# Octagon not working



## 83Metality (Dec 26, 2021)

Hello,

I've built the Octagon, but it had a lot of white noise. All the effects worked, but too much noise, so I thought I wanted to have a listen here.  Now that the effect is out of the board, it has signal when disengaged, but only noise when engaged and the EEPROM gets really hot. Any ideas what could be wrong?


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## carlinb17 (Dec 26, 2021)

I would start with going through and cleaning up the soldering, the FV-1 chip looks like there could be bridges, one of the lugs to your volume pot could definitely use more solder, then trim the excess leads off the resistors etc on the back side. It also looks like you have at least one strand of your power in wire possibly touching ground. I see you socketed on elf the chips but not the EEPROM? this may be an issue if something was shorted.  You still have the tabs on each pot? If you box this it won't sit right and cause strain on the joints, this can be snapped off. I recommend Reflow and let us know. I'm sure someone else will have more for you.


edit: sorry not elf chip but TL074 chip...I'm clearly fried from Christmas.


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## JamieJ (Dec 26, 2021)

I agree with @carlinb17 
Good points to get started with.


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## 83Metality (Dec 26, 2021)

Thanks for the help! Sadly couldn't revive it. IC6 is getting really  hot and it just makes a loud humming noise when I turn it on.


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## Jonnytexas (Dec 26, 2021)

Looks like you might have a short between the red and black wires right above the FV-1 from a strand of wire.  Also looks like you might have missed soldering a lug on one of the pots.  FV-1 soldering looks a little rough.


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## 83Metality (Dec 27, 2021)

Jonnytexas said:


> Looks like you might have a short between the red and black wires right above the FV-1 from a strand of wire.  Also looks like you might have missed soldering a lug on one of the pots.  FV-1 soldering looks a little rough.


A little rough is in understatement ... I used 1mm solder and jumped a bit too fast in it. I redid it a couple of times. 
I've built a few boards with success. After this disaster I finished a Quantum Mystic clone, but this board seems fried. I'm ordering some practice SMD boards, 0,5mm tin and solder flux before I give this another shot.


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## Mcknib (Dec 27, 2021)

Your eeprom pin solder joints look a bit sparse especially pin 4 ground that looks to have very little solder on it


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## Jonnytexas (Dec 27, 2021)

You 100% did nor solder one pin of the B100k pot.  I think the FV-1 could be fixed.  There are two spots that appear to have bridges.  Suck those out with a solder sucker and reflow. Even though it's ugly, it will probably work.  Anyways, good luck.  I threw away a couple of FV-1 boards when I was starting out because of awful SMD soldering.


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## PJS (Dec 27, 2021)

My first attempt at SMD soldering was a DSO138.  It is a bit complex but not too bad.  The really tiny microcontroller is already soldered in the factory.  Most complex part is a 14 pin op amp, which gives good introduction for something like a FV-1.  At the end you have a cheap and OK-ish oscilloscope that can handle any audio frequencies.


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