Audio probe

[kojjum]

Need to build myself a Audio probe to trace a nonworking OD-1. Does anybody have a DIY probe schem or a tip how to build one?

Have done a search but the only hits I'm getting referes to the use of a probe when troubleshooting a circuit. Can't find any links or hints where to find building instructions except for this: http://www.diystompboxes.com/pedals/debug.html

Glad for all tips I can get.

//jens

[dosmun]

http://www.geofex.com/FX_images/audioprb.gif

[Melanhead]

it's on the debugging page:

http://www.geofex.com/FX_images/audioprb.gif

It's simple, just a jack, a .1uf cap and some wire.

You still need to supply the pedal some type of signal and then you trace the signal until it stops ... I use a signal generator.

[Melanhead]

damn I'm to slow

[kojjum]

Thanks!

I'll build one and use my keyboard as soundsource. I built a OD-1 on Vero that just won't fire up properly.

//jens

[rogerinIowa]

I built mine into a broken and discarded bar-code reader wand. I use a little smokey 9 volt amp to hear the audio, and I use a portable cd player ( which I run into the input of the effect that I am testing)as the audio source. It works awesome and looks great!  I start at the input and test each component until the sound disappears... The only question is how did I get along with out it before?

Build it, You will love having a probe....

[kojjum]

I built one...found the problem in ten minutes
Awesone tool and yet so simple. I use my keyboard and let int play a drumloop.

Thanks!

//jens

[dannydowrong]

checked out diagram and have a question...

so you plug your stereo into the 1/4" jack and probe with the bare wire connected to the capacitor...but how do you get the signal to your amp via an alligator clip?  

how do you get the signal from the probing end of the wire to the output of the amp's speaker? just making sure so i dont zap anything. thanks.

DD

[rogerinIowa]

you plug a sound source ( a keyboard, output from stereo, tone generator etc) into the 1/4" input of the pedal being tested so that the pedal input has a constant feed of audio. One leg of the capacitor is the wire that you use to contace the traces and components on the circuit board. The other  end of the probe's cap is wired to the tip of a 1/4" mono jack ( I use an enclosed one in my probe because the bar code wand housing is metal). An  Alligator clip is wired to the other lug on the mono jack, and you clip that to ground.So you now have a mono jack all wired up as an audio probe. You then simply plug a guitar cable into your probe's 1/4" jack, and the other end of the cable goes to an amplifier. You should be able to hear your audio source thru the amp as you probe. If you start probing at the input jack of the effect when the music stops you have passed the bad part/found the problem etc.

[dannydowrong]

iowa rocks

[formerMember1]

i built an audio probe to find  a problem in my austin treble blaster.
the probe buzzes when i touch my tongue :shock: , just kidding, my finger to the cap but when i test the circuit nothing happens.
i think my problem isn't a cold solder joint, in fact i doubt it is that.

my problem is my pedal doesn't get any power. i checked continuity, wiring etc. There is no sound when the pedal is engaged, but there is sound when the pedal is bypassed.

The only thing i changed is a 3pdt instead of a dpdt. i didn't wire up a LED to it yet. i will in future when pedal works. (could that stop my power?)

it is positve grounded.
i emailed everyone on the planet but no one could solve it.
please help if you have an idea of what is the matter.
thanks

[KORGULL]

formerMember1 wrote:

it is positve grounded.

Double check that all polarized components (battery,electrolytic caps,diodes) have their +positive side connected toward ground.
It can be easy to slip-up and connect one of these parts the typical (negative to ground) way when doing pos. gnd circuits.
Also, if you haven't done so already, check out the debugging page(s).

[formerMember1]

Yeah i have polarity correct. I checked out every debuggging page on the planet. i can't use audio probe because pedal has no power.

Those green chicklet caps, are they polarized? i have two of them, one input and  one output cap.
I dont think they are polarized.

Thanks

[KORGULL]

Those green chicklet caps, are they polarized?

No they're not polarized.
Use a volt-meter to see how far into the circuit the power is reaching. That should help you find the trouble. I've debugged all my pedals so far using only the volt and continuity settings on my meter.
Sounds like a ground or power connection is not right.
Keep checking all the connections. Sometimes you can miss a mistake over and over for hours before you finally notice it.

[formerMember1]

i checked how far the voltage goes. it doesn't go far. i get 8.98V to the 3pdt switch. then nothing else in the circuit.  It seems like wiring problem but i followed aron's post for wiring exactly except i switched grounds becaus mine is pos ground.  I also left out the LED.
I will keep going over it but I don't see finding a problem anytime soon.

Only thing i think it could be is a bad capacitor or resistor.  Everything else is checked with continuity etc..

thanks
PS:the lug that the battery attaches to gets voltage, so does the empty lug below it on 3pdt switch. (the lug where a LED goes)
Even if i am not using an LED do I still have to run a ground wire from that lug to somewhere.(i have 2 lugs on switch not used)
the lug previous mentioned and a lug between jumper wire.
thanks again for the reply

[KORGULL]

Is the battery- only going to the switch?
If you get voltage on the switch, you should at least get a reading right at the point where power enters the board if the battery is hooked up to both the board and the switch.
//www.diystompboxes.com/sboxforum/viewtopic.php?t=970
Run battery- to the board then to the switch.
Yes the lug for the LED and the one between the jumper should be empty in this case.

[formerMember1]

Well i for some reason thought(i dont know why) that black was ground. i ran that to switch and red to input jack. i switched them around today. but still the same problem. i now have hot(black) going to input jack ring. and ground(red) going to switch.  My pedal is pnp.
I checked my polar caps they are correct.

I still get no sound though. Did i fry something by having wires reversed.
I emailed ARON and he said i should not have voltage going to switch.(i thought you were supposed to get V to switch)

Also when i switched battery wires i still get voltage to switch anyway.

thanks.

PS:i don't get voltage anywhere other then the 2 lugs on switch.

[aron]

No, not that voltage should not be going to the switch - you do need it for an LED, BUT I asked you to do that to simplify your debug session.

You have a short or an open connection somewhere if the circuit is not getting power.

Beside the power going to the switch, it must also go to the board....

[formerMember1]

oh  :oops: ok sorry i got it ya now. thanks.
i will check over circuit again.

[formerMember1]

Man sorry for bothering you guys so much. :oops:

I checked everything, i checked continuity, i checked switch continuity,
i checked the wiring diagram,etc...

How do i test to see if the capacitors or resistors are not bad. contiuity on my tuner doesn't go to that range.(i know it is rare if they are but just wondering)

PS: i have 2.2M pulldown resistors at input and output of effect.
(wire from switch to resistor to input cap...
output cap to wire to resitor to switch)       :?:

I checked for shorts or anything grounding out but can't find anything wrong. I can't find any cold solder joints.(should i reheat every joint to make sure?)

i have another terminal strip,
should i just buy new caps and desolder and start over.
(or should i keep going?)

ONE OTHER THING:
i have pedal temporarily wired up in a cardboard box(cut out same size as real box) becuase i thought i was going to have trouble.
is something groundin out because it is not hooked up to a metal pedal yet.

PS:i know it is hard for your guys to help me since you can't look at the pedal in person.  Do you think i should take it to an electronic surplus store for help or won't they be able to help :?:

thanks again