Electrical parts keep breaking!

Hi everybody, I’m new to chief delphi and FRC and I need some help with electrical work. So at the quickbuild, I think the part that broke was the Victor 888 (correct me if im wrong), its the little box that connects the mother board to the motors. So my question is: Is there a way to fix it? Or is there a place that supplies parts like these so we can get them in within the next 2 days? because we need these parts IMMEDIATELY, any help would be great, thanks!

Hi Toby, welcome to ChiefDelphi. Thanks for posting your question in the Technical>Electrical forum.

In general, electrical problems are most easily and effectively diagnosed if you provide us with as much information as possible. What about the Victor 888 in question seems broken? Can you supply us with a picture of your entire electrical setup, of the Victor 888, or more information (e.g. an unusual sound, no LED light, etc.) about your problem? You can upload pictures using the ChiefDelphi image upload tool or linking to an image on a site like imgur.

To be clear, the Victor 888 is a motor controller that looks like this. It connects the Power Distribution Panel (PDP)(this) to the motors in order to supply a specific amount of power to the motors.

As a basic diagnostic, can you tell us:

  • What color, if any, is the LED light on the Victor 888? It should be blinking or solid orange, red, or green if it’s wired correctly and receiving power.
  • What color wire is going into the “V-” screw on the Victor 888? What color wire is going into the “V+” screw? Make sure that the wires between the Power Distribution Panel and the Victor 888 go into the V- and V+ screws.
  • Do you have a cable that looks something like this going into the Victor 888? The black wire should be facing towards the inside of the motor controller.

In addition to what NWChen said:

If you need a part in the next two days, your best bet may be to see if a local team can lend you the part while yours is shipping.

Thanks for clarifying some things for me :slight_smile: Im a rookie so this will take some time to get used to. I don’t think it is the Victor 888 but it is the victor SP (http://www.vexrobotics.com/vexpro/motors-electronics/217-9090.html) product (but they all do the same thing, sorry for just figuring that out now). the problem initially was that the red 18 gauge wire wasn’t a wire at all! It was just insulation that the manufacturer put there for “decoration” so the 3 prong connector did not have to be redesigned this year. So I got somebody to open the victor up and just removed the insulation completely and connected the black and white wires with more stability. Unfortunately, after the “fixing” happened and we tested the whole electrical circuit, the untouched one was blinking orange (which was what should have happened) and the tamperd one was blinking green really fast, so I took it back to the guy and he opened it again, did some work, then tested it and it started blinking red! He said the part was done for so I held on to it for safe keeping. Was this enough description of the problem or is it too much?


Welcome to Chief Delphi, Toby.

Your team is located in Etobicoke. There are many top tier teams in Toronto and Mississauga who are likely to have the experience, knowledge and capacity to help you. The teams leading the quickbuild would be a good place to start. It may be best to meet with them in person so that they can look over your electrical system and help you figure out why you “broke” your Victor. People here on CD are more than willing to help but with some things like crossed wiring or bad connections, it is better to be able to look at it in person.

I strongly suggest that you don’t disassemble electrical components in the future as it is against the rules (R66). Also it can lead to broken parts, such as your situation.

PS The “3 prong connector” is referred to as a PWM (Pulse Width Modulation) cable.

What exactly made you want to open the Victor and start changing it’s assembly? I’m not trying to judge but I just don’t follow the reasoning of this. It was assembled that way intentionally and I don’t really see what you gain by manually modifying it. Just seems like a lot of extra work at the expense of risk with no reward.

As mentioned above though, electrical components that you plan to use on your robot cannot be disassembled or otherwise tampered with. It sounds like doing so may have broken it :frowning: When you get your new ones maybe try following someonline tutorials to make sure you have everything nailed down correctly.

First of all, thanks to everybody for all the help, it means a lot! Second, it wasn’t my idea to open the box, it was the electrical mentor at the quick build who had me do it, we wanted to find if the red wire being a decoration was just a production defect or production design (so it was really just curiosity, it was a really whacky situation). I will look for nearby teams who can lend me some temporary replacement parts and then give them back once our tests are complete, and I will not temper with any given parts now that I know it is against the rules, thank you everybody for your help, you are all amazing!

Actually R66 does allow for disassembly if your intentintion is repair. R66.M:

That said, (to the OP mainly) beware of the blue box that follows:

Basically, if you have no idea how it works inside, see if you can swap under warranty first. If a warranty swap isn’t doable, I do suggest trying to fix it on one’s free time (as learning experience if nothing else) and only using it for practice robot/prototyping purposes (unless you are very, very confident in your repair). After all, if it’s broken beyond repair and you aren’t able to warranty it out, what have you to loose?

(All of this said, if you DO know how these work and feel qualified to fix it, if you don’t mind voiding warranties, go for it, repairing stuff is fun!)

Thanks for all the info, the victor SP is broken beyond repair, so I’ll have fun taking it apart and seeing how it works, thank you all so much for your help!

The red wire is intentionally not connected because it is absolutely not required for operation. However, to stay compatible with the PWM standard spacing and connection order, the red wire was left intact.

There is plenty of documentation at vexpro.com on the Victor SP in order to assist in debug.

The Victor SPs are 100% tested before shipment so you, most likely, had an issue with connecting it to the Roborio.

You probably do not need a replacement, jut need to undo whatever the electrical mentor did inside the product.

If you need assistance with any VEXpro product you can always e-mail [email protected] or call us at 903-453-0802.


The Victor SP Quick-Start guide clearly states that the Red Wire is not used on page 3.

Most likely when the Victor was re-assembled by the mentor, the B/C Cal button was not inserted correctly. In other words the button is being held down. When a Victor SP is power booted with the button held down, it goes into factory calibration (blinking green until button is let go).

This is explained at the bottom of page 6 of the Victor SP Quick-Start.

So the problem was simply that the LED wasn’t matching your expectation? What about motor-drive? Regardless this would have been simple to diagnose and would not have required you to disassemble the Victor SP.

I’m not sure how the mentor would know this. Don’t assume that without first contacting the manufacturer.

If a product isn’t matching your expectation please contact the appropriate support channel. For example, if the Victor SP was purchased from VEX, please contact VEX’s support email.
You can also contact [email protected], but we will need to know where the Victor SP was purchased from if you email us.

I totally understand the motivation to take-apart-and-tinker, but it really isn’t necessary, we’re here to help you!

There is almost never a reason to open up any of the FRC electrical parts. It’s against R66, as somebody mentioned, and the components are usually so reliable that, if they do break, it’s probably something that isn’t worth fixing, either due to time or cost. We’ve had a similar thing happen in the past with Victor 884’s (yeah, we still have some of those for some reason) and it didn’t seem to impact their performance. My personal guess is that it has to do with the calibration of the controller, but we’ve never really had that affect the controller’s function.

I’ve been doing electrical for my team for 3 years now, so if you have any further questions feel free to PM me! I’m always happy to help. :smiley:

You may open electrical components to make repairs under the current rules. However as pointed out above, it does require some skill to get everything back in the right place to allow correct operation. FRC vendors are very helpful and as suggested by Oz and Paul get in communication with the vendor for guidance.
The red wire is part of the three wire specification as it supplies power supply to servos when used in R/C applications and FRC servos. It is not needed for motor controllers since there is a separate power connection and that is why it was not connected in your controller.

PWM cable system only need the white and black for proper communication… I believe the old motor controllers needed the red for extra power as their ability to send the pwm message was weaker than the new talons and victors

Also one thing I’ve learned being head electrical on my team is simply don’t try if you don’t know…

Electrical isn’t like programming where you can hit backspace, in electrical things can burn, arc weld, explode, and kill you.

Also I recommend tinning wires to newbs, helps them understand the wires a lot more.

I would recommend you don’t tin your PWM cables…

None of the FRC legal motor controls of the recent past have used the 5v signal wire in the PWM cable.

The way the motor controllers that I have looked at their schematics work is that the black and white wires are connected to an optoisolator. So all the signal does is light up an LED.

If by “old motor controllers” you mean the Jaguar, Vic884, Vic888, VicSP, Talon, and TalonSR… then no, the red wire is not used.

The white wire is the signal wire, and the black wire is ground. Both are needed.

The red wire is power (not signal). It is needed only when the PWM cable is connected to a low-power servo motor. It is not needed for any of the motor controllers.

The way the motor controllers that I have looked at their schematics work is that the black and white wires are connected to an optoisolator. So all the signal does is light up an LED.

The signal (white) wire carries the PWM command on it.

Yes, those motor controllers, however victor SP should not be on that list as the don’t use the red wire, it’s only there as the stock pwm they get in manufacturing is used for all their products, they just cut the red on the Vic Sp’s