I made this thread http://www.madbeanpedals.com/forum/index.php?topic=1672.0 only to find there were some problems with my build.
(http://img30.imageshack.us/img30/1244/1003150x.jpg)
(http://img31.imageshack.us/img31/7064/1003148y.jpg)
LED: works
Bypass: works but noisy
Effected: oscillates similar to playing around with my Fuzz Factory/Zombii build's "stab" pot; no guitar signal
Jacob, I haven't gotten around to making a testing rig yet, but that is sitting on my list of things n' pedals to do this summer ;D
I really appreciate any help
The first thing I'd recommend is taking it out of the enclosure. If you have done it true bypass than remove the switching, but if it's buffered leave the switching in. Remember to make sure that both jacks are grounded to the circuit as well.
If it works right there, then you know the problem isn't with the board. If it still isn't working it will be easier to repair.
Jacob
These are kind of general troubleshooting tips but I figured I would mention them anyway...
Did you try it out with the back off of the enclosure? It looks like with the way you have it wired up, the back may be shorting against something on the board (I usually put 3m foam tape on the back of the boards to protect them from shorting). I know it's obvious but I figured I would throw it out there...
Also, make sure you have no solder bridges on the board (components soldered together that aren't supposed to be connected).
Triple check your wiring too!!
yes sir, I took of the back (and I had electrical tape there to prevent shorting). I suspect the input/output and switch may be shady b/c I've never soldered resistors to the switch like that before. Does anybody know what might cause oscillating in an overdrive...specifically this sunking?
It could be any number of things, however, most often it seems that it's either a power wire issue or a bad IC. Have you taken it out of the enclosure to work on it yet? Is the oscillation still there?
If so, I'll have to recommend you start going through all your parts and begin to double then triple check all the values and orientations. Even if you're a veteran pedal builder this is the first place you need to go about checking it. This is the first thing I do when something doesn't work.
If you haven't taken it out of the enclosure yet, I recommend you do so, then do the step above. Once that's done, triple check your offboard wiring. Don't assume you've got it right, check it a third time.
Once both of those things are done, I have some more ideas I can share with you. Here's what I need you to do:
1. Verify it's out of the enclosure, and let us know what kind of bypass you're using (I think from the pictures you've got a DPDT so probably it's buffered)
2. Verify all your parts are correct, and you've checked this multiple times, both for value and orientation.
3. Verify that your wiring and offboard parts are correct, and you've checked this multiple times.
4. Tell me EXACTLY what is written on the top of the 3 IC's.
If after that you're still not sure what to do, please let us know whether or not you have a multi meter and I'll get you to take some measurements.
Stick with this, we'll get you working. Trust me it's worth it.
Jacob
I'll have to wait until the weekend before going back into the "workshop"
doh! one problem I found so far was I forgot to ground the input jack...
That wouldn't necessarily be a problem. In the enclosure, the jack would have been grounded. Outside of the enclosure, you'd need to ground it.
Jacob
Ok, I'm a noob at measuring voltages on ICs (my DMM only has a 2V DCV setting, and they sometimes are fluctuating...but the pedal is oscillating) but here goes:
IC 1 (pin->voltage) TL072 CN
1 0
2 -3
3 0 to -4
4 7
5 9
6 0 to -3
7 0 to -3
8 -3
IC2 TL072 CN
1 0 to 4
2 0 to 4
3 1 to 4
4 1 to 4
5 12
6 1 to 3
7 1 to 4
8 1 to 4
IC3 MAX1044
1 5
2 0
3 8
4 12
5 2
6 0 to 2
7 0
8 18
bump ???
here's what it sounds like: http://www.filefreak.com/files/797910_dbv8n/sunking.mp3
btw the humming there is not from the mic/computer...it's from the pedal's bypass
I'm starting to wonder if my whole switch wiring/configuration is off...
Hmm...
Your voltages are all so far off that I'm not sure that your measuring correctly or listing the voltages for the proper pins.
For example pin 8 of IC3 should be close to 9v the same as your power source.
Find the data sheets and follow the pin outs for the pin numbers. When measuring place the red probe on the pin and the black probe on ground. Be careful not to touch two pins with the red probe when measuring or this will change your reading.
As far as your DMM, it sounds like you have one where you need to set the range for measurement. You need to pick the range. Pick the setting higher than 2VDC it may be 20VDC. If your using the 2VDC it wont read properly and some DMM's will just display a 1 that fluctuates around. I don't know if this is the case with yours. You need to get familiar with your model.
Josh
when I do the above, I'm only getting 0.02 from the 9v DC jack...
I'm putting the black probe on ground, red on power lug ??? . It's a radioshack dmm but measures resistance fine
Ok just to clarify...
You have you multimeter in the 20v setting and are placing the red probe on the 9v+ and the black on ground and your only getting .02? Is this on the board or DC jack?
bleh noob mistakes before. here's the real measurements:
IC 1 (pin->voltage) TL072 CN
1 4.44
2 4.44
3 3.4
4 0
5 4.4
6 4.4
7 4.6
8 8.8
IC2 TL072 CN
1 4.4
2 4.4
3 4.4
4 -8.6
5 4.4
6 4.4
7 4.4
8 16.05
IC3 MAX1044
1 8.8
2 4.39
3 0
4 -4.3
5 -8.6
6 4.2
7 6.5
8 8.87
The pins on IC3 are the farthest from specified on build docs, but not that far off...
If it isn't the ICs, then it's wiring on the switch/pots/other parts?
Your voltages look good. It may be time to build an audio probe and work your way through the schematic. The bypass should not be "hummin" like that so something is definitely up :o
Taking some nice pictures with everything out of the enclosure may help us track down if something is incorrect with the wiring as well. Usually something like this is an easier problem (if there is such a thing).
Josh
Here's my switch, which I think may be the source of the problem.
(http://img860.imageshack.us/img860/8454/1003151.jpg) (http://imageshack.us/photo/my-images/860/1003151.jpg/)
Also as far as the pot wiring goes...does it matter which set is gain 1 and which is gain 2? Something weird I did (which may be cause for problem) is I soldered one of the wires to the metal ring near the lugs here
(http://www.taydaelectronics.com/catalog/POT50KBDUAL.jpg)
But I was pretty sure that doing so is the same as making a connection with the lug
Yeah, your voltages look alright. I've not got a set of mine around to verify, but I don't see anything glaringly wrong.
As for your switch and wiring, yes it's probably likely there's a problem in your bypass or pot wiring. As mentioned, an audio probe would be a helpful tool right now. Essentially, you need to start at the beginning (or the end) of your circuit, and then trace through to locate the beginning of the problem. Once we've found that, then we know how to fix it because we've located at least the start of the problem.
Is that understandable?
Jacob
Ok, I bought parts for my audio probe and put it together. It's a mono jack...sleeve to ground of pcb, tip to .1uF film cap and used as probe
I was testing the input jack during bypass...and I was getting a fuzzy, arpeggiated decay signal. any ideas?
I tested the effected signal too and got oscillations even on the input jack. methinks the problem is wiring at the switch?
And for clarification: in the build docs, the dpdt lugs should connect vertically, correct?
You DPDT switch is the x-wing type right? If it's to be oriented correctly, there would be three lugs up and down, and two lugs side to side. the middle pair is the common lugs, and then each side pair would be where the switch flips to.
My recommendation at this point is to completely rewire at least your switch. Perhaps you should also check through your jack and pot wiring as well.
Jacob
well looks like Tayda Mammoth sold me bad [economy] jacks--the tips and sleeves weren't well isolated from each other...
well, that happens. So it is it working now?
Jacob
I replaced the economy jacks with normal ones I got from Mammoth a long time ago.
Now the hum is gone when the power supply is removed, it's back when the plug is inserted. I measured the resistance between ground and 9v and it is 100k--does this make sense ???
I'm at a lost--oscillation is still there and I don't have enough good jacks for a working audio probe.
edit: could a broken 1n39a be a possible source?
It would still function without the 1n34's, it would just be raspy with higher gain settings.
It still sounds like you have a wiring issue...
Can you take some pics of everything?
yeah I'll post some later.
I've broken 3 1n34as so far >:(
btw, doubt there's many wimin 'round these parts but happy mother's day
Hey, don't know if this is of any help but... the wiring to your board in the picture you posted above looks really sketchy... namely that red one thats 3 down from the top... it looks like it's touching other components after coming off of the solder pad... IDK, just thought I would point that out.
Quote from: jtn191 on May 07, 2011, 09:13:52 PM
I replaced the economy jacks with normal ones I got from Mammoth a long time ago.
Now the hum is gone when the power supply is removed, it's back when the plug is inserted. I measured the resistance between ground and 9v and it is 100k--does this make sense ???
I'm at a lost--oscillation is still there and I don't have enough good jacks for a working audio probe.
edit: could a broken 1n39a be a possible source?
No hum with battery, hum with PS. What PS are you using? This is pretty typical off the Boss type. Plus, they put out closer to 12-13v.
No, there is no battery clip, so no battery at all. Here is everything explained more clearly:
When bypassed there is what sounds like 60 Hz hum and some guitar signal
When effect is "on" (IE LED is on):
-hum is louder
When Gain:100% Tone:0 Volume: 0%...I get a clean signal, similar to that when bypassed
When tone is increased, I get a bit of what sounds like a filter sweep, then an incredible high pitched squeal/scream when increased--which increases in pitch
When Gain is reduced, it sounds like a helicopter or machine gun "on/off" pulse wave
high res pics:
(http://img199.imageshack.us/img199/9728/1003152b.jpg)
(http://img69.imageshack.us/img69/5985/1003153f.jpg)
(http://img833.imageshack.us/img833/9034/1003154g.jpg)
regarding parts/attempts:
-I replaced the faulty (?) mammoth economy jacks with standard ones
-I've broken 3 diodes--1n34as--and only have one intact on the board. They are incredibly sensitive when sliding into tight quarters
-The green electrolytic caps are mammoths "audio grade" cap. It's not so much that I thought they'd make much of a difference as "eh what the hell"
-I attempted to resolder/clean up some of the wires bangerang101 mentioned
Clip the excess wire from the top side of the pcb's gain pads--your photos look like they may be shorting? Also, you're melting the insulation from your hookup wire, especially around the switch connection on the 'bottom' of the pcb. I'd suggest quicker solder work on the wires or get some of the lovely teflon coated 22ga wire avail on ebay (it's the shit!)
Lastly, clip your component leads (resistor, capacitor, etc) a little tighter.
Quote from: maysink on May 12, 2011, 03:28:41 AMI'd suggest quicker solder work on the wires or get some of the lovely teflon coated 22ga wire avail on ebay (it's the shit!)
+10000000 8)