VRM Module not Working

Hi everyone,

One of the VRM’s isn’t working. The leds is not working and they plugged 12v fan but it isn’t work as well. And also there isn’t over heated area on vrm.

They plugged this pins in PDP.

Inside of the VRM;

They checked positive and negative pins on VRM ass well. It is working normally 12v.

Post was ctreated for @Utku

The 2 red wires makes me cringe.

You said it was getting hot right? So you are getting power to the leads. So fuse is out

Assuming you haven’t reversed polarity it is probably bad.

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Sorry not over heated.

So you aren’t getting voltage where the leads are? Do you have a multimeter to test?

If you don’t have power at the leads, check the pdp outputs for power, then check the fuses, do the other items plugged into the low amp ports on your pdp work?

Please start by using the correctly colored wires. There’s no way for us to tell if you cross wired it if the wires are the same color, and there’s a very real possibility that you mis-wired it without meaning to since the wires are the same.

After that, verify you have +12 at the end of the wires, measuring red to black. Then plug in the VRM.

Start doing things right from the very start - otherwise you’ll get all the way to the end and realize it’s a nightmare to troubleshoot.

Yes I can’t get any voltage on leads. I checked fuses and wiring. And other devices are working good.

Yeah. you are right wires can’t be same color but I don’t have black cable so I used red cable. Pdp to Vrm Cables at +12V.

Check the connection to the pdp make sure you have it in the clamping connector. If it is in good try the other low amp ports, or even a breaker port, you may have a bad port in your pdp

Maybe some black sharpie on the wire? Electrical tape? Seriously, you are asking to let the magic smoke out of your expensive equipment!


If you measured +12V on the sides of the connector (as shown in your photo), and if the polarity isn’t backwards, and if the LEDs are not coming on, the VRM may be bad. Check to be sure there is nothing shorting any of the pins on the VRM, double check the polarity, and you can also measure any voltage on the output terminals, in case something is wrong with the LEDs.

Was the VRM working before?

It would be best if you contact CTRE and describe the symptoms you observe and ask what they recommend. They may be able to suggest what caused the failure so you do not repeat it. Unfortunately, the cost of shipping from and to Turkey may be prohibitive.

Several times, I have seen in my workplace where someone initially connected something with reversed polarity, turned on the power, damaged the equipment, reconnected with the correct polarity then observed that the equipment no longer worked. By using two red wires, you have dramatically increased the probability of this scenario happening. When I only have wire of one colour, I do what Weldingrod1 suggested. If you were not the person who did the original wiring, you will never be able to know if this is really what happened.

I’ll just mention that according to the User Guide, the VRM has reverse polarity protection. So in theory you should be able to swap the wires and not kill it. Not sure how well this works in practice though.

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You are right but we never connected wires wrongly.
And the problem is not wrong wiring.

Anybody who says that is lying. The question is, was the mistake caught before or after power was applied?

(And if you then say “and we never will”, you’re next year’s wiring is guaranteed to have an issue.)

I was open the robot fuse all electronics start to work except vrm. I have never seen smoke or overheating.

Then something is wired wrong with the VRM wiring.

There’s a non-zero chance it’s your wiring, but at this point it’s most likely something in the VRM itself.

UNLESS: how many VRMs do you have on the robot? If more than one, where is the other one connected?

My experience from doing electronic R&D for many decades is that damage to electronic components does not always cause the visible release of Magic Smoke.

Was the VRM working correctly before? This is a very important question to answer before you go any further.