• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Sprague/Cap Color Codes ?

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My gal bought me an organizer draw set at a garage sale earlier today. Ahh the summer treasures.

So, I got a couple drawers of old unused what appears to be sprague bumble bee's.

Trying to figure out the color codes has us pulling out each others hair!, well not really but, Its a head scratcher.

I looked up a color code chart and found one HERE, BUT, I must be missing something.
An externally hosted image should be here but it was not working when we last tested it.

I Think I get the value of 470000 MMFD (.47uf) and tolerance of 20%, But the voltage is missing a band? Or is there a no band secret?
Or have I missed the mark entirely?
Gene
 
PRR said:
> But the voltage is missing a band?

The diagram shows 1st and 2nd figure, multiply by 100.

I would assume if there is just one red band, you have "2" * 100 = 200V.

That also makes sense for 470,000pFd in that size body. It isn't big enough to be 0.5uFd and 400V or anything like that.


OK,, Got it,, But it is rather large compared to most to 400V's I have in the orange labeled spragues black tubulars. Must Be an age thing. I suppose they might be useful someplace lol
Gene
 
"That also makes sense for 470,000pFd in that size body. It isn't big enough to be 0.5uFd and 400V or anything like that."

Um... isn't 470,000pf same as 0.47uf? I find that if it can be a 0.47uf but is not big enough to be a 0.5uf, that's an odd concept.

That is a 0.47 alright. I changed out a couple of those last night in an old jukebox amp.

I agree on the voltage. Add two zeros. If there are two bands, it just means the voltage is over 900.

Yes, caps were much larger back then. In restoring jukebox amps, I often replace these, the newer caps are so much smaller they many times do not reach. The circuits were laid out with this size part in mind. I wind up having to extend the leads. On the other hand, a cap that used to sit to the side of a tube socket and went around from say pin 1 to pin 7, can with modern caps be placed right between the pins.


Back before pico was used, we did indeed call that micro-microfarad. mmfd or mmf. A lot of guys - us electronic types can be so clever - called that mickey mouse. "Gimme a 47 mickey mouse cap please." Inevitably someone would ask for a 10 mouse lytic just to be cute.
 
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