New software has recently released in the last two weeks for both TZT3 and TZTXL. If mixing TZT3 with TZTXL, these newer versions are necessary. The full details of changes are posted under the product pages and listed in the software history document. For you awareness, a small software bug has come to light with the TZT3 v3.70. The good news is it only affects machines using the internal sounder with a Side-Scan Transducer connected. Those not running side scan will not see any issue. The new software causes a FALSE "fan speed" alarm after upgrading. Our parent company has quickly found the problem and a follow up version of software is coming very soon. In the meantime, if you have TZT3 Side-scan with no need to mix with XL, it is recommend that you not upgrade to 3.70 and just wait for the next version coming soon. If you have already updated, you can temporarily turn off your hardware alarms and sound until the follow up version releases. Know that it is a not a real problem with the fan.