Reverse engineering of an Itron CH1200G VFD

I've recently started a teardown of a 5 Disc CD player from Symphonics (Click here for video) and I came across a VFD in the front panel.
With hindsight I should have measured the signals and voltages on the pins while the unit was still working but it's too late for that now.
After trying to find a datasheet with no luck, I decided to try and reverse engineer the connections and figure out how to get this thing to work. It's selection of segments are not the most useful but it will provide me with some knowledge of how to use these displays when I find something more useful.


I did a google search for how to drive these displays and found a link to Sprites mods website where he does something similar Spritesmods VFD controller page
The VFD he was using was Noritake itron branded, so hopefully some of the details will translate to my display.
The Spites mod page uses 3V for the filement voltage and 15v for grid/segment voltage so I will try and put these voltages on when I get a chance later.


As a first look from visual inspection, here is what I have mapped out. The faint lines/writing are connections I'm not sure of, the connections on the first 2 pins are not correct though.

Grid Pins

Element Pins

The 2 images above were highlighted based on the connections observed on the rear of the display (I lined up the images using GIMP to confirm which segment goes where)

Next stage is to give them some voltage :)

Update:
Just tried adding voltages to it but no observable changes :P
I will try again later.


Update (Feb 25 2015 ~12:45AM):
After watching Dave Jones' video about VFD driving I decided to get more information.

I found a circuit a page that shows you how to quickly test a VFD and it appears to work :)


Here's basically how I hooked it up. I only used a single 9v rather than 3 as shown on the page.
I only made contact for a second or 2 to see that it worked as I don't want to risk killing the display before I've had a chance to have a good play with it.

My previous assumptions that you put 3v in the first 2 pins was wrong, if I had checked it better I would have noticed that the first 2 pins are actually shorted, same with the last 2 pins.

Also looking at the PCB which I took this from, I can see that the filament drive actually comes from an extra set of winding's on the main transformer.

Now I know how to make the display light up, I will try and see if it will function with 5v driving the grid/elements since 9v worked and it was a decent intensity.
Anyway, I will keep you updated.

bye for now

Comments