> ## Documentation Index
> Fetch the complete documentation index at: https://docs.researchanddesire.com/llms.txt
> Use this file to discover all available pages before exploring further.

# High Voltage Failure

> How to fix the DC-DC converter failure issue on early Rev 2 OSSM boards when using 30V+ power supplies

## Affected boards

<Warning>
  This issue affects **Rev 2 boards with order number #1214 or lower**. If your order number is higher than #1214, this fix has already been applied to your board.
</Warning>

## Problem

When you connect a 30V or higher power supply to the board **without a motor connected**, a brief voltage spike (approximately 1 microsecond) destroys the DC-DC converter.

<Note>
  This issue does **not** occur if you:

  * Use a standard 24V power supply
  * Have a motor connected to the board before powering on
</Note>

## Solution

Add a <Tooltip tip="Transient Voltage Suppression - a component that clamps voltage spikes to protect sensitive electronics">TVS diode</Tooltip> to clamp the input spike to a voltage the DC-DC converter can tolerate.

### Required part

| Part Number                                                                            | Description | Approximate Cost |
| -------------------------------------------------------------------------------------- | ----------- | ---------------- |
| [1.5KE51CA](https://www.digikey.ca/en/products/detail/littelfuse-inc/1-5KE51CA/688036) | TVS Diode   | \~\$1 USD        |

### Installation steps

<Steps>
  <Step title="Prepare the diode">
    Bend the leads of the 1.5KE51CA diode to match the solder pad spacing on your board.
  </Step>

  <Step title="Trim the nearby pin">
    Trim the pin marked in the image below to ensure it doesn't contact the diode lead after installation.

    <Warning>
      Skipping this step may cause a short circuit between the pin and diode lead.
    </Warning>
  </Step>

  <Step title="Solder the diode">
    Solder the diode directly to the board as shown in the reference image below.

    <Check>
      Verify that the diode leads have good solder joints and no leads are touching unintended pads or components.
    </Check>
  </Step>
</Steps>