This article will help you diagnose problems with a DM24 digitiser, where
The DM24 digitiser is available as a stand-alone unit, integrated into instruments (such as the 5TD) and integrated with acquisition modules (such as the DM24S3EAM or the older DM24S3DCM). The DM24 underwent a significant design change in late 2005, when the Mk3 was introduced, but there are still many Mk2 units installed and giving good service. The two versions require different firmware. This page describes how to tell whether you have a Mk2 or a Mk3 DM24 digitiser. Read more...
Güralp DM24 digitisers manufactured after 2005 are of the Mk3 type. Firmware for these modules has a version number above v.100.
This document provides upgrade instructions and release notes.