Technical Rotunda Tachometer Light Bulb Search

Hi, my name is Phil Severance and I own Phidon Restorations. I see that this is not a new post but it concerns a Rotunda Thunderbolt tachometer. The bulb in the face is not an incandescent light bulb but it is a neon element. You can find this bulb at any large light bulb company under the part number of A1A-E. I would be more than willing to answer any Rotunda, Ford, Cobra or Shelby question about their gauges. Thank you
Regards,
Phil Severance

 

Dear Forum responders:

I’m writing to apologize for not following up on all the great information everyone provided about Rotunda Tachs and this tiny light bulb that is odd in its behavior and electrical character for DC car circuitry. I must admit to the responders that I hoped my initial inquiry back in December of ‘22 would provide a much simpler answer about the tach bulb. After reading the responses, I was fearful that, like so many things, my quest to restore the light to my perfectly operational tach would end up with my damaging it and having to send it off to Phil for repair. In order to send the forum-requested picture of the bulb, I was going to have to disconnect the wiring, extract it from the dash, and then figure out how to get the bulb out to photograph it. Truth be told, I reasoned that my analness to get the light working wasn’t going to do anything but satisfy my obsessiveness for the tach to be “factory operational”. I never drive the car at night, so why should I risk damaging the tach if I’ll never use the light?
So, I talked myself out of messing with the tach. It looks like a pretty delicate meter, and I’d hate myself if I damaged it after 55 years of faithful service!
Phil, I will call you to see about purchasing the correct bulb. If nothing else, this thread identified the type and number of the bulb!
Thank you VERY VERY much to all who responded to help out! I hope you found some benefit from your engagement!!
Best, Bob

 

hmmm...sure looks like a good old NE-2 bulb. My vacuum tube digital clock is full of them.

 

Squirrel, I don’t know how to tell you this but your clock is wrong. It’s currently 3:32am.

 

Yeah, it's difficult to keep it on time, since I shot the video many years ago

 

Jim, you are correct. I Googled "A1A-E bulb" and it shows up as a A1A-E/ NE-2 bulb.

 

Folks:
I contacted Phil Severance of Phildon Restorations to inquire about getting a bulb to install in my Rotunda Tach. Since I failed all the great responders by not acting on your advice, I thought you might benefit from what Phil graciously shared with me about replacing this odd little bulb. Phil told me that to access the bulb, you have to take the stainless steel facia off the front of the tach. It’s held in place by small tabs that often break when they get bent upwards. Loss of the tabs means a loose tach face, requiring the facia to be replaced. Then the bulb has to be unsoldered from its leads, replaced with the new bulb, and re-soldered. Phil said you have to be very careful not to get ANY debris down in the meter mechanism or the tach will not work. So, that little bulb is quite a bugger! I’m going to leave mine alone! Phil sounds very nice and knowledgeable! A fellow I met at a car show last weekend purchased a 1963 restored Rotunda from Phil. It was beautiful. I hope this information helps someone in the future! Maybe the fellow I met contacted Phil, cause I was surprised to see his very recent post. It sure proved helpful to me!
Best to all and Thanks!! Bob

 

Those NE-2 bulbs rarely fail, I'd suspect something else in the circuit. There's no filament in a neon bulb, just two parallel wires and neon gas. Of course if the gas leaks out from a crack, then it won't work.

 

Squirrel: Thanks for that cool fact! Bob