wah pedal doesnt make sound!

[lerxst88]

this is just when the effect is engaged. i went thru the whole pedal and multimetered EVERYTHING except the battery itself. maybe some can make sense of these readings. unfortunately i dont have a nice new digital multimeter but i have an old one i found in our basement so please bear with me. if these readings suck i can ask my girlfriends mom to borrow her fancy one.



Terminals
1. 0
2. 2
3. 2.5
4. 9
5. 1

R1
R 0
L 0

R2
R slight waver
L slight waver

R3
R 1
L 9

R4
R 1.5
L 1.5

R5
R 1
L 0

R6
R slight waver
L 0.5

R7

R slight waver
L 0.25

R8
R 2
L 1

R9
R 9
L 7

R10
R 1
L 7

R11
1 1.5
2 1.5
3 1.5

C1
R 0
L 0

C2
R 7
L 0

C3
R 1
L slight waver

C4
R 0
L 1

C5
R 0.5
L 1

T1
R 0
L 0.5

Q1
C 7
B 0
E 7

Q2
C slight waver
B slight waver
E 1.5

J1
purple 1.5
black 1

J2
T 0
R short
S 2

Switch
green 0
blue 2

[John Lyons]

Unfortunetly we have no idea what you are talking about when you mention colors, resistors and "terminals".
What schematic are you using?
Read the debugging thread and let us know what the voltages are on the transistors.

john

[lerxst88]

derr! i forgot the picture



im not sure how to check for what voltage the transistors but theyre mpsa18's i took out of the crybaby. so is the inductor

[lerxst88]

Q1 and Q2 are both transistors i just measured everything so i didnt leave anything out

the colors are the wires that are connected to the part indicated (switch, green means the connection between the switch and the green wire shown in the schematic has X voltage)

as for the resistors, caps, and inductor i wasnt sure how to take volt readings so i took a reading from the right side (R) first and then one from the left (L) side.

the terminals are the 1 2 3 4 5 points on the board. i call them terminals because they are the ends of the board and its simplest to just wire the board up from these points. what is the correct term?

also i wasnt to mention some parts are reused from the old crybaby. specifically they are: the inductor (2 contacts not 4) (one contact was pulled out during extraction but i pushed it back in.) the transistors (both mpsa18's), pot, switch, battery clip and the wiring harness for the switch and pot.

any help that gets this thing working or makes me a better DIYer will be greatly appreciated!!!

[Paul Marossy]

Build an audio probe: http://www.diyguitarist.com/PDF_Files/DIY-AudioTester.pdf
Feed your wah a signal from an audio oscillator, function generator or a keyboard that can have infinite sustain.
Check the audio path from the beginning of the circuit
Where your signal stops is where your problem is.

Verify that the circuit is getting power and make sure that the switch is wired correctly. You'll need a multi-meter of continuity checker to verify that the circuit is getting power.

[Paul Marossy]

the inductor (2 contacts not 4) (one contact was pulled out during extraction but i pushed it back in.)

BTW, if you pulled out one of those pins from the inductor, there's a 99% chance that you broke the tiny wire from the inductor winding connected to that pin. And, if you didn't connect that tiny wire back to that pin, then your wah won't make any wah-like sounds because the inductor can't do its job in the circuit.

Just something I thought of after coming back to this topic. I thought I'd mention it so when you get it working, it won't drive you crazy because it doesn't sound like a wah pedal. 

[zombiwoof]

One other thing to check, another poster here had a similar problem, it turned out to be a broken connection inside the battery snap.  Check out the snap for continuity, and replace it if needed.

Al

[lerxst88]

Build an audio probe: http://www.diyguitarist.com/PDF_Files/DIY-AudioTester.pdf
Feed your wah a signal from an audio oscillator, function generator or a keyboard that can have infinite sustain.
Check the audio path from the beginning of the circuit
Where your signal stops is where your problem is.

Verify that the circuit is getting power and make sure that the switch is wired correctly. You'll need a multi-meter of continuity checker to verify that the circuit is getting power.

alright i think ill try this. you plug the keyboard into the input and the audio tester goes to the amp right? also does the effect need to be on or off? and what uF is the capacitor?
i think ill end up getting a new inductor since i broke the old one. what would be a good (but relatively cheap) way to go for that? i heard you can use an audio transformer from radio shack

thanks!

[Paul Marossy]

alright i think ill try this. you plug the keyboard into the input and the audio tester goes to the amp right? also does the effect need to be on or off? and what uF is the capacitor?
i think ill end up getting a new inductor since i broke the old one. what would be a good (but relatively cheap) way to go for that? i heard you can use an audio transformer from radio shack

thanks!

Yes, signal from keyboard to your circuit, which is ON. Output of audio tester to amp. You can use a 0.1uF cap.

You will have to get a new inductor (if it's really broken) unless you can fix your inductor. I have fixed one before, it's a bit tricky, but not impossible. You can usually get cheap Dunlop wah inductors off of ebay. Don't have any personal experience with the RadioShack audio transformers....

[lerxst88]

i might as well try to fix the inductor because its not gonna fix itself if its really broken right? any advice?

[Paul Marossy]

i might as well try to fix the inductor because its not gonna fix itself if its really broken right? any advice?

Just scrape the lacquer off the end of the broken wire and solder it back to the post that it's supposed to be connected to. The only thing hard about it is that it is a very thin wire to try and solder.