TSP #258 - TEGAM AVM-2000 100nV - 1000V Null Detector / Nanovoltmeter Repair, Teardown & Experiments
In this episode Shahriar takes a look at a faulty PPM (TEGAM) Null Detector. With its massive dynamic range (10 orders of magnitude!) this instrument is capable of nano-Volt range measurements. Unfortunately the unit is faulty and does not display or measure anything at the input.
The unit requires a battery for operation (6V Lead-Acid) which can be bypassed by using a 7.4V LiPo battery. The unit powers on and the power supply section is fully functional. Detailed block diagrams and schematic analysis of the unit is discussed during the video.
The analog front-end is also verified to be functional through internal measurements and although there is digital communication between the various internal modules, the ADC only transmits a fixed (faulty) data sequence to the front-panel. The fault is traced to be a corrupted firmware which the manufacture does not agree to share.
Thanks to a helpful internet friend, firmware from a working unit is extracted and compared with the faulty instrument. It becomes clear that the corrupted FLASH memory is responsible. After transferring the calibration coefficients to the modified new firmware the unit comes back to life! Several measurements showcase the units capabilities and functionality.
Please consider supporting The Signal Path:
https://www.TheSignalPath.com/Donate
https://www.Patreon.com/TheSignalPath
Other links:
https://www.TheSignalPath.com
https://www.Twitter.com/TheSignalPath
Leave a Reply