Strange problem with Octagon FV-1 build

lumberjack

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Hey gang, I'm having an odd problem with my recent Octagon build. When I first built it the last four effects in the selector switch worked, other than the fact that the harmonic trem seemed weak/off somehow.

Fastforward a week or so, and now when I turn the selector knob through all 8 modes, the last four modes are just the first four modes repeated again. Mode 5 is the same shimmer reverb as mode 1, mode 6 is the modulated verb from mode 2 again, and so on. So I no longer have access to those last four modes somehow.

Not a terrible issue even if I can’t resolve it, as my favorite of the bunch is the modulated reverb which still works great. But I can’t for the life of me figure out why they would have worked before and now they’re replications of the first four modes.

Is my FV-1 soldering to blame here? You can see there’s more solder than necessary perhaps, and some of it is flaring off the legs, maybe some of my joints aren’t good? The other thing that crossed my mind is maybe a glitch/error in the EEPROM chip, such that those last four algorithms are now copies of the first four. No idea where to begin trouble shooting this as I’m very much an FV-1 noob. Any insight would be much appreciated.
 
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There are a few other pins down that same side that look as if the solder hasn't flowed well too. 18 looks the worst. I have to admit that if I reflowed 18 and everything then worked properly I would leave the rest alone :)
 
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Try soldering first. If that doesn’t solve it, it’s possible the rotary switch has failed internally. You could test that by looking at the voltage on R17 (one leg will be ground, the other leg should be 0v in modes 1-4, 3.3v from mode 5-8)
 
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Hey guys, that worked perfectly! I reflowed legs 16-20 and the pedal is now working perfectly. I was tempted to reflow some more legs cause they don’t all look great, but if it’s working it’s working and I can reflow those other legs down the line if something goes wrong with them. They seem to have good connections now anyways.

Thanks so much for the help, I really appreciate it! And hot damn some of the effects in this chip are just beautiful
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Hey guys, that worked perfectly! I reflowed legs 16-20 and the pedal is now working perfectly. I was tempted to reflow some more legs cause they don’t all look great, but if it’s working it’s working and I can reflow those other legs down the line if something goes wrong with them. They seem to have good connections now anyways.

Thanks so much for the help, I really appreciate it! And hot damn some of the effects in this chip are just beautiful
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I found that it helps to flow some liquid flux along the legs of the FV1. Actually I put a healthy bead of flux down before soldering. It helps the solder flow to the leg and pad and not stick to everything else (like the next leg:)) Also, you've probably got too much solder on most of those legs. I'd get a solder wick (again flux the wick down) and wick some of the excess solder so it's not such a big bead.
 
It's not clear from the photos whether there's solder between the lead and pad. That blob of solder on top of the lead doesn't make a connection, it just obscures the view. Soldering SMDs is not easy.

There's a technique I learned call "drag soldering." You apply a light coating of flux to the pads, place the FV-1, get a bead of solder on the iron tip and gently drag the tip down the row of leads. A small amount of solder deposits on each lead. Takes a few tries to get the hang of it. It's easiest to install SMD ICs first and then inspect each joint with strong magnification. I tape the part down with Kapton so it doesn't move during the soldering process.
 
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