. Back when I was still wrestling with the IFI system in the pits, we had just one spike that refused to work properly. It would operate our pneumatics, but only in one direction. After wrestling with it for half an hour (compounded by the fact our electronics were mounted vertically underneath our robot's arm).

Turns out just one of the pins was not seated properly. Talk about 30 minutes of debug wasted [an important lesson learned].

Something you can do to make sure the PWM cable is seated properly is to remove the top portion of the spike case (I don't remember any warranty stickers attached here). If you tug on it a little, the top will come off. Then you can actually see the terminal, and if you thread the PWM cable through the top of the case and see it plugged in, you won't have to worry about it being seated properly. Then you can push the top of the case back on, strain relief the cable and forget about it.
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Unread 03-07-2012, 14:12
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Re: Spikes not working - URGENT

Quote:
Originally Posted by apalrd View Post
We use clear silicone bathroom caulk (it comes in a nice toothpaste-ish tube) for all PWM and other signal wire connectors, plus black duck tape on the radio. It's fairly sticky, and fairly easy to remove.
From what others have told me, some silicone products (like marine silicone sealants) produce corrosive gases while curing so it is best to use silicone products designed to be compatible with electronics (which will not produce the corrosive fumes). The spikes' PCBs are coated so that might protect them to some degree, but the PWM connector left unprotected since the coating would render the connector useless.
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Unread 03-07-2012, 15:46
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Re: Spikes not working - URGENT

Quote:
Originally Posted by PAR_WIG1350 View Post
From what others have told me, some silicone products (like marine silicone sealants) produce corrosive gases while curing so it is best to use silicone products designed to be compatible with electronics (which will not produce the corrosive fumes). The spikes' PCBs are coated so that might protect them to some degree, but the PWM connector left unprotected since the coating would render the connector useless.
The polymerization reaction of consumer-grade RTV silicone caulk and adhesives outgasses acetic acid. Although it is a weak acid, it is an acid nonetheless, and could cause corrosion if trapped against metal.


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Unread 03-07-2012, 22:27
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Re: Spikes not working - URGENT

This is more of a reminder of the values of a well organized and carefully built electrical system (I apologize for going a bit off topic, but these tips will make any future troubleshooting easier and faster):

Troubleshooting an electrical systems can cause a lot of headaches and take up valuable time during build season and at competition. The best way to troubleshoot a good electrical system is to start before the first wire is crimped. If you start with an organized and careful approach, you can save a lot of time in the long run. Two of the easiest ways any team can do this is label every wire and component, and test and check wires multiple times before adding them to the system.

Effective labeling is a must for any electrical system. This means to label both the components and the wires, and stick to a system for all labels. For example, my team labeled all jaguars with a number, all victors with a "v" followed by a number, all spikes with a "s" followed by a number etc. This helped the electrical team to easily identify what each wire was connected to and allowed the programming team to figure out what controlled things such as motors by looking at the motor rather than tracing the wire from the motor back to the speed controller. A quick tip for labeling is to label each end of the wire and label each wire individually, instead of using the same label for things such as power and ground wires on the same component.

Proper wire construction is the cornerstone of a solid electrical system. PWM wires can be very temperamental to build, as an improper crimp can be easy to make and hard to detect, but these tips can apply for all wires. First off, it is very easy for anyone to make a mistake when crimping a PWM pin. Crimp too much of the housing and not enough wire and the wire won't conduct properly, and crimp too much wire and not enough housing and the pin can easily snap off. To remedy this, after a visual inspection, use a multimeter to test a crimp both before and after placing the pin in the housing to make sure that the pin is conductive. If its not at either time, then it's back to square one, better to be safe than sorry.

Taking these extra steps will take extra time and patience, but it is well worth it, considering how it will better prepare you for the season ahead.
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