Decided today to check the tone knob since it hasn't worked since I boxed it... pot tests good, testing from solder point on main pcb.
What could be the culprit of not getting any play through the pedal for tone?
I would think bad cap, but it was fine until I boxed it and I assumed I broke the pot when I pulled on it a little aggressively.
Edit:
Pulled everything out of the box except the power/audio jacks, tone still isn't working and wiring appears fine, no obvious sign of it having grounded.
Thinking bad cap?
Which cap controls tone, I see a few in the trace diagram, looking at C13 and C14.
Both C13 and C14 are responsible for tone shaping but C14 is the "tone cap". Are you getting output despite the tone knob not working? How about your voltages on IC2A and IC2B? Do those look similar to the ones in the doc?
Maybe pot's track has crackle at one end. You won't see it but it is there, mostly very tinny. Controll with r-meter while slightly moving with pin.
Quote from: madbean on October 27, 2021, 01:20:52 PM
Both C13 and C14 are responsible for tone shaping but C14 is the "tone cap". Are you getting output despite the tone knob not working? How about your voltages on IC2A and IC2B? Do those look similar to the ones in the doc?
I get sound, volume knob works and gain also works very well. Which is partly why I waited so long to fix the tone.
IC1, IC2 all voltages are in spec. Some are .1v lower than expected
IC3 pin 7 is 7.1v when expecting 5.88, so 1v over expected.
Tone knob shows signs of a full sweep, from 0.6 ohm to just over 10k.
If I recall correctly this started after I boxed it the second or third time, had wiring break between the controls and mainboard.
One day I may replace with short ribbon cable or something stronger that can be shaped.
Quote from: Zerro on October 27, 2021, 02:18:50 PM
Maybe pot's track has crackle at one end. You won't see it but it is there, mostly very tinny. Controll with r-meter while slightly moving with pin.
Pot is dead silent, has full sweep.
Caps test as good as day 1 install...
I could try my make shift audio probe and see if anything happens.
Not finding a loss of audio on IC1 or IC2, A points for the daughterboard to connect to are fine, followed the tone path and it's getting signal, but nothing on the tone pot turns does anything.
I do have a 100k I could use to test swapping or parallel...?
No difference.
I can't find a problem before or after the tone pot.
If pot is ok and parts too, focus at continuity of pcb tracks - maybe crackles in it, mostly around solder points.
Quote from: Zerro on October 29, 2021, 11:00:25 AM
If pot is ok and parts too, focus at continuity of pcb tracks - maybe crackles in it, mostly around solder points.
I've checked around them and they appear fine, I was quick while soldering and didn't overheat.
I'm thinking is it possible for ic2 to appear to be functioning correctly, but damaged in some way?
I would think there would be no audio passing through the chain if something were damaged, I've probed with a diy audio plug and can follow sound through the tone circuit.
If I read the schematic properly input>gain>tone>output and I can clearly hear the gain side when probing through the tone stack and clean when probing from the beginning.
There has to be something damaged, maybe the input Jack came into contact after being boxed and shorted something in that area, which is why I am looking at ic2.
I used standard 1/4 jacks and input I drilled a couple millimeters higher and it's really close to the pcb.
I am thinking would to be possible to temporarily remove ic2, jumper into a breadboard and somehow test with normal transistors?
Friend gave me a few, I haven't looked them up yet, but I do want to narrow down what could be faulty and he thinks it's possible that I didn't fry it.
Very good idea - audioprobe, and trace it from start.
A couple of pics of the top and bottom of the build would help, too.
Quote from: madbean on October 30, 2021, 12:49:47 AM
A couple of pics of the top and bottom of the build would help, too.
I'll take it apart again and take some pics, quote you again when I get it done.
Quote from: madbean on October 30, 2021, 12:49:47 AM
A couple of pics of the top and bottom of the build would help, too.
Attached.
Considering taking all the wiring off, reboxing and using thick resistor legs to permanently mount the control board to the main board or something more sturdy.
(https://www.dropbox.com/s/s8mlf3gzk73mpux/IMG_6030.JPEG?raw=1)
(https://www.dropbox.com/s/swptfxdtfmfnaxl/IMG_6034.JPEG?raw=1)
(https://www.dropbox.com/s/357k3hjyowzv5ix/IMG_6035.JPEG?raw=1)
(https://www.dropbox.com/s/gc07sm6rluaedaq/IMG_6036.JPEG?raw=1)
(https://www.dropbox.com/s/g2ziiqphy1cj280/IMG_6038.JPEG?raw=1)
Did you get an audio probe made? Troubleshooting a tone issue is only a couple of parts. You did mention a possible faulty pot.
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I did, traced it all around and through the tone pot.
Tested the caps associated with tone, everything seems to be working, the pot resistance changes when turning, but no change to the sound.
I'm guessing something happened to IC2 when I boxed it and it hit a short, but hoping that isn't the case because we all know the pain of removing a IC...
Quote from: redkurn on November 10, 2021, 10:25:37 PM
I did, traced it all around and through the tone pot.
Tested the caps associated with tone, everything seems to be working, the pot resistance changes when turning, but no change to the sound.
I'm guessing something happened to IC2 when I boxed it and it hit a short, but hoping that isn't the case because we all know the pain of removing a IC...
Probe IC2 pins 1,2 6 and 7. You should have audio on them. You should be able to probe the legs of the tone pot to see if there's any change. A tone circuit is just a resistor or two and one sometimes two caps. Have you checked your resistor values intuit area?
Quote from: jimilee on November 10, 2021, 11:29:50 PM
Quote from: redkurn on November 10, 2021, 10:25:37 PM
I did, traced it all around and through the tone pot.
Tested the caps associated with tone, everything seems to be working, the pot resistance changes when turning, but no change to the sound.
I'm guessing something happened to IC2 when I boxed it and it hit a short, but hoping that isn't the case because we all know the pain of removing a IC...
Probe IC2 pins 1,2 6 and 7. You should have audio on them. You should be able to probe the legs of the tone pot to see if there's any change. A tone circuit is just a resistor or two and one sometimes two caps. Have you checked your resistor values intuit area?
Resistor values are right, this started after boxing.
I have audio throughout the circuit, before, after tone, at IC2 on all pins.
Right now I am taking it apart, going to clean, look for any signs of fault and solder it back together better since I did this nearly a year ago.
Gotcha, see if something's touching. I just didn't want you to have to go takings apart if you didn't have to. I just got out my imp. It's a treble cut more than anything. Then I discovered my bridge pickup on my 85 Les Paul isn't working. I'm hoping it's just the switch.
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Quote from: jimilee on November 11, 2021, 12:36:36 AM
Gotcha, see if something's touching. I just didn't want you to have to go takings apart if you didn't have to. I just got out my imp. It's a treble cut more than anything. Then I discovered my bridge pickup on my 85 Les Paul isn't working. I'm hoping it's just the switch.
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I've had this thing in and out of the box maybe 20 times, may as well improve the work. XD
I'd think the switch before the pup, I've looked into how long they last and usually depends on quality more than time.
I thinking cleaning up the solder joints with some high concentrate rubbing alcohol (99% Isopropyl) might be in order. Also, you have no hope of fitting that in a 1590A with those 11mm electros. You need to use low profile ones for 1590A builds. I can send some to you if you want :)
Quote from: madbean on November 11, 2021, 02:11:18 AM
I thinking cleaning up the solder joints with some high concentrate rubbing alcohol (99% Isopropyl) might be in order. Also, you have no hope of fitting that in a 1590A with those 11mm electros. You need to use low profile ones for 1590A builds. I can send some to you if you want :)
I printed a spacer for it back when I first made it, you offered to send me some then too. :D
Rebuilding the pedal now, made a really strong staple header out of thick capacitor leads.
After maybe a hour working it back into the box, the volume pot won't thread anymore, it was a pain to get back in with short leads... so if tone doesn't work I don't care anymore and will just order a new board and parts later if I absolutely need tone from it. XD
I'm done, if it works it works... otherwise it is what it is. :P
I'd add pics of the internals, it's much better than the first time I wired it and I'm glad to have a better set of helping hands that aren't the flexible kind.
Very tidy and clean, the staple header idea worked out awesome.
Something is touching on the input jack, I'll rebox it later. Tone is still out and I'm too annoyed to bother with it for a while, but I'll just get my printer working again and put it in a slightly larger box.
Trimmed the spacer down so it isn't making contact with the PCB now and the pedal at least works again, but still no tone and not going to worry over it anymore for now at least.
I'll revisit it and try to trace down the issue if I can later when I've turned my 1/4" jack with a capacitor soldered onto it into a pen and it's not as clumsy to use.
Quote from: madbean on November 11, 2021, 02:11:18 AM
I thinking cleaning up the solder joints with some high concentrate rubbing alcohol (99% Isopropyl) might be in order. Also, you have no hope of fitting that in a 1590A with those 11mm electros. You need to use low profile ones for 1590A builds. I can send some to you if you want :)
Given how this circuit works I was wondering if jumping the tone pot pins would cause a shift in tone, bypassing the knob altogether?
Got the idea while finally labeling the knobs on the mudbunny.
Rebuilt my audio probe, I can hear a tone difference when I sweep the pot on the solder joints for the pot, R20, R19, C14 and C10 have very low volume C14 after the capacitor.
I took this cap out and tested it previously and its capacitance is correct, touching the tops of the electrolytic I can hear the signal on some.
Everything from C14 back t IC2 is really low following the trace, I'll draw a line on the board schematic.
Maybe that will help work out what's wrong here.
It may be me imagining things, but I can hear a slight change when using the amp directly...
Also if anyone wants to see the new audio probe I built, it's ugly, not as crap as the original since well everything was free except the clip, the piece I used from jumper wire, super and hot glue and the heat shrink. :D
Apparently the link expires Jan. 17th, I'll update to dropbox later.
https://share.icloud.com/photos/0242nvqzXO6NR7VK-G-NklPiA
Just take multimeter with resistance meter (glyph with diode) and reflow all tracks from utmost points to others, to controll if tracks are consistent. By eye you won't see it.
Can you post pics of the front and back of your build, otherwise, we'll be guessing until the cows come home?
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Quote from: jimilee on December 19, 2021, 10:07:14 PM
Can you post pics of the front and back of your build, otherwise, we'll be guessing until the cows come home?
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See page 1, I cleaned it off like Brian suggested.
Quote from: redkurn on October 27, 2021, 04:18:39 AM
Decided today to check the tone knob since it hasn't worked since I boxed it... pot tests good, testing from solder point on main pcb.
What could be the culprit of not getting any play through the pedal for tone?
I would think bad cap, but it was fine until I boxed it and I assumed I broke the pot when I pulled on it a little aggressively.
Edit:
Pulled everything out of the box except the power/audio jacks, tone still isn't working and wiring appears fine, no obvious sign of it having grounded.
Thinking bad cap?
Which cap controls tone, I see a few in the trace diagram, looking at C13 and C14.
Gotcha, sorry about that. Tapatalk isn't showing them.
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Quote from: jimilee on December 19, 2021, 11:33:00 PM
Quote from: redkurn on October 27, 2021, 04:18:39 AM
Decided today to check the tone knob since it hasn't worked since I boxed it... pot tests good, testing from solder point on main pcb.
What could be the culprit of not getting any play through the pedal for tone?
I would think bad cap, but it was fine until I boxed it and I assumed I broke the pot when I pulled on it a little aggressively.
Edit:
Pulled everything out of the box except the power/audio jacks, tone still isn't working and wiring appears fine, no obvious sign of it having grounded.
Thinking bad cap?
Which cap controls tone, I see a few in the trace diagram, looking at C13 and C14.
Gotcha, sorry about that. Tapatalk isn't showing them.
Sent from my iPhone using Tapatalk
Can you use your DMM to test for continuity between r19 and pin 3 of the tone knob, c14 and pin two and r20 and pin 1 also? Then R20 and R22 and r20 and IC2 pin 7. I'm curious about a bad trace.
Quote from: jimilee on December 20, 2021, 12:25:17 AM
Can you use your DMM to test for continuity between r19 and pin 3 of the tone knob, c14 and pin two and r20 and pin 1 also? Then R20 and R22 and r20 and IC2 pin 7. I'm curious about a bad trace.
At pot rolled up = max tone (right)
At pot rolled down = min tone (left)
Continuity between:
R19 and pin 3 of the tone knob - yes neighbor pad to pad, through resistor no
C14 and pin 2 of the tone knob - yes neighbor pad to pad, through capacitor no
R20 and pin 1 of the tone knob - yes neighbor pad to pad, through resistor no
R20 and R22 - yes, after r20 to at start of r22
R20 and IC2 pin 7 - yes, after r20 to pin7
C14 to pin 6 - yes, after c14
At pot rolled up pin 1-3 - no
At pot rolled up pin 2-3 - no
At pot rolled down pin 1-3 - no
At pot rolled down pin 1-2 - yes
At pot rolled up resistance pin 1-3 - 9.5k
At pot rolled up resistance pin 1-2 - 1.076k
At pot rolled up resistance pin 2-3 - 8.68k
At pot rolled down resistance pin 1-3 - 9.5k
At pot rolled down resistance pin 1-2 - 0.6R
At pot rolled down resistance pin 2-3 - 9.5k
Through the pot I get continuity with it rolled all the way down from c14 to pin 1 bus side, when rolled all the way up I do not get continuity to pin 3.
Maybe I need to check the wiring, but it seems the pot internal is bad to me, unless it being 1.076k is normal between pin 1-2 when the tone is maxed.
If the pot is the culprit, can i bypass it some how for approximate middle?
I'm thinking I could by jumping pin 1,2,3 and then I would atleast not have it fully dark as it seems to be doing.
That's what it sounds like to me too. You can jumper, I think it's pins 1 and 3, that should bypass the pot, but you would need to change the tone cap too. I would replace the tone pot and see where that gets you.
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Quote from: jimilee on December 22, 2021, 01:27:32 AM
That's what it sounds like to me too. You can jumper, I think it's pins 1 and 3, that should bypass the pot, but you would need to change the tone cap too. I would replace the tone pot and see where that gets you.
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I don't have one to replace with, not sure what value would be needed, but I do have a limited amount of film caps.
10n, 100n and maybe a few others around that value.
You can add another 3n9 in parallel and see how you like it, before you go soldering and unsoldering. I'd hate to pull up some pads.
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Quote from: jimilee on December 22, 2021, 01:51:22 AM
You can add another 3n9 in parallel and see how you like it, before you go soldering and unsoldering. I'd hate to pull up some pads.
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I tacked two thick left over legs onto where pin 1 and 3 connect to the main board, and it isn't much brighter than maybe turning the tone all the way up.
Maybe I will just add a dark and bright switch externally so I can have options for now until I can get a new pot ordered.
Tried it and it sounds close enough to half or just over for me to be ok with it.
Thanks JimiLee