SOLVED cetus preamp - no signal when engaged

[maertz13]

Hey all, first post, first build. i've done some much simpler circuits and mods, but this is the first big one.

i have good bypass, but as soon as i turn on the pedal, it mutes. LED comes on. volume is up. cables are good. i have reflowed every connection, checked the orientation of every polarized part, swapped the jacks around to ensure i am plugging in correctly, and at this point i am out of my depth. the only suspicions i have are that i have a bad component somewhere (i've read that there are bad batches of op amps), or that there is an error in the build doc that i'm unaware of. i found a picture of someone else's build and they've got the zener diode at D2 flipped. a backwards diode would certainly stop a signal dead in it's tracks.

i'm open to any ideas and any criticism at this point. i know my soldering is a little sloppy. reflowing a couple dozen components in a magnifying glass has made a flux mess. bad vision, shaky hands. there's a reason i don't do this for a living . also attached is a picture of the (much cleaner) build that was being sold on reverb (so it's safe to say it works) with that diode flipped

 

[Dirty_Boogie]

Not sure if this is the main culprit, but looks like you have these 220p and 2n2 caps switched:



Also, you’ve soldered your ICs directly to the board instead of socketing them - looking at the amount of solder used (on the top side of the board - no idea what the underside looks like) you might have fried one of them.

 

[maertz13]

Not sure if this is the main culprit, but looks like you have these 220p and 2n2 caps switched:

View attachment 48661

Also, you’ve soldered your ICs directly to the board instead of socketing them - looking at the amount of solder used (on the top side of the board - no idea what the underside looks like) you might have fried one of them.

you were right on all accounts. those were definitely in the wrong places. i knew my eyes were getting bad but i didn't realize i'd forgotten how to read . and as predicted, that didn't fix the bigger issue at hand. though i very much appreciate you spotting that. i imagine it would have sounded pretty bad with those values so wrong.

 

[temol]

Audio probe is your friend..

 

[maertz13]

Fresh op amps from a different supplier. Socketed this time in case they were bad. Lesson learned there. Replaced a resistor I’d broken. Reflowed every connection.

Annnnnd it still doesn’t work.

 

[Betty Wont]

That pcb looks roached. The soldermask is scratched to hell. Tons of exposed and/damaged traces.

 

[Nic]

You should remove the tabs on the pots so they sit flat inside the enclosure.

 

[Dirty_Boogie]

May I suggest a little more planning with your builds? Use sockets for ICs, transistors, and even for diodes. Order components that are size-appropriate to the board you're building (e.g., user lower voltage film caps, which are much smaller than those huge greenies), pull the components all the way through the board before you solder, so you don't have all those "floating" components (which are more susceptible to picking up noise), orient resistors with left-to-right color bands (makes troubleshooting easier when you can see resistor values more consistently.) There's pics of some crazy-good builds on this site, but for example, these are my Cetus build:

 

[maertz13]

all very reasonable and helpful advice. respectfully, it didn't work before i reflowed the board a half a dozen times and my helping hands scratched the board. they've been taped up since. if bunk op-amps weren't the issue, i'm hoping someone can spot what is. i bought enough parts to build 2, so i very well could just cut my losses and start over, but whatever error i made is likely to follow me to the next build, given the instructions are the same.

 

[JamieJ]

If you want to find out why it doesn’t work then you need to audio probe the circuit to see where signal doesn’t pass. Looking at the board a few traces between components look to be damaged so it’s not as simple as just reflowing components. The board has been over heated.

99% of builds that don’t work are due to workmanship issues. A big aspect to learn when building is soldering without over heating the components and board.

When starting out, the majority of people ending up ruining a few boards whilst learning what to do. Sometimes building a kit can be good to begin with to know what it best practice. Some like fuzz dog or Aion could be good to try because their documentation is really good.

We’ve all been there, it’s part of the learning curve.

 

[jesuscrisp]

DC Jack is wired wrong.

 

[maertz13]

DC Jack is wired wrong.

Can you elaborate? I couldn’t find any instructions on these jacks, and went with the “long side is positive, short is negative” approach.

 

[jesuscrisp]

The angled/square-ish looking lug is negative. The middle one you only need when wiring up a battery clip.

 

[Nic]

+1 on jack wiring

 

[maertz13]

Much appreciated. Is this correct?

Because it still doesn’t work . But I’m learning a lot here.

 

[drgonzo1969]

do you have covers or tape on those pots seperating them from PCB?

 

[maertz13]

do you have covers or tape on those pots seperating them from PCB?

i didn't at first, but i do now (and will do so moving forward)

 

[drgonzo1969]

any luck getting it working?

 

[drgonzo1969]

it looks like you might have a little solder bridge here

 

[maertz13]

it looks like you might have a little solder bridge here

I see what you’re seeing, it turns out that was a tiny bit of cotton from a qtip where I was cleaning up some flux

And no, still not working. I started the other board last night. Everything is super tidy this time. But I’m afraid that when I try to fire it up I’m going to have the same issue since I haven’t figured out why the first one doesn’t work (and hasn’t worked)