First DIY stompbox (Crunchbox) problems

[Marcelo]

Hi guys, how are you? I'm new at this forum, and i've never did my own homemade stompbox, so i decided to build a Mi Audio Crunchbox from scratch, i did everything as listed but it doesn't get any sound , i checked the connections and everything was fine, and the first LED was blinking sometimes but no sound is coming out, i need help because i don't know what to do (Sorry for my english, i'm brazilian), so can you can guys help me through this? I'm gonna post the images so you can see.

[nickbungus]

Hi Marcelo.

We've all been there.  Please read the following:

http://www.diystompboxes.com/pedals/debug.html

I'd make an audio probe, its a very handy tool and also gives yourself better understanding of your circuit and what each stage does.

Also, have a read of this, as when you post your problems, the clever people on this forum can really help you as long as you help them to understand the problem.

[Kipper4]

Go to the debugging thread and come back with more info please.
Voltages?
I've had a quick look and they layout seems ok.
Your lead dressing could use some improvement and soldering too. We have all been there.
Yes an audio pobe may serve you well too.
Rich

[antonis]

As Rich said, some soldering splices on the board - especially between IC's pins and around it - are quite "suspicious".. 
Maybe you'll have to clear them with a thin file (sharper or nail)...

P.S.
What's the purpose of the toggle switch..??
(it's not included in your layout..)

[duck_arse]

as my esteemed colleagues say Marcello, hello.

also, I think one of your leds (D2, D3) is backwards. it is not clearly shown on the layout, but they should be one flat up, one flat down, doesn't matter which.

and your leads. find another couple of colours of wire, it will make all things that follow in life easier. and those holes in the board are there for the wires to pass through, such that they will be terminated happilly, both electrical, and mechanical. speaking to which, your 9V wire on the dc socket to the D1 looks to be shorting to ground on your pcb. this is why we use the holes. and why we want your voltage readings.

there also seems to be a wire tail or something at the bottom of the IC, possibly bridging to ground, again. as said, run a knife between yr joints to make sure they don't short to each other, otherwise the smokes may appear.

[Kipper4]

Welcome to the forum Marcelo.
Haha Duck Arse. I just liked your post. You got 16 likes so far.

Feeling honoured to be called Estimeed by my learned friend.

[Marcelo]

Guys, thanks for all the support, i'll do the necessary for checking the circuit, and i forgot to mention, i didn't use 0.1uF capacitors in my stompbox, because my local electronic store said that it wasn't available, so i used ones with 0.47uF, is there any problems using this value?

[Cozybuilder]

C3 is the gain-stage coupling cap, 470nF there might give a little more bass response. C12 is a power filter cap, doubtful if you will hear any change there.

[Marcelo]

antonis The toggle switch is a DPDT switch i bought for testing it

[antonis]

C12 is not a problem - you may totally ommit it...
(although it should be a 100nF ceramic and much closer to pin8 because it's there for bypassing IC supply..)

C3 is in the feedback loop of the second amplifier (if I read the layout correct..) and has an influence on second stage high pass filter..(other than DC blocking between 2 stages..)
(actually you have narrowed the cut-off frequency by a factor of 4.7... You may raise R4 by the same factor (10K ->47k) but then you must raise also R5 (1M -> 4M7) and lower C6 (100pF -> 22pF...)

P.S.
I don't have any diagram so I'm just guessing for layout...


edit: Cozy is faster than me...!!!

[Marcelo]

Hey dudes, i've checked the connections, my problem was with the switch, it was not connected correctly, but there's one problem left, the distortion is fine, but it makes of lot of noise, what it can be?

[nickbungus]

Glad you are getting there.  It was only a few months ago I was in the same boat but you've definitely come to the right place!

I'd firstly make sure all solder joints and connections are fine.  I had a noisy distortion recently and it was just a bad solder joint on a transistor.

Also have a read of these thread http://www.diystompboxes.com/smfforum/index.php?topic=101538.0

[Marcelo]

I forgot to mention, it's making noise when i crank the gain up.

[graylensman]

I forgot to mention, it's making noise when i crank the gain up.

Can you be more specific about the noise? Is it white noise? Or does it sound like you're picking up radio stations? Are you using single-coil pickups, which tend to be noisier?

[Marcelo]

Well, the guitar is loaded with humbuckers, and the noise is showing when i turn up the gain.

[antonis]

I don't like your 470nF(*) Electrolytic Cap (C3)...
(try to find the original 100nF or any other close value of Non-Polarized cap..)

(*) I doubt that it's a 470nF - unless it has rated voltage MUCH higher than 16 to 25V...

[Cozybuilder]

I agree with Antonis- C3 and C12 are both suspect. Looking at size of the can, I would guess these to be more like 47uF, but could be 4u7. Also, be sure you get the polarity right if you are using electros in those locations. C12 is correct, not sure about C3. I would either remove C12 completely, or replace with a small value cap- anything from 100pF- 100nF, this is a power filter in parallel to 100uF.