Help debug my Nautilus?

[Natman]

Hi all, I finally got my Nautilus allwired up but it's not working right. I first had the footswitch done wrong but I figured it out. Now everything seems to except for one thing: the "wah" doesn't really trigger and the overall volume is way too high. I can hear the filters and all 3 switches are working but I only get the "w" sound, not "waaww" if you know what I'm saying. Any idea what should do?
Thanks!

[midwayfair]

Put the sweep at minimum and try both range settings. Any better?

Make sure R14 is 330R, not 330K. This would make the attack so long it wouldn't really do anything.

[Natman]

Thanks Jon, but it's a no go. R14 is right on spec. The filter is really not "opening and closing" as it should. My buddy built one at the same time as me and I know how it should sound.

Could my Vactrols be bad? I might have burned some component with too much heat?   

[midwayfair]

Thanks Jon, but it's a no go. R14 is right on spec. The filter is really not "opening and closing" as it should. My buddy built one at the same time as me and I know how it should sound.

Could my Vactrols be bad? I might have burned some component with too much heat?   

Doubtful. They're as robust as a resistor and an LED, which is what they are.

Does your filter indicator LED light up when you play?

[Natman]

Yes it does!

[chordball]

Have you tried swapping in new IC's? I built mine and it worked great, started doing some mods, then one day it didn't work so well. It turned out that one of the TL074's had gone bad. It still had volume but the filter didn't work.

[peAk]

My Nautilus had issues until I removed the vactrols and put new ones in. I couldn't get a good filter sound on the "sweep up" section

As silly as it may sound, I socketed the vactrols the second time around and after the change, it worked perfect.

[Natman]

Have you tried swapping in new IC's? I built mine and it worked great, started doing some mods, then one day it didn't work so well. It turned out that one of the TL074's had gone bad. It still had volume but the filter didn't work.

Dag, I sure hope not -they're not socketed and I don't have spares! Is there enough data out there that would allow my multimeter to locate the problem or is that wishful thinking?   

[muddyfox]

I'd give you my voltage readings but my Nautilus is still not built (and I've had the board for at least a year). Hopefully you'll fix yours way before I actually build mine. 

[midwayfair]

Yes it does!

Measure across the vactrols' LDR sides. Does their resistance change when you play?

[Natman]

I'll check. in the meantime, here's a gut shot. I can't find anything wrong and my solder joints look clean.   

[Natman]

Yes it does!

Hey Jon yes they do. I notice I have to hit the strings very hard to get a change however. Still is not making the open & closed sound you expect!

Measure across the vactrols' LDR sides. Does their resistance change when you play?

[midwayfair]

Audio probe pins 14 and 8 of IC2.

You're losing signal somewhere in the envelope section.

Also, you're not doing yourself any favors trying to troubleshoot this when it's boxed up.

[Natman]

I finally got around to checking all of my resistances and it turns out the 5k Sweep pot is bad, reading over 12 Megs. I think this might be the problem  

My R5 is also off, reading 124k instead of 390k. So I'll replace these parts and see what happens.     

[midwayfair]

I finally got around to checking all of my resistances and it turns out the 5k Sweep pot is bad, reading over 12 Megs. I think this might be the problem  

My R5 is also off, reading 124k instead of 390k. So I'll replace these parts and see what happens.     

If you're measuring in-circuit, the 390K may very well read significantly lower.

The sweep pot sounds like it's not connected, or perhaps the pot itself is broken. I'm pretty sure there aren't 12M pots in your parts bin that you could grab by accident!