"Little Angel" - Super Simple PT2399 Mini Chorus

[chuckd666]

I assume that cap is part of the 'separate vref' mod shown in that schematic. I'm sure either is fine - if you have trouble with 10uf I guess just replace it with 47uf.

Just had a look through the thread and this part is for the following: "Audio vref: R23/R24/C17 - suggested by merlinb as a way to reduce noise dumped into the older version's 5v vref supply by the PT2399"

Then someone said "Yeah, you're right C17 should be 47u according to the schematic. In this case it doesn't matter, either value will do the same job, with no effect on the sound."

I'm sure either will be ok.

[jfrabat]

Great, thanks!  Now I only need to figure out why it is not actually working...

[chuckd666]

I'd recommend following the troubleshooting thread and adding the necessary info like voltages on both ICs and photos etc.

[Perrow]

Great, thanks!  Now I only need to figure out why it is not actually working...

I have to say you made an excellent first post. Lots of information about your problem, even pointing out some info was missing and asking if we needed it, perfect.

No need to excuse your self for posting in this old thread, it's been revived lots of times. The thread started six years ago and while it was last alive this summer it's always nice to see it come alive 

Welcome to the community.

[Ben Lyman]

welcome. I am that guy that doesn't know much but always encourages people to post pics of their builds 
Maybe then someone can spot something, solder bridge, wrong component, etc.

If you think the signal is getting muted way down, double check the value of the 470K. A common mistake (for me) would be to accidentally put a 4M7 right there 

Good luck!
Ben

[jfrabat]

Hey, guys!  I followed the troubleshooting guise, and, indeed, it helped.  Well, sort off...  I found the problem; the PT was not getting any power because of a bad solder joint on the leg that goes to the 5V source. 

I am attaching some pics of my build, for reference, but keep in mind, this is all prior to everything posted in this post here.  Anyway, I re-soldered the joint, and also "fixed" some others that seemed to have a similar problem (visually, anyway).  I say "Fixed" because now I get almost all the battery voltage regardless of where I probe!  Even the ground is showing 9V!  I screwed up the soldering and somewhere there is a short...  But I could not find it.  So I said screw it, and will start over again.  Now, a couple of comments:

• I am using a TL082CP instead of the NE5532 sinply because here in Costa Rica I am having a hard time finding the 5532.  If this is not compatible (can't see why it would not, but then again, what do I know!?), I also got some MC1458P, TL072CP, LM386 and C4558C's laying around, so let me know if any of these is a better replacement
• As of now, only the battery is connected.  My intention is/was (not sure yet!) to get it working, then paint the case, then install the power supply
• Yes, I am THAT bad at soldering!  Feel free to point that out!  LOL! (I like to think the mechanical part is more my strong point, but it's kind of hard to show that here!)
• In my defense, this is my 3rd pedal EVER.  Both the first 2 are point to point (both overdrives)... This is also my first PCB done, so complete newb here!

Felipe

[stallik]

As you admit, you need some practice with soldering. The image is not clear enough for me to be 100% but I can see joints which have not been made and multiple shorts where solder has spread to the thin box surrounding the layout. There also appears to be some unmade connections
My suggestion would be to remove all of the excess solder and then re make each connection. Work slowly and use a big magnifying glass
Good luck

[EBK]

Yes, I am THAT bad at soldering!  Feel free to point that out!  LOL!

Check out this page to help diagnose where you are going wrong with your soldering.  It has lots of great pics, and it tells you how to repair different types of bad joints.
https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems

[jfrabat]

Thanks for the link, EBK. 

I decided to start fresh.  I will also make the holes smaller on the PCB.  I used a 1/32 bit, but I think I will move to a 1/64 bit, as I find the holes are a little too big for this purpose, and that makes getting a proper solder joint right more difficult.  I mai also get a soldering iron with a better tip; the one I have is a bit hard to work with!

As for solder bridges, before the "fix" I checked with the multimeter for continuity, and there was none, and except for the bad solder at the 2399 input, the rest of the voltages seemed OK.  After the fix, I could not find any solder bridges, but I am sure at least one is there, as the voltage was wrong at many places.

As for the OpAmp, is there any issues with the switch?

Felipe

[maiko]

to check for solder bridges or breaks i use a flashlight with the component side underneath and the traces facing towards me
i put the flash light opossite me on the component side.  so any bridges or breaks show up .

[bloxstompboxes]

Choosing the right drill bit will help with the soldering. One other thing would be to watch the tarnishing of the copper traces and pads. I might be color blind but I don't see any shiny copper on that board and that makes for difficult soldering. Half the battle is knowing your handicaps and that you do. Practice and you'll be Rockin' in no time!

[duck_arse]

the opamp - your TL082 is the lower noise spec version of the TL072, more or less. the opamp is not doing anything terribly special or critical, so the swap should cause no bothers. if you get oscillator tikkings, you might try the 072 or the MC1458.

[jfrabat]

Thanks for all the help, guys.  Being new to the site, I have to say you guys are a very positive group.  I like that! 

And yes, I do not have a lot of experience soldering, but in my 43 years of living (EXACTLY 43 years...  It's my B-Day today!), I have found out that practice does make a difference, so being as bull headed as I am, I will keep at it until I get it right (or at least working! LOL!)!

Couple of questions;

1. What solder wire gauge should I use?  I have 0.015" and 1.0mm at home, but the thin one (0.015") I feel is TOO thin (takes forever to get enough solder in the joint) and the thick one (1.0mm) I feel is TOO thick!  Both are 64/40, by the way...
2. I am getting a new soldering iron; the one I have is a cheap Chinese one, and I feel it's too hard to work with.  I have been doing some online research, and they say something with flat head is better to heat up both the pad and lead.  What do you guys think of the Weller WLC-100?  It does not have automatic temp control, but I know Weller is suppossed to be good, and it has a flat head (and it's available locally!  That's always an issue here unless you want to wait a while for it to arrive!).

[bloxstompboxes]

That iron should be fine. It's the one I have, I think. As for solder wire thickness. I find that .032" is about perfect for our through hole pedal designs.

[duck_arse]

yes, yes, never mind all that -

...... in my 43 years of living (EXACTLY 43 years...  It's my B-Day today!), .....

- will there be cake?

[manners] sorry, how rude of me: happy birthday, welcome to the forum, will there cake? [/manners]

[jfrabat]

yes, yes, never mind all that -

...... in my 43 years of living (EXACTLY 43 years...  It's my B-Day today!), .....

- will there be cake?

Of course!  And you are welcome to some!  It will be served at noon here in Costa Rica!

[anotherjim]

Even the ground is showing 9V!

Very easy mistake to make in the heat of troubleshooting is forget to plug a jack in the input - assuming you have the usual TRS jack ring to ground power switching. Then indeed, you will not have ground on the pcb.

The solder is shiny, just not flowing. Even with a narrow "pencil" point tip that I use, it's wet the tip with fresh solder, apply to joint at an angle that connects the tip to component wire and copper pad, then feed in solder (not too fast) until it flows into the joint. I find I can use a pencil tip for just about everything. If it needs more contact area, I just lay the tip so its flatter across the joint.
That really thin solder wire is tricky, it can push through the holes and cause hidden shorts. 1mm is good for general work.
If the tip ever gets loose in the barrel, an oxide layer will form which makes a heat insulator. As the metal expands and contracts, the tip will come loose, so make sure it's tight before switching it on. Take it out and polish off the oxide if necessary.

[jfrabat]

Well, at least the box is coming out nicely! 



Once the laser printer gets fixed, I will redo the PCB.  I also ordered one online as a plan B.  I WILL get this pedal working one way or the other!

[duck_arse]

jfrabat - your "angel" reminds me a little of [adult_content_!!] Tori Avano [/adult_content_!!]. view that content with extreme caution.

[jfrabat]

Well, new PCB is done.  I checked for continuity, and I have it everywhere it is suppossed to be, and there is none where there should not...  I had to scratch the PCB to break a non wanted bridge, and made a couple more just to be on the safe side.  Holes are also half the size of the previous try.  Enough for the components, but with less gap.  Now its soldering time.  I hope not to screw up again.