05 August 2015

Vacuum Flourescent Display from a Toshiba VCR

On the wave of my recently born passion for neon/vacuum displays I remembered I had a VFD (Vacuum Fluorescent Display) sitting in the "might come handy" box.

The board was removed from a Toshiba VCR and it was the front panel circuitry. Under the display there is a Toshiba TMP47C1670 chip. It is a pretty complex device, probably programmable like a recent microcontroller, plus it can drive VFD natively.

How to light it up? Two things helped tracing down connections: the TMP47C1670 (partial) datasheet and a DVM.

With DVM in continuity test mode I looked for the filament. Incidentally they are the outermost pins. The datasheet provided hints on which pins drove grids (output pin called Gn) and which were for anodes. With the help of DVM I mapped IC pins with display terminals.

That was it. I fed the filament with about 4Vdc from a battery. Then my 12V PSU ground went to one side of the filament and +V to grid and anodes. Moving around grid and anode touch points I could lit all segments:

This experiment was fun and rewarding. I learned a bit more about VFD technology. Unfortunately the display has too many pre-shaped symbols that make it unattractive for reuse. It is offered free + shipping to a good home (with a documented project).