Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TubeJunkie on May 26, 2019, 06:13:45 pm
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Okay, so I've been looking at some interesting vintage amps for building, and came across this Valco Model 1215 Professional. I was going over the schematic looking at what I might have and what I would need, when I found what looks like a reference to a 220M Ohm resistor. Am I reading this wrong, and if not, why a 220M Ohm resistor? I looked on-line, and found some, and they're only about $4.00 each, so no big deal, but 220M Ohm? I've attached a couple of pics for your perusal . . . so does anyone have any insight on this? :dontknow:
Thanks.
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It says this circuit may not be changed by service technicians :icon_biggrin:
I "think" it's a floating paraphrase with NFB, other than that, if it worked then :dontknow:
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It's surely 220K.
At first I thought you found a very old plan. Through WWII, some shops wrote "M" where we would write "K". It's good Roman Numerals.
However *this* plan has K everywhere else I would expect K, "MEG" where Meg makes sense. So I think the draftsman got distracted or confused right there.
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It's 220K. Back then M was used for 1000 (like the Roman Numeral M). MEG was used for million. This schematic appears to be from a time when K was replacing M. Probably caused some confusion back then too. :icon_biggrin:
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I think the draftsman got distracted
he also lists M as Meg in the TS, I think after lunch he's in a creative frame of mind :icon_biggrin:
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This guy is really messed up. He has two 500K pots and two 1/2 MEG pots. :l2:
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looking at the text, I make him to be left handed, and until proven otherwise, a good sketch artist, so work is secondary :icon_biggrin:
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That's a lower case m. It's a 220 milliohm resistor. :l2:
It was funnier in my head.
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Here's a much better view of the confusion... :icon_biggrin:
https://el34world.com/charts/Schematics/files/Valco/Valco_valco_1215.pdf
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It was funnier in my head.
yup! I always crack myself up :laugh:
I think there's a ghost in the good view one :laugh:
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I think it was two guys working on it, or maybe the guy from MIB . . . :d3:
As noted before, there's both 500k and 1/2Meg, and the resistor in question is listed not only as 220M, but also as a 1/2V resistor.
After looking at a few other Valco schematics, and reading the above, I'm going to go with a 220k resistor.