Victor 884 Issues

[BHS Bucs]

Hi everyone -

We're a rookie team from Massachusetts - just the other day, we started having issues with one of our Victors. The students replaced it and things were fine for a bit - then the replacement stopped working. After quizzing the students working on electrical, what they can tell me is:

1. It didn't smell like burnt plastic.
2. None of the parts look melted.
3. The light no longer turns on.
4. The fan works fine.

We're puzzled (lack of experience is playing a role here!) - we've read about burning out Victors and shorting Victors on other threads... But we're not sure if that's what is happening here.

We did find some exposed wire that they have now taped, but I'm leery about putting in our last working one right now unless we can figure out what is wrong.

Thanks in advance for any thoughts!

[Mike AA]

What were they doing before it suddenly quit working? If you disconnect the PWM cable from the victor does the light flash or is it still off? IF still off likely a bad victor. What is this victor powering?

-Mike AA
Team 2015

[Al Skierkiewicz]

Sarah,
Does the fan stop turning when you try to advance the motor? I know this may sound dumb but are you absolutely sure the wiring is correct? It is very easy to swap input wires and it is equally easy to swap input and output.

There is a varied list of failures for 884:
1. Metal flakes inside from drilling, deburring or other mechanical work on the robot.
2. Wire polarity flipped (black with red or + to -) This usually results in little explosions of the power FETs.
3. Input swapped with output, results as above.
4. PWM cable not fully inserted. There should be only about 1/8" of the block showing above the molded plastic. Easy fix but watch for bent pins on the PWM cable. Also try swapping a working PWM cable to the non working Victor.
5. Improperly crimped power wiring. This can result in the fan turning until you try to make a motor move. It can easily be fixed. Wiring can be loose at the 40 amp power block, at the Rockwell terminal block or at the Victor 884. Usually this is not a catastrophic failure and easily remedied. Check all wiring by pulling, if the wire moves inside the contact or pulls out of the blocks then just reterminate.

[tdlrali]

If you found a potential short, make sure it's gone, and double check that you are not grounding anything to the frame. However, if a short was the problem, the breaker _should_ have tripped before the victor got damaged.

Are you using dynamic breaking on the victors? If the return current is too high, they can get damaged.