> For the complete documentation index, see [llms.txt](https://docs.verifone.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.verifone.com/hardware-products/hardware/engage-devices/ux1-3-4xx-series/ux3xx/ux300-installation-guide/troubleshooting-guidelines.md).

# Troubleshooting Guidelines

This chapter lists possible malfunctions that may occur while operating a UX300-Standard device and the appropriate corrective action. If the problem persists, even after performing the outlined guidelines, or if the problem is not described, contact your local Verifone representative for assistance.

{% hint style="info" %}
The unit comes equipped with tamper-evident labels. The reader contains no user-serviceable parts. Do not, under any circumstance, attempt to disassemble the unit. Perform only those adjustments or repairs specified in this guide. For all other services, contact your local Verifone service provider. Service conducted by parties other than authorized Verifone representatives may void any warranty.
{% endhint %}

{% hint style="warning" %}
Using an incorrectly rated power supply may damage the unit or cause it to not work properly. Before troubleshooting, ensure that the power supply used to power the unit matches the specified requirements (see [Specifications](/hardware-products/hardware/engage-devices/ux1-3-4xx-series/ux3xx/ux300-installation-guide/specifications.md) for detailed power supply specifications). If not, obtain the appropriately rated power supply before continuing with troubleshooting.
{% endhint %}

## Transactions Fail To Process

There are several reasons why the card reader may not be processing transactions. Use the following steps to troubleshoot failures.

### Check the Magnetic Card Reader

* Perform a test transaction using one or more different magnetic stripe cards to ensure the problem is not a defective card.
* Ensure that you are swiping cards properly. With the card reader, the black magnetic stripe should face down.

{% hint style="info" %}
The UX300 reads the card upon card removal or withdrawal from the slot.
{% endhint %}

* If possible, process a transaction manually, using an external keypad, instead of the card reader. If the manual transaction works, the problem may be a defective reader.
* If the problem persists, contact your local Verifone representative.

### Check the Smart Card Reader

* Perform a test transaction using several different smart cards to ensure the problem is not a defective card.
* Ensure that the card is inserted correctly and that the card is not removed prematurely.
* Ensure the SAM cards are properly inserted in the cardholders and that the cardholders are properly secured (see [Installing or Replacing SAM Cards](/hardware-products/hardware/engage-devices/ux1-3-4xx-series/ux3xx/ux300-installation-guide/setup.md#installing-or-replacing-sam-cards)).
* If the problem persists, contact your local Verifone representative.


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