Thread: PCM Brownout
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Unread 24-02-2016, 11:48
BOSS BOSS is offline
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PCM Brownout

We are having a slight issue with our PCM see below. Has anyone else had this issue see below.

We have noticed during this build season at times that the PCM would alternate between green and then flash red and yellow for a second or two and then return to green. Initially we didn’t really pay much attention to this as it didn’t seem to be causing issues during initial testing. However once we completed the robot and were relying on solenoids and the compressor heavily it has become a serious issue.

The issue in the PCM is occurring only when our motors are running at full speed in either direction and then the joystick is released quickly causing the motors to stop suddenly. As soon as that occurs the PCM lights will alternate red/orange and then return to green. While this is happening the compressor will not activate and essentially all functionality on the PCM is nonfunctional until the unit apparently resets and returns to green. If we take it easy on throttle release this issue will not happen.

We have done the following.

1. Checked and rechecked all wiring on the entire robot

2. Relocated the robot wireless radio over 10’ from the PCM

3. Replaced the Canbus wiring

4. Temporarily moved the PCM power input to a standard 20 amp output on the PDP

5. Increased the 18g wire feeding power to the PCM to 16G

6. Replaced the module with a spare from last year’s robot

7. Ensured the battery in the robot is fully charged and is also a new battery.

8. Ensured that firmware is up to date on all components.


All of these attempts do not change the issue.

As a last test we moved the PCM power input off the robot and went directly to another robot battery outside of the robot not connected to the PDP. This step obviously cannot be maintained for competition but absolutely made the PCM function 100% correctly.

This issue seems to be some type of voltage change issue to us (brownout, spike, etc)

We cannot think of any other things to try to resolve this issue.