Video Blog 176 - HP3478A Multimeter Repair & TFT Conversion

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Published: Sunday, 15 February 2026

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DISCLAIMER: This video is educational only, so if you decide to do the same yourself then you are on your own, I can't be held responsible for any problems/issues/damage/injury that may occur if you decide to follow this blog and try it yourself.

VIDEO BLOG

Off the back of my recent HP3457A TFT conversion I was asked if it was possible to carry out a TFT conversion on it. So, I have one to hand but it needs repaired first!

The PCB gerbers, BOM, HEX file, 3D gcode/stl & instructions - https://www.ianjohnston.com/misc/3478A_TFT.zip
Steel chassis TFT mount courtesy of Hartvig: https://www.ianjohnston.com/misc/TFTholder_3478a_steel.zip
Where it all started - https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)/
XI's Protocol post - https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)/msg1347268/#msg1347268
GIT source - https://github.com/Ian-Johnston/3478A_VS_Display

Update: A user has reported that the 3478A TFT upgrade is compatible with the 3468A DMM. If you want photos of this please contact me.

Update 07/07/26:
Hex file updated - Fixed bug related to sending data to the LT7680 Pcb. Also, added speed test at boot to check for fake/slow BluePill boards.

YouTube Video:

Other user installs:
Quite a few users have installed my 3478A upgrade, including CuriousMarc -