Hi there,
Pulling some dubious quality caps from a Thomas Organ, solid state made in 1972. some of them are labeled 1000, or less, and I take that to be pf. But then there are several 22k, 68k, 47k, etc marked capacitors (definitely caps, not resistors). Have any of you come across this kind of marking in caps, and if so, what would the value be? I'm guessing .0022, .0068, .0047 uf, respectively. But maybe you know? I don't yet have an LC meter.
Also, the same brand of caps apear with some different markings. I've attached a picture. I read the markings as standard - it says
p 0.10/10
250~
but I was concerned that it isn't truly .10 uf, as it is a little smaller than another .10 that I pulled off of the organ that was 160v.
Also, is ~ to indicate AC voltage, implying that DC voltage capacity may be actually about 350v?
thanks for any identifying info you may have!
Jeff
Pulling some dubious quality caps from a Thomas Organ, solid state made in 1972. some of them are labeled 1000, or less, and I take that to be pf. But then there are several 22k, 68k, 47k, etc marked capacitors (definitely caps, not resistors). Have any of you come across this kind of marking in caps, and if so, what would the value be? I'm guessing .0022, .0068, .0047 uf, respectively. But maybe you know? I don't yet have an LC meter.
Also, the same brand of caps apear with some different markings. I've attached a picture. I read the markings as standard - it says
p 0.10/10
250~
but I was concerned that it isn't truly .10 uf, as it is a little smaller than another .10 that I pulled off of the organ that was 160v.
Also, is ~ to indicate AC voltage, implying that DC voltage capacity may be actually about 350v?
thanks for any identifying info you may have!
Jeff
Attachments
do you mean .022, .068, .047 uf?
I would have guessed that as well.
Do you have a sig gen and scope and a resistor...you can find the value that way.
another way is to build an oscillator with several known values (switchable) and a compare toggle switch and listen to the frequency of the unknown values.
small amp and speaker and you will get an approximate value of the caps
I would have guessed that as well.
Do you have a sig gen and scope and a resistor...you can find the value that way.
another way is to build an oscillator with several known values (switchable) and a compare toggle switch and listen to the frequency of the unknown values.
small amp and speaker and you will get an approximate value of the caps
Having tinkered with those old organs and audio gear back then, there were weirder looking caps than that version of what became known as "greencaps" or metallised polyester film caps. Like the appearance in your pic, they were flat-wrapped and coated with a crude, matt powder coating which was in several dull colours derived from oxide pigments so they were grey, red, ochre etc. colours, marked in black printing in pF and uF in the period before nF came into general use.
The marking "0.1/10" is, of course, 100nF/10% (tolerance). "P" is uncertain - it could be a manufacturers brand or even code for that type then known generally as "polyester" but I wouldn't assume that the "~" symbol meant an AC rating like an X class cap. Markings weren't standardised to the degree they now are so treat it as a DC rating but it won't be an issue in low voltage organ electronics.
The use of k refers to 1000 pF, as you suggest and letters like J,K etc. following the value also denote tolerance.
The marking "0.1/10" is, of course, 100nF/10% (tolerance). "P" is uncertain - it could be a manufacturers brand or even code for that type then known generally as "polyester" but I wouldn't assume that the "~" symbol meant an AC rating like an X class cap. Markings weren't standardised to the degree they now are so treat it as a DC rating but it won't be an issue in low voltage organ electronics.
The use of k refers to 1000 pF, as you suggest and letters like J,K etc. following the value also denote tolerance.
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Jan Girardot may have the schematic for this organ, as he is selling off his collection at retirement. He is listed in organforum.com sale forum, music accessories and parts, with an e-mail contact to get a list of what is left. If not, the usual suppliers are covered in organforum under home organ forum. Having a schematic would confirm any suspicions of what you have. In 1972 this organ may still have significant analog sections instead of digital. The 10% tolerance is much more of a tolerance used in divider or filter analog circuits. Analog organs were full of custom value caps as the manufacturers bought large volumes and could get anything they wanted.
That said, polyester caps rarely fail in transistor circuits, especially if over specified as a 250 VAC rated one would be in a low voltage circuit. The only chance of needing the higher rating would be in the power supply as a mains spike or turn off pop suppressor cap, and in that case you would replace it with an X2 rated cap if it shorted. However, 10% tolerance in the power supply is pretty unnecessary.
That said, polyester caps rarely fail in transistor circuits, especially if over specified as a 250 VAC rated one would be in a low voltage circuit. The only chance of needing the higher rating would be in the power supply as a mains spike or turn off pop suppressor cap, and in that case you would replace it with an X2 rated cap if it shorted. However, 10% tolerance in the power supply is pretty unnecessary.
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Oh - and thanks Indianajo for your contributions to information being available on the H-100 series of Hammond organs. I picked one up last year in sort of a mystery trip (donater said it was labeled "Aeolian Hammond" and that search brought up a player-organ from the 30's) and have been trying to figure out what to do with it. possibly too big to keep and too nice to butcher.
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