Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: PGadd on April 04, 2020, 10:40:04 am
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Good Day,
I"m having a time trying to identify this resistor. What am I missing? It appears to be a 5 band, but makes no sense to me.
brn, blk, gld, slv, blu? The inverse doesn't seem to work either. When I ask it what it is with a ohm meter, it says. " Hey dude I'm done resisting, and from now on I am an open circuit, don't judge me..........."
Paul
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got a pic of the circuit it came from, the circuit ballpark age??
in the 'ol days caps and inductors could be found that look like R's
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Brilliant. It's on the right in the pic. Between line in and a rectifier.. can you help with the value? It's a driver for a ultrasonic cleaner transducer. Maybe 60s?
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take the same quality pic of the foil side, i'll get out my crayons and guess :laugh:
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Very cool thanks. The best I can come up with is 1uh but the blue band is making me unsure. Every Henry I know are so hard to guess at, even the micro ones. Thanks so much for the help.
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Henry I know
the thing about Henries, they should move a meter, caps, not so much, so there's the "problem", I call it the 50/50/90% (you're wrong:)
I'm printing 'em out, how good are you, make a homemade schematic and we'll compare notes :icon_biggrin:
might be a couple days for me, life
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pass 1, not verified, partial, typically 3 before I get close enough :laugh:
I'm going to play with crayons now
the .sch needs software, good free schematic drawer, tedious at times :icon_biggrin:
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Just like you, I’m confused by the sequencing, and also the presence of what would typically be two tolerance colors / bands.
Like shooter, I have seen axial capacitors in older gear, but I recall them having rounder ends, and not being shaped that much like a standard carbon comp resistor, as in your pic. I can’t be sure, but I do think this is a resistor.
But here are a few wild guesses, basically shots in the dark.
Does a really high resistance make sense in this part of your circuit? Ignoring silver and gold, and their out-of-order placement, what about brown-black-blue, or 10 million ohms a.k.a 10M?
And just wondering if your meter measures resistance at 10M and above? If not, would it read a 10 Meg resistance as open circuit, per your stated reading?
One other, final guess. Silver AND gold together might possibly mean 10% + 5% = 15% tolerance? Never seen that before, but maybe.
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It's a 1µH 10% inductor. Replace with a wire jumper unless this is mission critical. If that's the case, look in the T.O. for part number.
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Steve, I think you’re right. Probably an inductor. I don’t have much experience with inductors, beyond my wah pedals. But out of curiosity following your post, I googled for inductor color band codes. They seem to align better with the pattern on this part than my wild resistor guesses.
However, I still see some questions here.
The only example I found that allowed for gold in the third, 10X multiplier spot, suggests that it means you DIVIDE by 10.
So maybe 0.1uH (at 10%, per the silver band)?
And I still don’t know about that blue band. Temp rating or current rating or ???
Anyway, here is a link to the table I found which mentions gold in place three (other sources did not acknowledge it):
https://www.electronicshub.org/wp-content/uploads/2015/09/image-3.jpg
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The only example I found that allowed for gold in the third, 10X multiplier spot, suggests that it means you DIVIDE by 10.
Divide by 10, multiply by .1, all the same.
Band 1 = first digit = brown = 1
Band 2 = 2nd digit = black = 0
Band 3 = multiplier = gold = 0.1
So, 10 times .1 = 1
This is exactly the same for resistors. A 1Ω resistor is brown-black-gold.
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Oops. Self-directed face palm. I was stuck thinking this was all mysterious and complicated, when I just needed a refresher in 10 / 10 = 1. Thanks Steve.
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the thing about Henries, they should move a meter, caps, not so much, so there's the "problem", I call it the 50/50/90% (you're wrong:)
So I should mention, that there are two PCBs and transducers, repair was necessitated because one of the piezo transducer arced to ground and took out the transistor and the inductor in question. With out doing a visual inspection, I hooked the good PCB to what was in hindsight, a cracked plate on the bad PCB's trasducer and killed the good board..................
how good are you,
Depends on who you ask, (please don't ask my girlfriend) I've never drawn schematics,but thanks for the challenge, I'll give it a go.
Like shooter, I have seen axial capacitors in older gear, but I recall them having rounder ends, and not being shaped that much like a standard carbon comp resistor, as in your pic. I can’t be sure, but I do think this is a resistor.
But here are a few wild guesses, basically shots in the dark.
Does a really high resistance make sense in this part of your circuit? Ignoring silver and gold, and their out-of-order placement, what about brown-black-blue, or 10 million ohms a.k.a 10M?
And just wondering if your meter measures resistance at 10M and above? If not, would it read a 10 Meg resistance as open circuit, per your stated reading?
I was going down that same road but it just didn't make sense. Yup my trusty old Fluke reads into the millions.
I'm going to play with crayons now
Nice.
Ya I'm going to work on that if I can find my crayon sharpener
It's a 1µH 10% inductor. Replace with a wire jumper unless this is mission critical. If that's the case, look in the T.O. for part number.
Alas, I can't find schematics or a parts list for this board.. but I'm going to try the jumper.
I must say that this community has been an awesome experience, I'm just a hobbyist who likes to fix things rather that toss them away. and have been playing with repairing and modding PCs lately, but in that world, if you even mention something like a through hole component or something that more that five years old, they look at you with pity in their eyes. "Why don't you buy a new one with pretty flashing lights"
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I'm going to try the jumper.
try a 24 - 30 gauge strand, works as a poor mans fuse
I got started in Electronics after the gods re-set it to "modern", so pre '70s never got glued in my head :laugh: