Help with resistor replacement
#1
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Help with resistor replacement
Hi everyone, sorry to drop bomb a question on new forum. (not comfortable carry out this repair without some knowledgeable advice)
I've identified 3 resistors in my guitar amp that are faulty and need replacing, took them out and I wasn't having much luck identifying their rating, only place in town that could help me didn't have the same ones and he's given me some that are slightly different, said they should be fine...
I'm not comfortable fitting these because after trying out some online rating calculators Ive come out with the results of 22k ohms 5 colour bands being replaced with 2.2m ohms 4 colour bands (correct me if im wrong), Ill attach a picture of both old and new.
Any help would be much appreciated, and im happy to provide more info if required.
I've identified 3 resistors in my guitar amp that are faulty and need replacing, took them out and I wasn't having much luck identifying their rating, only place in town that could help me didn't have the same ones and he's given me some that are slightly different, said they should be fine...
I'm not comfortable fitting these because after trying out some online rating calculators Ive come out with the results of 22k ohms 5 colour bands being replaced with 2.2m ohms 4 colour bands (correct me if im wrong), Ill attach a picture of both old and new.
Any help would be much appreciated, and im happy to provide more info if required.
#4
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Hi Jackson and welcome to the forum.
You are correct, that would not be a good replacement. What you want is a Red, Red, Orange for the first three colors. The fourth color is a tolerance so gold or silver would be fine but your 5* may be signifying 5% so gold if you can find it.
Note his Red, Red, Green is 22 times 10 to the 5th power or 5 zeros, thus the 2.2 meg you stated. (that's for other readers in the future).
Bud
You are correct, that would not be a good replacement. What you want is a Red, Red, Orange for the first three colors. The fourth color is a tolerance so gold or silver would be fine but your 5* may be signifying 5% so gold if you can find it.
Note his Red, Red, Green is 22 times 10 to the 5th power or 5 zeros, thus the 2.2 meg you stated. (that's for other readers in the future).
Bud
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Too hard to see on my phone, I can only see color 4 bands, I can't tell which ones in the pic are 4 bands and which are 5. Here's a link to an online calculator that should help you. Just click the correct button for the # of color bands:
https://www.digikey.com/en/resources...or-code-4-band
Edit: In rereading your post, I see that the old ones on the bottom have 5 bands. They are very different.
https://www.digikey.com/en/resources...or-code-4-band
Edit: In rereading your post, I see that the old ones on the bottom have 5 bands. They are very different.
Last edited by JoeWilson; 08-28-17 at 05:21 AM.
#6
Short answer: You would want to find resistors with the same color band pattern.
I see the old resistors on the bottom with just 4 bands, and with a value of twenty two ohms and not 22K.
(Starting from the end with a non-metallic band, red for 2, red for 2, black for add no zeroes.)
The gold band further on stands for resistance value plus or minus 5%.
Double check the schematic or parts list or circuit board markings.
Don't forget that, when measuring resistance, turn off the power and also one of the two places you touch the meter probes to must be unhooked from where it was connected (or if it is a terminal, have all other wires unhooked from it.)
I see the old resistors on the bottom with just 4 bands, and with a value of twenty two ohms and not 22K.
(Starting from the end with a non-metallic band, red for 2, red for 2, black for add no zeroes.)
The gold band further on stands for resistance value plus or minus 5%.
Double check the schematic or parts list or circuit board markings.
Don't forget that, when measuring resistance, turn off the power and also one of the two places you touch the meter probes to must be unhooked from where it was connected (or if it is a terminal, have all other wires unhooked from it.)
#7
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Now confused as he posted "on the parts listing of the circuit board, the original resistors are listed as, 22k-1/4w-5*"
I agree, if those are the ones he removed they are not 22K.
Bud
I agree, if those are the ones he removed they are not 22K.
Bud
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Now confused as he posted "on the parts listing of the circuit board, the original resistors are listed as, 22k-1/4w-5*"
I agree, if those are the ones he removed they are not 22K.
I agree, if those are the ones he removed they are not 22K.
A 4 band Red, Red, Green, Gold is also a 2.2M, so they'd be the same.
If the old ones were 5 bands (Red, Red, Black, Yellow, Gold), and the new ones have 4 bands (Red, Red, Green, Gold) they are the same.
#9
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I never had 5 band resistors to work with so not used to the separation between bands, but I enhanced that image as best I could and a fifth band did not show up. My guess is those bottom resistors are 22 ohms and that leaves the question as to what the parts listing is vs what was on the board. Certainly wouldn't want to install 22 ohms where a much larger resistor should be.
I'll wait for Jackson to clarify.
bud
I'll wait for Jackson to clarify.
bud
#10
The picture is of the ones he received as replacements.
He needs the 22k @ 5% which is the red-red-orange-gold.
Pretty rare for a 22k to go bad so be sure to check yours with one side disconnected.
He needs the 22k @ 5% which is the red-red-orange-gold.
Pretty rare for a 22k to go bad so be sure to check yours with one side disconnected.
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Champions, thanks for the reply.
Ive just noticed the schematics are from 1999, and this is a far more recent model. (always good to check the fine print, trying to find more recent prints)
*Regardless, Im definitely taking the option of replacing them with identical resistors as the ones removed*
The lady at our local Jaycar is able to order in some, but she says she needs to know which ones they are (its at this point I got confused) I've tried the online calculators, and there doesn't seem to be and option for 5 band resistors with white as the 5th band, so I've entered in as 4 band (Red, Red, Black, Gold) and its results show..
22ohms 5%... once again, this is disregarding the white band.
So basically my final questions, Is 22ohms 5% what I request at Jaycar, or eBay as another option, Or are these resistors identified with another specific name/listing?
Thanks again guys.
Ive just noticed the schematics are from 1999, and this is a far more recent model. (always good to check the fine print, trying to find more recent prints)
*Regardless, Im definitely taking the option of replacing them with identical resistors as the ones removed*
The lady at our local Jaycar is able to order in some, but she says she needs to know which ones they are (its at this point I got confused) I've tried the online calculators, and there doesn't seem to be and option for 5 band resistors with white as the 5th band, so I've entered in as 4 band (Red, Red, Black, Gold) and its results show..
22ohms 5%... once again, this is disregarding the white band.
So basically my final questions, Is 22ohms 5% what I request at Jaycar, or eBay as another option, Or are these resistors identified with another specific name/listing?
Thanks again guys.
#13
Pretty sure those are standard 4 band resistors.
A guitar amp would not usually need 5 band precision resistors.
Based on your picture..... you need 22 ohm 1/2 watt 5% resistors.
From Jaycar... jaycar/22-ohm-0-5-watt-metal-film-resistors/RR0532
It is extremely unlikely that the design changed from 22k ohms to 22 ohms. The k probably should have been ohms and the improvement would be from 1/4w to 1/2w size.
A guitar amp would not usually need 5 band precision resistors.
Based on your picture..... you need 22 ohm 1/2 watt 5% resistors.
From Jaycar... jaycar/22-ohm-0-5-watt-metal-film-resistors/RR0532
Ive just noticed the schematics are from 1999, and this is a far more recent model.
#17
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As others already mentioned, it is very rare for resistor to go bad unless it is burnt, which will show visible signs.
How did you come to the conclusion your resistors are bad?
How did you come to the conclusion your resistors are bad?
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Someone online had the same problem and he identified 3 faulty resisters (labelled r18,r107 &r108 on the circuit board). This amp belongs to my cousin, its the same model as mine, so we swapped out circuit boards to narrow down possibilities, and could confirm that it is the board that the 3 resistors are on, so in good faith we're just gonna replace them and hope for the best, and yeah.. the guy at the auto electrical place tested them with a multi-meter and 2 out of 3 are faulty. He got out the 3 with green bands and said that's the closest he had.
As soon as the replacements get in I'll post the results.
As soon as the replacements get in I'll post the results.
#19
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I have years of board repair experience as do others here and yes you can have a bad resistor, but no it did not fail by itself. If a resistor is cooked something else took it out. (99% probability)
As for "the guy at the auto electrical place tested them " I would have no confidence in his advice.
Bud
As for "the guy at the auto electrical place tested them " I would have no confidence in his advice.
Bud