I built a GGG companion fuzz months ago and it's been working great until today.
I was reorganizing some pedals tonight, using a boss daisy chain to power the pedals. The companion fuzz was already plugged in, but as I was plugging in another pedal, the tip of the daisy chain hit the enclosure causing a small spark and all the pedals turned off for a second. I'm not sure if this is the cause to my issue or not, but I'm wondering if maybe I caused a little power surge.
All my pedals work fine except the companion only works in bypass mode now. One of my capacitors is only rated at 10v... Do you think the surge maybe blew out the cap? I have some 16v ones of the same value laying around, maybe I'll try those.
Ugh, maybe it's time I buy and learn how to use a multimeter on pedals.
Bump, any help would be appreciated.
Thanks.
Here's a good place to start:
http://www.diystompboxes.com/smfforum/index.php?topic=55003.0
Quote from: GGBB on June 07, 2012, 10:56:08 AM
Here's a good place to start:
http://www.diystompboxes.com/smfforum/index.php?topic=55003.0
Thanks! great thread! From reading this I'm hoping I was right and I blew the 100uf 10v cap. Since I have 100uf 16v already :)
Quote from: StevenJM on June 07, 2012, 11:15:00 AM
Quote from: GGBB on June 07, 2012, 10:56:08 AM
Here's a good place to start:
http://www.diystompboxes.com/smfforum/index.php?topic=55003.0
Thanks! great thread! From reading this I'm hoping I was right and I blew the 100uf 10v cap. Since I have 100uf 16v already :)
Does your GGG pedal have a reverse polarity protection diode? I don't see one on the schematic. Sounds like you fried some active components by accidentally shorting out your power supply. I really doubt it's your 100uF cap.
^^^ +1
The 100uF cap is a typical power supply filter cap connected between +9v and ground. If it fried you might actually be able to see that visually (blown top, burn marks, bulging). Otherwise, you can easily test it for being shorted with a multimeter. If it's not shorted out, even if it has failed it wouldn't keep your pedal from working so you likely have some other problem(s).
The reason I think it's not the 100uF cap is that it would have to be in a reverse polarity situation for more than just a few seconds to get blown. It only takes a second to blow active components that aren't protected from reverse polarity however.
I agree Paul. For the record, the GGG schematic doesn't show them, but the bill of materials and parts layout both have the 100uF power filter cap and the reverse polarity diode.
Quote from: GGBB on June 07, 2012, 12:54:13 PM
I agree Paul. For the record, the GGG schematic doesn't show them, but the bill of materials and parts layout both have the 100uF power filter cap and the reverse polarity diode.
OK, good to know. That makes this event even a little more unusual...
Man what else could it be? Nothing looks visually burned when I opened it, it was working fine prior the "spark" that's why I'm assuming that's the cause. I checked all the wires and my connections are all strong.
Thanks for looking into it for me though, it's a head scratcher.
The only way you'll figure it out is to get a DMM and measure voltages. Then you can determine what is getting power and if the voltages look right.
Walk me through it quick :). I've used one to test guitar connections but never a circuit board...
Should I plug the power supply into the pedal, and just test which active parts aren't getting power? Black to the ground and red to the positive side of the cap?
You're getting the idea...
well i switched out the 100uf 10v cap and still doesn't work. Now the LED isn't even working. Still works when bypassed though.
bummer.
I love the audio probe as described in the debugging page. I would "listen" to Q1's base, Q2's base, Q3's base. That will tell you what stage is not working. Then figure out the problem from there. If the LED is not working, it could be some sort of power problem. Check the voltage going to the LED.
Quote from: aron on June 08, 2012, 12:56:12 AM
I love the audio probe as described in the debugging page. I would "listen" to Q1's base, Q2's base, Q3's base. That will tell you what stage is not working. Then figure out the problem from there. If the LED is not working, it could be some sort of power problem. Check the voltage going to the LED.
thanks i'll read through that page. this has got me pretty bummed out, but i'll figure it out. The pedal worked great since I built it in February... I'm going to go buy a tester tomorrow so hopefully this weekend I can get it working again. The LED was working last night, but now today, I'm getting nothing. I'm thinking its a power problem, but i'm not too sure what i'm really checking.
Quote from: StevenJM on June 08, 2012, 01:03:40 AM
Quote from: aron on June 08, 2012, 12:56:12 AM
I love the audio probe as described in the debugging page. I would "listen" to Q1's base, Q2's base, Q3's base. That will tell you what stage is not working. Then figure out the problem from there. If the LED is not working, it could be some sort of power problem. Check the voltage going to the LED.
thanks i'll read through that page. this has got me pretty bummed out, but i'll figure it out. The pedal worked great since I built it in February... I'm going to go buy a tester tomorrow so hopefully this weekend I can get it working again. The LED was working last night, but now today, I'm getting nothing. I'm thinking its a power problem, but i'm not too sure what i'm really checking.
Might be worth re-flowing all of your solder joints. Intermittent faults are the hardest to find.
With your DMM on resistance, there should be 0 ohms (or as close to as your meter will show) when measuring between both ends of your pot and switch wires.
You can also use this function to check that your bypass switch is working correctly (as in, you'll get a '0' reading between one set of contacts, and not the other - the vice versa).
Hope you get it sorted.
I don't think it's a soldering issue, but reflowing everything couldn't hurt. The most frustrating part is that it was working fine for so long, including that night. Then suddenly it just stops.
I'll get a tester after work today and trace the power circuit and see if I can find my problem in there. If not, I'll just keep looking and ask questions here.
Thanks for all the help so far everyone.
The Audio Probe has kept me from going nuts more than once!
http://www.diyguitarist.com/PDF_Files/DIY-AudioTester.pdf
Are you running it with a battery now? Could it be that the power supply is damaged? I dunno... I'm kind of a dummy with this stuff.
I tried both ... battery and 9v adapter. Same results. I'm gonna have to read through that audio probe idea again, I got a little lost reading through it.
What sound am I looking for when I'm touching parts? Just a buzz?
Quote from: StevenJM on June 09, 2012, 05:43:29 PM
I tried both ... battery and 9v adapter. Same results. I'm gonna have to read through that audio probe idea again, I got a little lost reading through it.
What sound am I looking for when I'm touching parts? Just a buzz?
The audio probe allows you to 'listen' to each stage in turn. Think of it as a 'circuit stethoscope'.
You should be able to find the point at which the audio signal is lost in your pedal - and then drill down to find out why.
The first couple of de-bugs are a PITA, but you *do* learn from them.
Hang in there.
if I buy a multimeter with the continuity tester, thats basically the same idea, right?
Not the same. The audio probe lets you tap in to the circuit and actually listen to the guitar signal through your amp at any point in the circuit's audio path.
I'm so confused by this issue. I got it so the light will turn on, but then fades away right away. I'll try a different battery.
I need to buy a capacitor so I can try the audio probe. None of my electrolytic caps look damaged... And I went thru the board with a continuity tester and it seemed like all my parts were passing a signal. (it was kind of a pain using that thing)... Something is definitely screwing with me.
The thread's gone on too long without the most important things from the debug thread....the schematic, subs (if any) and voltages
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0
If you don't understand how to take them (multimeter required), someone will help
I have off tomorrow, I'm going to menards first thing in the morning and getting a multimeter. Ill probably have a handful of questions on using it... I've used one to read ohms of a speaker and guitar parts but never a circuit board. I was hoping this would be an easy swap of a part and it'd be working... But I'm kind of glad it didnt fix it just so I can learn how to do the troubleshooting.
Quote from: StevenJM on June 10, 2012, 10:36:10 PM
I was hoping this would be an easy swap of a part and it'd be working...
It probably will be, but multimeters and audio probes pinpoint
I should add that an audio probe is only good if you know how to follow the signal path on a schematic and translate that to a real world circuit. If you can't do that, it's not going to be much help...
First off... the LED issue was due to a battery issue, so i grabbed a different battery and the LED works fine now.
Schematic:
http://www.generalguitargadgets.com/pdf/ggg_secf_sc_bst.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
The battery reads out at 9.04v so its a fresh battery... these are the results I got...
Q1
C=8.93
B=0.01
E=0.00
Q2
C=3.41
B=0.60
E=0.00
Q3
C=6.03
B=0.71
E=0.12
D1
A=0.00
K=9.19
Anything funny stand out to ya guys?
the led should've lit with a dead battery...you only need 2-3v, i believe...
if you checked out the build instructions on the GGG site
http://www.generalguitargadgets.com/projects/73-fuzz-tones/89-shin-ei-companion-fuzz
"Shin Ei Companion Fuzz Build Instructions"
...then, you can see Q1C is the most off. your collector is near the supply voltage (9v), which it should not be. i'd check components around that area first
from ggg:
===
Component Location Voltage
9 volt power supply 8.8v
Q1 Collector 6.6v
Base 0.6v
Emitter 0v
Q2 Collector 2.0v
Base 0.6v
Emitter 0v
Q3 Collector 6.6v
Base 0.7v
Emitter 0.1v
===
the fact that you have 6v on Q3C and the output comes right off that leads me to believe you should be getting some sound. what do you get now?
did you check the 10uf at the output?
Quote from: LucifersTrip on June 11, 2012, 06:10:28 PM
the led should've lit with a dead battery...you only need 2-3v, i believe...
if you checked out the build instructions on the GGG site
http://www.generalguitargadgets.com/projects/73-fuzz-tones/89-shin-ei-companion-fuzz
"Shin Ei Companion Fuzz Build Instructions"
...then, you can see Q1C is the most off. your collector is near the supply voltage (9v), which it should not be. i'd check components around that area first
from ggg:
===
Component Location Voltage
9 volt power supply 8.8v
Q1 Collector 6.6v
Base 0.6v
Emitter 0v
Q2 Collector 2.0v
Base 0.6v
Emitter 0v
Q3 Collector 6.6v
Base 0.7v
Emitter 0.1v
===
the fact that you have 6v on Q3C and the output comes right off that leads me to believe you should be getting some sound. what do you get now?
did you check the 10uf at the output?
The last battery had some damage to the negative snap, so the battery clip wasn't sitting in snug, resulting in the LED issue...
I'm not sure why that Transistor is running so high.
I tested the last 10uf cap, right before the output of the board and thats giving me a 6.08v reading too, the same as the C of Q3.
My 22K resistor before Q1 doesn't really seem to be resisting much power. The reading on one end is 8.98 and the other end (leading to Q1) is 8.70.
But still, now i'm questioning if its something off-board thats my issue. all my wiring LOOKS fine... and the pedal was working fine for months, and minutes before it stopped working.
I feel like i'm close, but i also feel like throwing this thing against a brick wall.
So i made a little audio probe... and i get sound all the way up to the base of Q1, but anywhere I go from there i just get a shock-like noise but no sound. But I also get a huge volume drop going from one side of the .047uf to the other side of the cap, right after the input. Is that normal?
from the audio probe & voltage info, I would start by replacing Q1
q1 and q2 i think might need to be replaced...
I'm not sure whats different now compared to a few hours ago... but now i'm getting even more ridiculous numbers for Q2.
But this is what i'm getting while typing this...
Q2 (GGG's readings in parenthesis)
C=7.66 (2.0)
B=3.74 (0.6)
E=0.00 (0.0)
I've been unsoldering/resoldering everything trying to get this thing to work and nothing... theres only so many parts to this thing, it shouldn't be this much trouble.
out of frustration i decided to put in new transistors just now. I had some spare 2N3904 so I put them in place of the 2N2369s and this what I've got now...
Q1 (GGG)
C=2.43 (6.6)
B=0.58 (0.6)
E=0.0 (0.0)
Q2 (GGG)
C=0.84(2.0)
B=0.54 (0.6)
E=0.0 (0.0)
So the numbers are still off, but now lower instead of higher than GGG's recommended readings... but I just plugged it in, and I've got fuzz again. So i'm pretty relieved... i can go to bed now haha...
Hopefully the 2N3904s doesn't change the beast this fuzz was before it stopped working. I used the 2n3904s in a fuzz rite clone a while back and liked the results so hopefully the same will apply here.
Thanks for everyone's help... i would've had no clue where to even start if it wasn't for the help here.
Any other input on the numbers being off? or is that normal for the type of transistor i have in there now?
So it seems to go back to what I suggested early on, that one or more the active components got damaged from an accidental reversal of the power supply polarity. That's not supposed to happen if there is a reverse polarity protection diode on the power supply of the circuit. Did you put that diode in your build StevenJM? Just curious...
I do have the diode in my circuit...
That's just weird. Seems like something that should have never happened. :icon_confused:
Quote from: StevenJM on June 12, 2012, 01:43:46 AM
Q1 (GGG)
C=2.43 (6.6)
B=0.58 (0.6)
E=0.0 (0.0)
Q2 (GGG)
C=0.84(2.0)
B=0.54 (0.6)
E=0.0 (0.0)
So the numbers are still off, but now lower instead of higher than GGG's recommended readings... but I just plugged it in, and I've got fuzz again. So i'm pretty relieved... i can go to bed now haha...
Any other input on the numbers being off? or is that normal for the type of transistor i have in there now?
you see how the voltages pinpointed the problem area...
different transistors have different gains, so you should expect some change in the voltages when you swap. you can adjust Q2's collector voltage by altering R4 if you'd like to see if it makes a change to the tone....a 50-100K pot there will work well.
I guess I should've known where the problem was when my audio probe stopped making sound... I just thought I was doing it wrong rather than the part not working.
I'm just glad I got it figured out. I might play around with that R4 resistor... How would I go about hooking a pot up to that though? That might be cool to play around with.
Quote from: StevenJM on June 13, 2012, 02:18:37 PM
I might play around with that R4 resistor... How would I go about hooking a pot up to that though? That might be cool to play around with.
I just checked and I actually have a permanent external pot there on mine. just hook the middle lug and either of the other two to the same points where the resistor is.