How to fix a problem spike

[Thad House]

Today 2 of our spikes went bad, and we would like to know how to fix them if it is fixable. One of our spikes consistently lights up red, and another once consistently lights up green. I opened one of them up, and I cannot see any solder bridges, so I was wondering if it could be internal in the relay modules. Any ideas or should i just wait until tomorrow and call vex?

[marccenter]

Team 4488,

In my experience as an engineer it is unlikely that 2 components have failed due to themselves.. Can you post a little more information about your wiring configuration, what you are trying to do and your software so we can possibly point you in a direction?

[Thad House]

They were hooked up to the compressor, and after a few minutes it is doing what i described. We know it is not a wiring issue because we hooked the compressor up to another spike and it works and is still working hours later. So we have it working now, but are just wondering what to do with the old ones.

[Thad House]

So we now have a 3rd dead one out of the box. We will be calling vex tomorrow and see if they can help.

[Gregor]

3 dead spikes sounds like an issue on your part. Can you describe your wiring, and please include pictures?

[Thad House]

I don't have pictures, but it uses 18 awg wire from a 20 amp breaker going to the spike, then the output is wired to powerpoles which then go to the compressor. Its wired correctly. Thats how we have done it for years. We are using the new smaller compressor. And as of now a new spike is working correctly wired the exact same way.

[Al Skierkiewicz]

If you have not replaced the fuse in the spike with a breaker you have simply blown the fuse in each spike. The compressor draws significant current when it starts. It is legal and recommended that you replace the fuse on the spike used for the compressor with a 20 amp breaker.

[Thad House]

We were using breakers in 2 of them, and a fuse in one of them. In the one the fuse was in it was still good and was not blown. Plus if we pull the fuse the light turns off like it's supposed to.

[jwakeman]

I believe I found a bad spike last night while trying to get our compressor running. The behavior i saw from the spike is similar to what the original post described. Here is what my experience was:

1. Using 20 Amp snap breaker in the spike. Using the Compressor class in WPILib. Before the robot was enabled, solid orange LED on the spike. Once the robot was enabled the Compressor code would turn on the relay on the DSC (confirmed, little green light lit up as expected) that the spike was connected to. This resulted in the LED on the spike turning off (no color).

2. Removed the compressor leads from the output side of the spike. No change. Spike LED still off.

3. Removed the pwm cable from the spike. LED turn RED. Measured -10V on the output of the spike.

Replaced the spike. All worked fine. I did notice the pins on the pwm were pretty mangled when i removed it from the spike the first time (step 3 above) and it is possible not all three pins were seated correctly and this may have had something to do with the failure of the spike.

[Al Skierkiewicz]

Ok,
I am going to state this as it is not entirely obvious. The input to a spike uses the same cable (PWM style) but does not feed a PWM signal to the spike. If the spike is not changing state as the LEDs next to the relay outputs on the DSC, then the likely culprit is the PWM style cable. Unlike the PWM outputs that feed a Victor, the center pin is used for the relay outputs.
Theoretically, the spike should not lock to an output when the cable is pulled. So as you have found, the spike operated normally when replaced.

[jwakeman]

Originally Posted by Al Skierkiewicz

Ok,
I am going to state this as it is not entirely obvious. The input to a spike uses the same cable (PWM style) but does not feed a PWM signal to the spike.

Understand it is not a pwm signal and that we are just using the same cable that is used to transfer pwm signal to the other motor controllers.

Originally Posted by Al Skierkiewicz

If the spike is not changing state as the LEDs next to the relay outputs on the DSC, then the likely culprit is the PWM style cable. Unlike the PWM outputs that feed a Victor, the center pin is used for the relay outputs.
Theoretically, the spike should not lock to an output when the cable is pulled. So as you have found, the spike operated normally when replaced.

Not sure I fully undestood. You are confirming that the spike was bad?

[Jon Stratis]

Originally Posted by jwakeman

I believe I found a bad spike last night while trying to get our compressor running. The behavior i saw from the spike is similar to what the original post described. Here is what my experience was:

1. Using 20 Amp snap breaker in the spike. Using the Compressor class in WPILib. Before the robot was enabled, solid orange LED on the spike. Once the robot was enabled the Compressor code would turn on the relay on the DSC (confirmed, little green light lit up as expected) that the spike was connected to. This resulted in the LED on the spike turning off (no color).

2. Removed the compressor leads from the output side of the spike. No change. Spike LED still off.

3. Removed the pwm cable from the spike. LED turn RED. Measured -10V on the output of the spike.

Replaced the spike. All worked fine. I did notice the pins on the pwm were pretty mangled when i removed it from the spike the first time (step 3 above) and it is possible not all three pins were seated correctly and this may have had something to do with the failure of the spike.

Could it have something to do with the way the PWM cable was seated in the Spike? I haven't opened one up for a couple of years, but if the pins find their way to contacting control components that they shouldn't, it possible to fry something with an unexpected 5V signal...

[burde1jb]

I'll post here as it seems as fitting as anywhere...

Team 4327 had similar problems with a spike relay connected to our compressor. First, the symptoms:

-Spike relay (new) will work initially. This lasts for about two matches. Using 14 awg wire. Code operates such that whenever teleop is enabled, the compressor is to run until reaching 120 psi (I think this is standard, but this is our first year with pneumatics and therefore I am no expert in this field)
- After about two matches, the compressor does not turn on when teleop is enabled. The light on the spike relay is OFF. When the PWM cable is removed, the light is RED.

Now, the fixes we attempted...
-Fuse is not blown. Replaced with the circuit breaker usually used on the power distribution board.
-Checked the PWM cable. Moved to another spike relay on the robot (indexing wheel) which then runs constantly (as programmed thinking it is the compressor).
-12V received and 11V coming out when the PWM is not plugged in. Cannot remember if/what/how much when PWM is inserted.

We went through 3 spike relays at the Gull Lake event scratching our heads over this business. We would like to know a way to test if our old spikes went bad or if we're just plain dumb about something.

Any help/advice from you wise ones would be appreciated. Thanks ahead of time!