New Builder Help

[guitarclichehere]

Ok, so I'm very new to building and have been on sites such as, muzique.com, amz fx, guitar gadgets, ect. trying to learn about the basics.

I ended up ordering a pcb from amz, its the dual op amp multi purpose board. I chose the MXR microamp type distortion, this is the link to the schematic http://www.muzique.com/tech/op1.htm .
ordered all my parts even the optional ones, and breadboarded the creation (it worked, I added on my own diode clipping section with a purfboard added on with wires and it worked on the breadboard but it was not added into the pedal because i wanted to eliminate it in the trouble shooting process).



I then placed each part from the breadboard into the pcb and soldiered in it. I wired up my enclosure (sorry for the tangled mess, this is my very first pedal and IMO they could have made the 3pdt switch hole lower to be further from the in/output jacks but I guess thats what I get for buying predrilled.) and added in my pcb. I get signal through the pedal, I used  this link http://rudemechanicaloz.files.wordpress.com/2008/08/muff-bypass-diag.jpg to wire my 3pdt switch.

The only different connection I have is i ran my sleeve connection from my input and soldered it directly to the same ground wire running from the pcb ground connection to lug 2 of the 3pdt switch. As far as i know, this is kosher, right?

will post pictures in a moment

any and all help and advice would be appreciated

[guitarclichehere]

[guitarclichehere]

this is how i wired my switch




the schematic from link



PCB hookup instructions

[PRR]

Welcome.

> I get signal through the pedal

Maybe I missed it (in all the parentheticals) but.... what is it doing or not doing? 

[guitarclichehere]

Ah yes, very sorry. I guess i forgot to post the actual issue!

Well, I plugged it into my little demo amp, powering the pedal using a one spot 9v power supply and this is the only pedal hooked up.

Signal makes it through just fine with the pedal off but once the switch is hit, led lights up, and sound is gone.

I have not tried blasting the amp to see if the signal is just really quiet.

[GibsonGM]

All other things aside, and having checked each and every switch connection and shown them to be made properly, it might be time for you to make an AUDIO PROBE!   

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

If using the probe doesn't locate a problem, go to the page "Debugging: what to do when it doesn't work" at the top of the stompbox forum (this form we're in).   If you can get the info requested, that would really help!

[Kipper4]

You could also double check the voltages with a digital multi meter.
At least 3 voltage references are shown on the amz page.

[Govmnt_Lacky]

Any reason you used what looks like a Germanium diode for R10?

[guitarclichehere]

hey thanks gibson! that looks great.
ill be making one of those in my spare time very soon!

I have a cheap multi meter but I guess im not 100% how to use it.
"monkey see, monkey do" is where im at right now, but slowly learning.

how do i check the voltages?

also, the parts list had a germanium diode listed for R10, which is why I used it. I'm assuming that diode is part of the clipping portion of the circuit?

[Kipper4]

hey thanks gibson! that looks great.
ill be making one of those in my spare time very soon!

I have a cheap multi meter but I guess im not 100% how to use it.
"monkey see, monkey do" is where im at right now, but slowly learning.

how do i check the voltages?

also, the parts list had a germanium diode listed for R10, which is why I used it. I'm assuming that diode is part of the clipping portion of the circuit?

how do i check the voltages?
place the black probe on the ground wire.
place the red probe on the test spot  (node (junction) of R11/R12) ) this should be half the supply voltage ie 4.5V
Test the supply voltage too to ensure you have ~9v
then test all the op amp pins too? and report back.

edit;al this is explained in the test voltage picture on the Amz page you linked to earlier.
I hope this is helping

[PRR]

> reason you used what looks like a Germanium diode for R10?

The PCB supports many variations. Bear marked the holes as "R10". For *this* variant, he used a diode at "R10" instead of a resistor.

> see if the signal is just really quiet.

It is a Booster. If it is "quiet", that is a Fail, it has to be fixed.

___________________________
Voltages:

Set volt-meter to read 10 Volts (auto-ranging is fine, but if you can jam it into a 10V or 20V range, it will read faster).

Put black lead on to Ground. Clip-lead is best, because you need hands free.

For *this* circuit, let's find the voltage on the "+" side (non-"-" side) of the electrolytic caps. Many of the most popular errors will, in this circuit, be reflected onto these caps. This also postpones the hassle of looking-up the pin numbers/functions to figure out what the pin voltages are saying.

[antonis]

Why do I think that something is going wrong with the length on "naked" cables on 3PDT switch...
(especially with the white cables in No 4 joint..)

[guitarclichehere]

ehhhhhh, i guess number four joint does look a tad naked but everything else seems to be pretty clear from shorting things out.

ok so i saw on the amz link where he talks about testing the voltages on those spots and they all get the same volts he has listed except for Pin 3 on the IC, its reading at 0.75.

input voltage reads 9.4v

IC pins 1 and 2 read 4.8v

pin 3 reads 0.75v
pin 4 reads 0.0v
pin 5 reads 0.75v
pin 6 reads 0.11v
pin 7 reads 8.4v
pin 8 reads 9.0v

C8 9.0v
C7 4.3v
C1 4.4v
C2 0.75v
C5 4.7v

i hope i did all that right.

now does this mean that a resistor towards the start of the circuit is wrong?

[PRR]

> C2 0.75v

This is probably correct. In fact the 4.7V at C5 means that C2 "is" about 4.5V when you are not looking at it.

C2 and pin 3 connect to a 4.5V supply, but through a HUGE resistor (10Meg). With just the chip and a good C2, it will settle at 4.5V. But when you hang a meter on that point, the meter loads it down. The voltage is lower *while* the meter is looking at it.

However with the meter looking at the output of the chip you are getting ~~4.5V. This would only happen if the input was really 4.5V un-metered. So the DC conditions are reasonable (allowing for meter loading).

Bonus: we can compute that your meter's input impedance is about 1.9 Megs. That's a nice value. It would be nice to be higher, but even 10Meg and 22Meg meters will still load-down a 10Meg circuit.

With DC conditions apparently OK, I would look to switch wiring. Looks to me like solder has wet the wire but not so-much the lugs. If solder is only stuck to the tarnish on the lugs, connection is poor/none. In a big/thin joint like this, you want to put the iron on the big lump (the lug). When that melts solder, there will be enough heat in it to melt solder on the thin wire.

[guitarclichehere]

ok, so in laymans terms, the switch is the problem?

all the wires in the switch are solder through the lugs of the switch. most of them were bent around the lug prior to soldering.

but youre saying i should re solder the connects of the switch?

[guitarclichehere]

or are you saying use a different type of wire?

i just have solid hook up wire from jameco

[nate77]

What he's suggesting, I believe, is that it seems that you have a bad solder joint (suspect at best) at the switch. When you get signal in bypass then you have the true bypass portion of the curciut working well. Unfortunately, this leaves the entire circuit, switch and wiring section (which could be as simple as an incomplete ground path) as potential problem areas. The switch definitely looks like it needs some TLC, so start there and see if it works for you. The trick is to have a warmed up soldering iron ready to go at the appropriate temperature, some solder (with flux) handy, heat up the suspect joint(s) quickly (because switches can fail if overheated or heated too frequently), and as the current solder melts, add a touch of fresh solder to the joint and you should have a nice joint. If you have too much solder on there already, you'll need to remove some with a solder pump, or some decent solder removal braid. This is a good start, as well as the audio probe. The folks on here are very good at spotting problem areas if you post all relevant dmm readings. The audio probe will help you spot a problem area as you follow the signal through the circuit. If you are stumped using the probe, you can post your findings here an help will arrive shortly after, as long as you're detailed about your process and such. Good luck man and welcome.

[guitarclichehere]

Ah, ok!

well i figured it out this morning. When I was first setting up this project i had a hard time finding the pull down resistor the pcb calls for and that was the only item not included in the breadboard build of the pedal (which worked fine) because it wasnt needed.

I took the pedal to an audio friend of mine (last resort, im trying to force myself to learn and not just lean on others knowledge but i have other projects that cannot wait)
and after I told him about the pull down resistor, he looked and noticed i had used the wrong resistor.

I didnt notice it called for a 22M resistor, I used a 22 ohm resistor. We replaced it with a much bigger resistor and boom goes that dynamite!

thanks for all the help you guys!
cant wait to start the next build!