My effect works for about a minute then quits....

[mikestahlme]

My effect works for about a minute then fades out. After waiting a while (45 min.?) It works again, then fails again.

I'm building a bluesbreaker clone from General Guitar Gadgets. With mods to turn it into an Analogman King Of Tone.

Here's the GGG's Bluesbreaker info: http://www.generalguitargadgets.com/projects/17-distortion/106-bluesbreaker

And the mods to turn it into a KOT: (click on the picture)
http://revolutiondeux.blogspot.com/2008/05/analoggirl-king-of-turds-overdrive.html?showComment=1333675054872#c29877562548777292

I'm using a JRC4590D instead of GGG's TL072

I'm also using a regular 50KB pot instead of a 50KB trimpot.

[timd]

I'm prototyping a new pedal - which I'll share when done - and it performed really well on the breadboard. When I wired up a pemanent version, it killed somewhere from 5 seconds to about 20 seconds in. My fix was to experiment with small resistors (100 ohm and smaller) between the 9V positive and the circuit board. Might be worth a try...

[CodeMonk]

First thing I would check...
Right after it stops working, check to see if any of the components are hot.
Particularly Electrolytic caps, IC's, and transistors.

Might want to check while its working as well.

If something is getting hot, check things like, solder bridges, components attached to the hot component, your power source, among other things.

[mikestahlme]

Thanks, I don't have the time or small enough resistors at the moment to experiment with that. So until then...

I tested it again and felt for warm/hot components both while it was working and when it quit. Nothing. I felt it with my fingers and my upper lip (thinking that would be more sensitive to changes in temprature) nothing felt hot or even warm.

[amptramp]

My first suspicion would be the electrolytic capacitors because they are the flakiest part of any design.  You have one across the input power rail and another on the Vcc/2 half voltage supply.  There is also one on the output, but a failure there would just change the tone, not kill the sound.

[mikestahlme]

I replaced the 1uF elect. cap near the output with a 1uF tantalum cap. The electrolytic cap was from a different board and I may have overheated it when I pulled it off. I don't know for sure.

I checked my solder joints and tried to fix whatever ones looked cold. For some reason the solder I'm using doesn't usually stay shiny when it cools so sometimes it's hard to tell.

After testing it again I found that I don't have any problems until I turn the gain pot up all the way or when I flip the switch that turns the added diodes on and off. (top right on the picture of the modded pcb)

I'm still a noob at this as this is only my second project.
The first was a Devi Ever US Fuzz, which was extremely simple.

[mikestahlme]

Also, when I flip the switch mentioned above I get a very gated sound, only quiet signals pass through. The effect is staying on, but when I play around with the switches and gain knob it eventually quits

[Jdansti]

You may have already done this, but  check your PS voltage before you power it up, and then check it again after you power it up. Take your first reading after powering it up where the power connects to the board and before you do what ever it is that you think is causing it to die. Then while you have the meter connected at the same location tweek the controls that cause it to fail and see if the voltage changes.

I just wonder if you either have a PS problem or if something in the circuit is overloading the PS causing it to shut down. If you are using a battery, see if the battery gets warm.  

Also, make sure that the board is not resting on anything conductive and you aren't using one of those clippy holders to hold the board up. Once I was testing a board and had it secured to one of those clippy holders and didn't realize that I was shorting the power. The 9v battery got pretty warm before I figured out what the problem was.

As a last note, double check your power connections, especially if you have your bypass switch wired up.

[R.G.]

 As a general debugging tip, when something either won't work at all or stops working, it's either (1) a dc condition that forces it into non-working, or (2) an oscillation that is keeping its mind occupied with things other than your signal.

This is why the debugging process listed in "Debugging: what to do when it doesn't work" is so deadly effective. It forces your mind away from preconceived notions about what it should be doing (and frankly, the circuit could not care less what you think it should be doing) and into what it *is* doing. Comparing the actual results to a more generic understanding of how electronic devices do work generally nails the problem.

So: Get out your meter. If you don't have a meter, get one. They're under $10 regularly at many places. If that's too steep for you, give up on building electronics. That's not being snide, it's just a fact.

With your meter, set it up and then turn on the power, measure voltages as long as you can be sure it's still in the "working" phase. De-power, let it rest/cool off/whatever it does, then measure some more voltages. Repeat until you have all the voltages mentioned in the Debugging Thread.

Oh, yeah. Write them down as you go.  It does no good to know later that something was 8.3 and something else was 3.2V.

Now comes the easy(er) part. Power it up and measure all the voltages again, this time while it's gone off the cliff. Write them down as you go.

When you get done, compare. Something will be different. Tell us the voltages. Some of us can make really good guesses from that data. Without that data, we have to make guesses like "It's possessed." or "Oh, yeah. Your antimatter injection manifolds are destabilizing."

[Jdansti]

Without that data, we have to make guesses like "It's possessed." or "Oh, yeah. Your antimatter injection manifolds are destabilizing."

Good advice. Gotta check those dilithium crystals in the gaviscon tubes, Scotty. 

[pinkjimiphoton]

to me, it really sounds like a bad cap...it's building up a charge, and then shorting to ground. once the cap is discharged again, the effect is working.

i bet it's a filter cap...an electrolytic one. are you sure you don't have any in backwards? or a fine (look with glasses and a magnifying glass) speck of solder or something offering a short somewhere?

i had a tube amp on the bench years ago...when it heated up, it would crap out. i reflowed the whole oilboard, and it sounded better. still did the same thing tho when it got hot.
replaced all the electros. problem was gone.

don't know which one, but i suspect that's where you're gonna find your problem.

[mikestahlme]

Thanks so much to everyone for the advice, I really appreciate it.

To R.G.
My electronics knowledge is pretty basic so I'm very willing to learn. I'll be sure to share my results when I get it figured out.

[R.G.]

My electronics knowledge is pretty basic so I'm very willing to learn. I'll be sure to share my results when I get it figured out.

No problem. We'd like to help.

[mikestahlme]

1.What does it do, not do, and sound like?
First of all, I think I should mention that I bought all of my parts from china through ebay.
Second, the solder I'm using doesn't get very shiny at all when it cools. Does this mean it is old, defective, over heated? (I keep my iron at 550) should I re-solder everything with different solder?

WHAT IT DOES:

When I first tried it the only thing that worked was the volume knob.
After looking at it again, I realized:
1. I forgot to put the resistor before the LED. (probably because I was over excited and rushing because I wanted to play it so bad)
2. I had the SPDT switches hooked up using the two outer lugs with nothing on the middle lug. This made the switch totally useless.
3. I had the ground wires soldered to the tip on both I/O Jacks. (over excited again. ugh.)

After fixing these blunders it worked.
It sounded great, just how I hoped it would. There was some static but I thought it was because I had the back of the box opened and the pcb was hanging out. About 45 seconds later it was practically dead.  I only get a very quiet, but clean signal as long as the gain is turned all the way down.

I tried it again 45 minutes later - same thing. I did this several times. When I turn the gain knob after it quits I can hear a wooshing static like sound (what I'm guessing is the sweeper arm turning in the pot.) The gain knob does this every time after the pedal quits,... again, except when it's turned all the way down, then a much quieter clean signal is heard.

I double checked my solder joints and re-soldered the ones that looked bad.

After this it worked longer. It seemed to run fine without any static or popping sounds, until I started playing with one of the switches. Also when I turned up the gain all the way the sound cut out completely. I experimented with turning the gain all the way up then back down until the signal came back. When the signal returned it sounded exactly the same as it did before I turned the knob all the way up.

One switch works fine, switching from a clean boost/very light OD sound to more distortion, not louder, just more distortion.

The other switch made a gated sound when engaged, only allowing the decay of the notes to pass through. The longer I had it on the stronger the gate would be and even less of the decaying note would pass through. Soon it would quit.

Other times when I tested it I turned that switch back off to see if the effect would still sound the same. The effect would sound almost normal after flipping the switch back off. For a few seconds it would sound a little fuzzy like a fuzz/od, then it would start to sound more like it did before I started playing with the switch. The more I turned it on and off the more static and little popping sounds would be heard in the background when the switch was off. After playing with the switch too much, the static/popping sounds got louder and then the effect quit. There was no static/popping heard while the switch was on.

The last couple of times I tested it, the effect didn't even partially work.

The volume pot has always worked, volume increases as knob is turned up.

The toggle switches stopped working altogether.

The gain knob is just doing the same thing it's always done when the effect quits.
(A much quieter than bypassed signal passes through when it's turned down, no signal when turned up even slightly, but there is no clipping. Wooshing sound is the only thing heard when pot is turned.)

I can hear the tone knob and treble boost knobs working, the background static and the quiet clean signal changes accordingly as the knobs are turned.

2.Name of the circuit =  Marshall Bluesbreaker Clone (True Bypass)

3.Source of the circuit (URL of schematic or project) = 
http://www.generalguitargadgets.com/projects/17-distortion/106-bluesbreaker

4.Any modifications to the circuit?
Yes, modifications to turn it into an Analogman King Of Tone.
http://revolutiondeux.blogspot.com/2008/05/analoggirl-king-of-turds-overdrive.html
Click on the white piture with the schematic to see it bigger.

Added parts:
10k Gain stopper resistor between C4 and R3/Pin 2 on IC

50kB Treble boost Pot between R12 and C9. Using the left and center lugs (NOT a trimpot like the instructions for the mod say)

1uF Tantalum output cap in parallel? with C10 (Positive to middle lug on 100k vol pot, Negitive to R13)

2 1N914 GE Diodes I don't know the terminology, but you can see in the picture that they are connected in parallel with the cathodes pointing in opposite directions. I also don't understand why they are placed where they are. I am using a SPDT mini toggle switch instead of a DIP switch. The Diodes are both soldered to lug 1 and the wire going from the switch to the board is on the middle lug, 2.

2 SPDT Mini Toggle Switches. One mentioned above between the diodes and the board, and another between R10 and R11. When I turned on the former (I believe this is the "distortion mode" switch) the sound becomes gated, only allowing the decay of the note to be heard. Eventually after turning it off and on enough times, the effect quit.


Also, I plan on building two of these, housed in one BB size enclosure, powered by a single power supply. I have not hooked up a battery clip like the layout shows on GGG's site. Instead when I tested it with a battery I unsoldered the power jack and just soldered on a battery clip for temporary use.
I have NOT put together the second circuit yet. I plan on running them in series, from the output of this one into the input on the next. Then the signal would go to the output jack from there.


5.Any parts substitutions? Yes:
R2: Changed 4k7 to 27k
R3: Changed 3k3 to 33k
R7: Changed 4k7 to Jumper

C5: Changed 47uF Electrolytic to 100uF Electrolytic
C6: Changed .22uF Film to Jumper
C7: Changed .22uF Film to .1uF Film


6.Positive ground to negative ground conversion? No

7.Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage? =>   9.74V


Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:

Voltage at the circuit board end of the red battery lead = 9.57V
Voltage at the circuit board end of the black battery lead = 0V


Now, using the original schematic as a reference for which part is which (that is, which transistor is Q1, Q2, etc. and which IC is IC1, IC2, C1, and so on) measure and list the voltage on each pin of every transistor and IC. Just keep the black lead on ground, and touch the pointed end of the red probe to each one in turn. Report the voltages as follows:
No Transistors

IC1 (or U1)
P1: 4.33V
P2: 4.29V
P3: 2.15V
P4: 0V
P5: 4.21V
P6: 4.62V
P7: 4.29V
P8: 8.79V


D1   (Mislabled as D5 on pcb. It is connected to the + pad on the pcb)
A (anode, the non-band end) = 9.47V
K (cathode, the banded end) = 8.73V

D2
A = 3.64V
K = 3.32V

D3
A = 4.28V
K = 3.95V

D4
A = 3.31V
K = 4.26V

D5
A = 3.93V
K = 3.63V

Added Diodes
D1 (Top diode in picture of mods. Cathode on right, going to board)

A = 3.84V
K = 4.18V

D2 (Bottom diode in picture of mods. Cathode on left, going to switch)
A = 4.18V
K = 3.84V

No Zener diodes

[R.G.]

First of all, I think I should mention that I bought all of my parts from china through ebay.

Essentially all electronic parts on the planet are made in China, India, Taiwan or Malaysia, etc. Buying semiconductors through ebay is a great way to get counterfeit parts, though.

Second, the solder I'm using doesn't get very shiny at all when it cools. Does this mean it is old, defective, over heated? (I keep my iron at 550) should I re-solder everything with different solder?

You probably got lead free solder. Lead free solder is workable on a well-controlled manufacturing line where the temp/flux/heat times and conditions can be tweaked in and run consistently. It is in general a disaster for beginners hand-soldering parts. However, I would not suggest tearing it all down. Yet. In the future, use 63-37 tin-lead electronic solder with a rosin core unless you live in a place where the government forbids you to.

After fixing these blunders it worked.
It sounded great, just how I hoped it would. There was some static but I thought it was because I had the back of the box opened and the pcb was hanging out. About 45 seconds later it was practically dead.  I only get a very quiet, but clean signal as long as the gain is turned all the way down.

I tried it again 45 minutes later - same thing. I did this several times. When I turn the gain knob after it quits I can hear a wooshing static like sound (what I'm guessing is the sweeper arm turning in the pot.) The gain knob does this every time after the pedal quits,... again, except when it's turned all the way down, then a much quieter clean signal is heard.
I double checked my solder joints and re-soldered the ones that looked bad.
After this it worked longer. It seemed to run fine without any static or popping sounds, until I started playing with one of the switches. Also when I turned up the gain all the way the sound cut out completely. I experimented with turning the gain all the way up then back down until the signal came back. When the signal returned it sounded exactly the same as it did before I turned the knob all the way up.

I think you have a problem that is unfortunately outside the normal DC conditions fixes. I believe it's oscillating ultrasonically, perhaps with some damage to a part or two. This might be consistent with the observed symptoms.

It is possible that one of the 100uF caps is in bad shape. Hard to say. It doesn't show up in the DC conditions. The 1uF tantalum on the output is extraneous at the moment.

My best advice is to (at least temporarily) remove the mods and convert it back to the stock version on the PCB from GGG. Get that running. Then do the mods.

[mikestahlme]

Ok, thank you so much!

I just replaced the two 100uF electrolytic caps and it started working!

Then after working perfectly for at least two minutes..... it quit again.

I think lot of caps I bought are faulty.

[mikestahlme]

Ugh, still not working right, even with new caps. I can get the right sound if I leave the gain very low. It clips more when I play hard, but when I turn it past 10% it cuts out.... back to the schematic. maybe it's a component somewhere around the gain pot??

[R.G.]

The bigger question is: why is it killing 100uF caps?

Exactly how do you have the + and - leads stuffed in that PCB? Are you sure the polarity is right?

[mikestahlme]

I un-did all the mods except one: C5 is supposed to be a 47uF electrolytic, which I don't have at the moment, so I left in the 100uF.

Even after reverting back to the original project it still does the same thing.

The spot on the pcb where the electrolytic caps go is a circle, half striped, and the other half is blank with a + sign just outside the circle.
I put the long lead in the plus side and the short lead in the striped side.

The new electrolytic caps I put in came from radio shack.
again, it still quits after a couple minutes of playing.

[R.G.]

We're going to have to dig deeper. Get out your voltmeter and meter the voltage across the 100uF caps before and after it quits. Is it (a) the correct polarity and (b) smaller than the cap rating?