What is the normal life span for a VFD?

All the references that I can find typically say "more than 10,000 hours' which translates to about 14 months continuous use.

There are a few patents out there that claim to extend this.

There is also alot of documentation that says the Flourescent displays life is shortened by things such as heat, etc.

As far as repairing it, it is not worth the hassle, and very difficult to find an exact match. It is better to replace the whole module.

Hello

The VFD is an electron-tube with a filament (cathode), a grid and an anode. The filament generate electrons who are transfered to the anode. The anode is fluorescence, it light up when the electrons hit it. The grid control the flow of electrons, you switch on and off the light with the grid voltage.

This was the principle. In real the filament and the fluorescence will age when you use it. The filament will burn out and the fluorescence will decrease. Thats why the light dim.

Anders

Look for any electrolytic capacitors in the drive circuit these often lead to this situation. They dry out and lower the current/voltage.