Obligatory First Build Issues... (Spirit Box)

[RowanB]

Hello everyone!

So I had a fun day building my first ever pedal and of course it isn't working.

I have double checked all component values and polarity where applicable, checked connection points for dry joints and bridges and tested resistors for faults with my multimeter. Also double checked wiring for 3PDT switch. All seems fine.

I didn't want to be that guy and come to the forums asking for help without checking everything I could think of and read online, but I'm at the end of what I think I can do with my limited knowledge. I'm hoping it's just a simple n00b mistake with the components I've chosen as I have noticed a few issues...

So just to quickly outline the situation:

• I'm getting no LED light (have tested, lights up with continuity test, also definitely correct polarity).
• I'm temporarily using a 3PDT toggle switch as my footswitches are delayed, but I don't think that would cause an issue? Tried both with a 3PDT daughter board and by wiring 'manually'.
• In the 'top' and 'middle' positions I get a loud buzz and hum, and in the 'bottom' position I get a quieter buzz and hum that gets louder when I touch the strings or whatever earthed bit on my guitar. No guitar signal at all that I can hear on any setting.
• I have noticed looking at pictures that some of my capacitors don't look like the capacitors that others are using, even though the values as far as I can tell should be ok (same farad value, voltage rating fine). I actually think this must be where I'm going wrong but I'm too inexperienced to know why exactly! I did notice there were polarity markings on the board and a few of the caps I used were not polarised so yeah...
• No signal comes through the pedal when switch is in off position or when there is no power connected.
• My B2K pot is annoyingly a different size to the others, but can be wiggled into the right position to go into the enclosure, so that shouldn't be an issue at all, just mentioning it as it looks weird visually.
• Soldering is a bit rough, but as I say I did check all joints and redo a few to be sure.

So where am I going wrong? Obvious mistake in the layout of components? Wrong type of capacitors? Mix of all of the above?

Any help massively appreciated!!

 

[Robert]

Most likely you're going to have two different issues of some sort....

The first thing to figure out is why you don't have sound when the pedal is bypassed.... You should have clean uneffected guitar signal regardless of anything going on with the PCB / power. This would have to be a wiring issue of some sort. Make sure your wires are connected to the correct lugs of the 1/4" jacks. I would guess that this is the most likely cause of this issue.

The second thing (after you manage to get a bypass signal) is to figure out why the LED isn't lighting... Measure the DC voltage on both ends of the 1N5817 diode, and on Pin 8 of one of the TL072 opamps.

 

[Nostradoomus]

What voltage are those tiny 10uf electro caps?

Also your ceramic disc caps in the 100N and 10n value spots...you sure about those values? Generally those would be film box caps not disk type.

I know you mentioned it but definitely be sure! Especially if you didn’t spot the polarity markings on the 1uf and 2u2 caps (if they are tantalum!)

 

[dlazzarini]

I can’t tell for sure but your jack wiring looks like it may be wrong. Output jack looks to be grounded wrong. Not 100 % sure though. And the 100n, 10n, 2.2u like nostrodoomus mentioned.

 

[Barry]

Are those switched jacks? Not familiar with that version, but pretty sure your in needs to be straight across from the tip, and I think your in is run to ground

 

[RowanB]

Thanks for all the replies everyone! Going to knuckle down with this later on today and will hopefully make some progress.

 

[RowanB]

Alright, so after some rewiring of the jacks I now have a clean signal going through when no power is connected, but only in one of the 'on' switch positions. Double checked the wiring on the switch and it looks fine, so maybe the switch is faulty... But for now I'll take a clean signal in one position.

I measured the voltage of the TL072 opamps across pins 1-8 and it read -4.32v on both. No idea if that's anywhere near what it should be...

Those little 10uf caps are 16v.

As for those questionable caps... I've included a close up of them here, no polarity on the tantalum like ones. The values marked on them seem to be correct, but maybe I'm missing something. Maybe it's just worth ordering a load of film box caps to replace them? I also have a Dark Rift delay to (attempt to) build if I can ever get this one working, and there are a few more of these non polarised type of caps that I have for that as well.


Again, thanks so much for all the help so far!

 

[fornio]

With power connected do you get any signal when you aren't in bypass? Also does your LED turn on? That would at least confirm power.

 

[dlazzarini]

Alright, so after some rewiring of the jacks I now have a clean signal going through when no power is connected, but only in one of the 'on' switch positions. Double checked the wiring on the switch and it looks fine, so maybe the switch is faulty... But for now I'll take a clean signal in one position.

I measured the voltage of the TL072 opamps across pins 1-8 and it read -4.32v on both. No idea if that's anywhere near what it should be...

Those little 10uf caps are 16v.

As for those questionable caps... I've included a close up of them here, no polarity on the tantalum like ones. The values marked on them seem to be correct, but maybe I'm missing something. Maybe it's just worth ordering a load of film box caps to replace them? I also have a Dark Rift delay to (attempt to) build if I can ever get this one working, and there are a few more of these non polarised type of caps that I have for that as well.


Again, thanks so much for all the help so far!

View attachment 5764

I believe the 2.2uF and the 1uF capacitors in the lower middle of the board are supposed to be polarized. Either electrolytic or tantalum. The caps that are installed look like mlcc’s. This may be entirely ok as I’m far from being an expert on this but that’s what stands out to me. You say you rewired your jacks so that should be ok now.