Luminescent or flourescent dial indicators on Fisher gear?

little-al

Active Member
So, I've just finished the restoration of my FM-50, which by the way was my first real foray into restoration work that required replacement of eletronic components. I've still got a lot to learn about the theory, although I have already learned a LOT, but I think I definitely feel a lot more confident about basic 1:1 component replacement and repair now.

The final steps were replacing the power cord and adding new X/Y caps along with a thermistor. And many thanks to all the assistance here for my basic questions. I'm sure I'll have more :thmbsp:

Everything turned out great, no more 50+ VAC on the chassis :sigh: ... no more burned out lights, and even though I replaced two of the 6AU6 tubes because two were shorted, FM reception is excellent with no alignment needed at least as far as I can tell. With its built in "volume control", it is a great little tuner to mate directly to a mono-block amplifier such as the 30-A I am currently rebuilding.


Now, that all being said, one final question though about the FM-50: Did Fisher use luminescent or flourescent paint on the white tuner dial indicator (pointer)?

I ask because I noticed a curious thing last night while showing off the now nicely lit and clean tuner to the family, which was that although the dial glass was nicely and evenly lit, the white dial indicator was essentially invisible in the dark.

Now, if you turn on the room lights, the dial indicator was clearly visible behind the nicely side-lit dial glass, but with the room lights off the indicator was completey invisible.

Perhaps Avery didn't expect one to run and adjust the tuner in pitch black :no: Perhaps, but :scratch2: :D

This makes me wonder if the dial indicator, which again is currently painted white, was also originally luminescent or flourescent? I doubt the former as usually this era of self-luminescent paint (e.g. watch/clock hands) were radioactive (which probably isn't the best idea for a receiver) and also tend to look a sickly green color in normal lighting. This dial indicator is a pure white. So, I'm wondering of the paint had originally been flourescent or reflective, but has just worn out with age?

It seems odd to me that the indicator would be completely invisible in the dark by design, intentional or oversight, even though the tuner was probably meant to be operated in SOME degree of ambient light. ...or maybe that's the answer, that the tuner was designed to be used with SOME ambient light, not pitch dark. After all, the controls aren't backlit either :scratch2:

What do you think?

The side lights I've used are new white replacement LED lights, which light the dial perfectly.

Thanks,
Al
 
I think it's normal. I noticed the same thing on my 500B.

Where did you get your bulbs? I have another tuner that needs a lamp but it's the longer one.
 
I think it's normal. I noticed the same thing on my 500B.

Where did you get your bulbs? I have another tuner that needs a lamp but it's the longer one.


I purchased them from a fellow on "the bay" with the userid "qua-co". He can make them in any standard length and in several colors and number of LEDs (intensity). He places the LEDs in a glass tube, and terminates them with copper foil.

I won't quote the price as I don't think we're supposed to talk $$ in this forum, but they were very reasonable based on what I've seen elsewhere.

His customer service was top-notch. I ordered them just a tad too long (his standard deviation once fully assembled just barely exceeded the size of the FM-50 mounts), and he was happy to recut the glass tubes and reattach the foil/LEDs for free, just as long as I covered shipping back to him. His turnaround was within a few days as well. He was a real pleasure to work with.

I've been really happy with the results.

Al
 
Thanks for the info. Both my Fishers, the left bulb was burned out. Wonder if that's another quirk like the right speaker channel seems to go out first...

Are the LED's about the same as the originals in intensity?
 
Thanks for the info. Both my Fishers, the left bulb was burned out. Wonder if that's another quirk like the right speaker channel seems to go out first...

Are the LED's about the same as the originals in intensity?


Hrmm, can't say about that quirkiness, per model, or just coincidence in your case. My two dial lights are wired in parallel on the same circuit. You should be able to see that in your schematic and tell if they are on separate circuits. But I'd be surprised.

Both of my dial lights were out, so I can't comment on intensity. The LEDs are plenty bright though, and they look good. They might be a tad whiter than an incandescent I suppose. So side-by-side I suspect real lamps are probably "warmer" looking. You can get the LEDs in green, blue and I think a yellow color, but the white looked best to me. I got the green too, but that washed out some of the dial glass printing, although it did look kinda cool in a way. I went back to the white though.

Al
 
To my knowledge the use of tritium or other isotopes on dial indicators at FISHER wasn't done. I've never come across a FISHER dial indicator that had any luminescent property, and my gear ranges from 1951 to 1969. If you have a signal strength meter on the FM-50 it should back bounce some light across the dial behind the glass to illuminate the indicator somewhat. The STEREO BEACON Tuning tube probably doesn't put out enough back scatter to illuminate the indicator. If not then all the illumination will come from outside sources for the indicator to reflect off of.

Larry
 
I have an FM-200 that was modified by a previous owner with a tiny red LED on the tip of the dial pointer.
 
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