Trouble with Orange Squeezer build

[forbin80]

Hi All,

I need help with the orange squeezer project from GGG (and from tonepad, for that matter).  This is my first attempt at a stompbox, and having a decent amount of electronic experience with building computers, installing car stereos, making thermal fan control circuits for computers, I thought this would be a piece of cake.  It has been very humbling.  

I etched the board for the GGG project (backwards - I know - "noobs") and had to flip my IC (so glad I put a socket in!) and transistors, but couldn't get it to work.  Then today I took apart the GGG one and built the tonepad version of this effect on Radio shack PCB (and with new JFETS and opamp).  It looks a hell of a lot cleaner and nicer but I get the same problem: true bypass works, but with the effect on, all I can get is some low volume staticy popping when I pluck strings.  Almost like it's trying to do its job but very little is getting through.

Here's the facts/substitutions:
It will be enclosed in a Starfish Tuna can (I am on a LOW budget)
I'm using MPF201s for the transistors
I'm using an NE5532 opamp
I didn't have a 390k resistor so I twisted up a 330k and a 56k in series
I'm using a cheap (but brand new) flip switch DPDT from radio shack (this box is for home use and will probably stay on most of the time, so I saved money on the stompswitch.)
I'm using the inexpensive open panel-mount stereo (input) and mono (output) phone jacks from Radio Shack
Here's probably the biggest deviation: the 2,200 pF capacitor was not at radio shack, so I got the next smallest film capacitor: .01 uF.  I realize this has like 5 times the capacitance but I figured it would at least be ok to get it working and I could change it later next time I ordered some stuff from mouser.  However, I really don't know what bearing this has on the circuit.  This could be the reason it's not working.
Also I'm using 22 gauge solid wire if that matters at all (I'm very careful about nicking wire when stripping)

Even in true bypass mode I get a lot of buzz (in or out of the tuna can).   I don't know if that's because I'm using cheap phone jacks or what.  

Like I said, I am BRAND SPANKING new to this so any help would be appreciated.

Oh the other thing is all I have is a 40 watt radio shack soldering iron.  I've seen a lot of recommendations for a lot less wattage, so I'm wondering if I'm damaging the components with this thing.

Meanwhile I will be trying some of the troubleshooting tips I've seen in here and other sites, but I figured I'd see if any of these problems rang a bell for anyone.

Thank you!
Whit

[petemoore]

I'd consider a RACO box, much sturdier, you'll need to secure the punchouts with JB weld before drilling holes.
 You say buzz in bypass, are the jacks grounded?
 If you're soldering in active components, yes heat damage is a possibility, I soldered in opamps before and fried them...before I knew to use sockets.
 http://www.diystompboxes.com/pedals/debug.html
 Take pin voltages of the opamp and post them here.

[forbin80]

Thank you.  I will check those pinout voltages and post in a little while.  I know this is probably going to sounds stupid, but I have to ask.  I have all my components attached to ground on the circuitboard and all, but does that have to be attached to something, like the enclosure or something grounded?  

Also for checking the pinouts:  I have it set up so the battery isn't connected to ground until you insert an input cord from the guitar.  Do I just need to insert a cord to check these voltages or do I need to hook everything up (amp and all) and turn it on?

Oh also, I luckily used a socket for the IC, so I shouldn't have any heat damage there, but I did solder the transistors right in.  

Thanks,
Whit

[forbin80]

Ok here are the pin readings.  I may have done them wrong, but the only way I got numbers that seemed to make any sense was measuring AC w/ the whole thing plugged in and the amp turned on.

1 - .34
2 - .34
3 - .009
4 - .009
5 - .03
6 - .937
7 - .93
8 - 1.47

Thanks,
Whit

[R.G.]

That's not a valid way to tell the pin voltages.

You need to have the input cord plugged in to supply power to the circuit, and a good thing is to have this plugged to your guitar but the volume pot turned all the way down. The amp is completely unnecessary; the cord to the amp doesn't need to be plugged in (if your power switch is on the input jack).

You need to set your meter to *DC* and connect the black lead to the signal ground on the circuit.

I have all my components attached to ground on the circuitboard and all, but does that have to be attached to something, like the enclosure or something grounded?

For proper operation and RF shielding, there needs to be one connection from circuit signal ground on the circuit board to the effect enclosure. This is usually done with a ground wire from the circuit board ground to the ground lug of either the input or output jack. You can check whether this is being done by using your meter in ohmmeter mode, 100 ohms  range, between the circuit board ground and the ground ring of the input jack. Should show 0 ohms.

[forbin80]

Thank you, I had a feeling I wasn't doing that right.  I didn't think I should be using AC.  So should the values be really low?  Like in the mV range?

As far as grounding goes, when the input and output jacks are in the enclosure, they're fastened to the enclosure and the wire from the ground on the circuit board is fastened to the gound lug.  On input, the battery ground is fastened to the sleeve.  It may be the other way around (battery gnd -> input gnd lug and circuit gnd -> input sleeve), but wouldn't this create the same effect?

I will post the correct voltages in a little while.

Thanks!

[R.G.]

So should the values be really low? Like in the mV range?

They should be volts and perhaps tenths of volts.

It may be the other way around (battery gnd -> input gnd lug and circuit gnd -> input sleeve), but wouldn't this create the same effect?

When the cord is plugged in, yes, but you'll get hum when it's pulled out. You really need to signal ground the sleeve and open the battery (-).

[forbin80]

Wow I feel like an idiot, but something's not right here.

Should I be attaching the negative terminal to ground and using the positive to take the measurements?

[forbin80]

ok does this look right:


1 - 8.14
2 - 8.14
3 - 8.55
4 - 8.55
5 - 8.20
6 - 8.12
7 - 8.07
8 - 8.18

[forbin80]

I can't even duplicate those numbers now.  I believe i had black connected to the lug that the battery- was connected to, but I can't get it to do that again.  Pretty much everthing gives me ones or tenths of millivolts, so I'm assuming that basically means no voltage.

[R.G.]

Should I be attaching the negative terminal to ground and using the positive to take the measurements?

Yes.

1 - 8.14
2 - 8.14
3 - 8.55
4 - 8.55
5 - 8.20
6 - 8.12
7 - 8.07
8 - 8.18

That is a set of measurements that both look like it was measured OK, and that indicates a problem with the circuit.

We'll go through them sequentially.

The first one to solve is - how come the power to the chip is not good?
You should have 0V on pin 4 and whatever your battery voltage is on pin 8 if you used a dual opamp.

[forbin80]

Thanks. I found a spot in the layout where I failed to make a link, but even after fixing it it didn't work.  It looked relatively non-crucial in the schematic.  I have not had a chance to take voltage readings and probably won't get the time until tomorrow, but I will post them as soon as I can.  

One plus is that turning the volume knob on the effect finally does something!  It make the low static higher volume. :roll:

Thanks again for your help, this has become an excellent learning experience.

[R.G.]

No problem - just yell when you get more.

[forbin80]

Yes!  I got it working.  As it turns out, there were two places on the layout where I forgot to connect component leads.  They were small gaps so I didn't notice them when I was checking the layout.  Good to know I'm not crazy, just careless and sloppy.  Anyway, it sounds great, just what I was expecting (never actually heard an Orange Squeezer).  I did take readings and they all matched up with those from the GGG build (I didn't realize till last night that the bottom of the build instructions had pinout readings) except for pins 1 and 2 (which will be the same b/c they are connected.  Mine read something like 4.5 and GGG has like 8.5 or something.  I don't know if it's b/c I'm using the tonepad layout and it's different or something, but it sounds ok so I'm not worrying about it at the moment.  

I did fiddle w/ the bias trimmer and noticed how one end I shut the pedal down and the other end I get overdrive, that is really cool (sorry - first pedal so I'm excited).

Thanks for your help, my next project is converting an old bogen tube amp for guitar.  If anyone knows any good resources for this they'd be much appreciated.

Thanks again!
Whit