12V Power Supply Connection to Motherboard Melted

The title sounds more dramatic than reality (although no less concerning), but the intermittent drops we had been experiencing with the 12V power supply appear to have some connection to this melted rubber over the wire connecting the power supply (V+ port) to the motherboard, as shown in the picture below.

I’m wondering if anyone has insight into:

  1. What could have caused this
  2. How we should go about repairing or alternatively, should we already consider replacing the 12V power supply
  3. How to troubleshoot and/or verify proper function following repairs
  4. If there is anything we can/should do to prevent this from happening again

Any help is appreciated, thanks!

Hi Marielle,

Wow I’ve never seen that before. It might be that the eVOLVER started drawing too much current heated the wire above the rated current. I remember you guys were trying to integrate new LEDs to the system. I have an important question:

  • Can you give me more details for what the current draw is for these LEDS/ how many you connected to the system when this happened? This is surprising that this happened.

Here are things to do to repair:

  1. Check the 12V Power Disconnect all the Smart Sleeves from the eVOLVER and power cables from the wall and make sure everything is powered down. Disconnect the 12/24V cables with a screw driver by turning on the screw terminal. Make sure the ends of the wires aren’t touching anything. Reconnect the power cable from the wall and turn on both 5V and 12V power. Check with a multimeter to see if the power is stable/ still at 12V without any connections. It is easier to verify this by placing the multimeter leads on the power supply screw terminals (not the motherboard). BE VERY CAREFUL!
  1. Add the Motherboard. After verifying that the power supply is OK on its own, it’s time to slowly add components to debug where the issue is. Take off the fan cables (the two cables stacked on the thicker cables) and only screw in the two PWR and GND cables from the 12V power. Check with a multimeter to verify the right voltage.

  2. Add the 12V Fan. I would check the 12V fan is still working, maybe with an external 12V power, if you have one. If it works, then please add back to the screw terminal where the 12/24V power goes in. Check stability of the power

  3. Add one Smart Sleeve. I would slowly add Smart Sleeves, ideally without the extra LED components connected. This can verify to see if it is the extra LED components that is causing this excess current draw.

Please let me know if this is clear and hope we can get you up and running soon.


Thanks for getting back so promptly, here are the LED specifications (we had had all 16 connected):
ITEM Size (mm): 5mm
Wire Length: 21CM
Forward Voltage (V): 12VDC
Forward Current (mA): 20mA
Lifespan: 50,000 Hours
Viewing Angle: 25 Degree
Pre-wired with built in Resistor

In the mean time, we will proceed with your suggestions for repair and troubleshooting

Okay so results from my troubleshooting:

Power Supply (Screw Terminals): 12.32 V

Power Supply + Motherboard (no fan): 12.32 V

Power Supply +Motherboard + Fan: 12.32 V

All hold steady for as long as I have left the 12V on.

Once I attach one smart sleeve (blue LED removed, tested more than one port), the voltage drops to around 10.4 V. Sometimes it bounces back, but it is definitely at this point an issue arises as disconnecting the ribbon plug consistently restores power to full.

EDIT: I found this holds true if I detach the fan wires, giving some more support to the hypothesis it may be the heating element.

I am not sure what makes the most sense to do next troubleshooting wise since there is Arduino, SA slots, and the sleeves and their hardware components themselves. I think it’s possible it may be an Arduino issue, but I do not remember if I have ever had to upload code for the spin or temperature which are the only things on the 12V at this point.

One thing I did notice was that the aluminum did seems unusually warm for how long I had the 12V on, so I am going to verify the Arduino code for the temperature PWM; but do you have any further suggestions for troubleshooting?

Does this happen when you plug in any Smart Sleeve or one particular Smart Sleeve? (e.g. is it a bad apple or something my systemic)

Some notes on additional troubleshooting: I removed the leads for the stir and temp PWMs and started up. With and without 3 sleeves attached, voltage held steady reading at 11.7 V.

Without the sleeves, the stir was a constant 11.65 V, adding the sleeves caused the voltage to rapidly fluctuate between 11.0 up to 11.7. Starting with sleeves plugged in, observe same voltage phenomena, detaching returns to stable.

The temperature PWM without the sleeves held steady at 11.7 V, as I plugged in the sleeves I could already hear the fan slowing down. With 3 ribbon cables attached voltage read steady around 9V, detaching them restored voltage to 11.7 V. Starting with them attached, the voltage initially held at 11.7 V, but then dropped after a short, holding around 8.5 V. Detaching all three sleeves fully restored voltage.

This seems to indicate the most likely culprit as something with the temperature PWM.

I tried with the same three sleeves on the same three for this troubleshooting, but yesterday used two different ones on different ports, so it does not seem to be related to sleeve or port.

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Can you pop off the pwm board for the temperature control and then retry attaching the smart sleeves? Be careful since the pins are fragile and are easily broken.

The circuit should be broken if the pwm board is not plugged in and heaters should then be disconnected. If your hypotheses is correct, should fix the weird voltage issues.

If everything looks normal after the pwm board is removed, I would try to replace that and the Arduino

Is taking out the golden leads not sufficient for breaking the circuit?

For more info, with the stir set to 0 and/or with the stir leads disconnected, if I have set the temperature to 20 C, the voltage holds steady; however, as soon as I select 30 C for positions with attached sleeves the voltage drops dramatically. Returning to 20 C restores voltage. For positions without actual sleeves attached, modulating the temperature has no effect.

With the temperature leads detached, modulating temperature does not affect anything, with or without sleeves. Without the temp leads but with the spin leads attached, at 0 spin, voltage is steady. Adding any amount of spin led to regular fluctuations: the high end was 11.7 V as expected and low end got as low as 10.8 V with spin setting 15 on 3 attached sleeves.

It seems that whenever the heating element goes on, it draws a lot of power for some reason.

Taking out the jumpers should cut off the 12V power from the PWM board, so that might tell you a bit of information, assuming there aren’t any shorts on other parts of the system.

But I think the most definitive way is to swap out the PWM board (and maybe even the Arduino) from one of the other slots (e.g. stirring or maybe one of the LED slots). And see if this still happens. It could very well be some short that might have fried the PWM board.

I swapped out the PWM, the voltage drop still occurred.

Swapping Arduino’s also did not solve the problem, and PWM_blink debug test works (and you can hear the voltage decrease and increase as the fan as it moves through the sleeves in the array plugged in vs not) and putting on 12V blue LEDs at full power with the previous PWM and other Arduino did not cause the precipitous drop.

OK bummer. It seems like there’s a short in the motherboard somewhere. Let me get a new unit prepared for your lab and send it as a replacement. I’ll message you privately once this is ready.