Sunking troubles

[chip46]

So I finally got around to building my Sunking, but I'm having a few issues. Hopefully it's something silly I'm overlooking.

Basic rundown of problems:
1) I haven't wired the LED up yet, just connected via jumpers. When I plug the 9V in to the pedal, the LED is always on, pedal bypassed or not.
2) I'm not getting a lot of gain out of the pedal. It's basically a clean boost.
3) The gain knob is working in reverse. The tone and volume are working fine and in the correct orientation, but the gain knob (which doesn't add any gain) seems to be working backwards and only adds more volume, when full clockwise I get less volume and a muddy-ish signal.

Steps I've taken:
-Replaced all the IC's in the odd case that I got a borked IC
-Replaced the 2 socketed diodes (I'm using BAT41's)
-Checked over all the solder locations on the back of the board to look for solder bridges or bad joints. I see none.
-Checked all offboard wires to make sure I don't have any weird/broken wires. There were none.
-Checked orientation of all parts. Check.

I have yet to get voltages off the IC's but it's late so I will do that tomorrow, as well as take pics if needed.

The LED issue leads me to believe something is wrong with the switch, but the switch works fine because I can switch from the pedal to the bypass signal just fine. It could also be because the LED is never seeing the switch and is just getting direct power from the 9V source, but I don't see any cold joints for the LED switch wire.

I noticed that 25V electrolytic caps are needed for this build, and I'm pretty sure that most of the ones I used were 50V, but I'm not positive, there may be some 16V in there. Would this be a problem? The gain issue is odd because I'm using a Les Paul style guitar with humbuckers, so I should at least be getting some kind of distortion/clipping. Could it be associated with the diodes? Maybe bad sockets that aren't holding the diodes correctly or connecting with them properly? I can take the diodes out of the sockets and I don't hear a whole lot of difference, so I'm beginning to think that's the problem. This is probably my 6th or 7th build, and I usually don't have problems like this, so I'm walking away for a bit to try again in the morning.

Thanks for any help guys, and I'll get the IC voltages and pics tomorrow.

[jkokura]

My suspicion is that you've done something wrong, and it's very simple. It could be that a diode is backwards, or your wiring is incorrect, or something innocuous like that.

Pictures and voltages would help. Also, check all your parts one by one and ensure that they are both the correct value and installed correctly.

Jacob

[cjkbug]

double check that both diodes are oriented with there stripes facing the same direction and not opposite directions, the sunking's layout is different from most od clipping sections in this regard. don't know if that's it but give it a looksee just to be safe. I did that on my first sunking and it didn't sound right till I fixed it.

[chip46]

No it's not the diodes, I know better than that. 

The only subbed value I had were two resistors I put together to get the 422k, I used a 390k + 33K.

[gtr2]

For the 422k...  did you put the resistors in series or parallel?

[mgwhit]

Your footswitch should be providing a path to ground for your LED only when the effect is engaged, so if your LED is on all the time either your switch is broken or you have it miswired (or something is accidentally shorting).  Disconnect your "jumper" between the LED and the footswitch  and test that lug with a digital multimeter.  If it's grounded in both footswitch positions you need to figure out what's going on on your footswitch (pictures always handy).  If that lug isn't grounded when the effect is off, then maybe whatever you're using to clip the LED to it is shorting.  If the LED is on when it's not even connected to the switch, you could have a short to ground directly on the board.

You have said that you're not getting much gain and that it's really only acting like a clean boost.  I'm assuming that by "gain" you really mean "distortion".  If the volume is effectively getting significantly louder than unity gain, and you're not getting distortion, that suggests that your Germanium diodes aren't connected properly.  What kind did you use? (1n34a?)  If you socketed them, they may not be making good connections.

If you're only getting slightly more than unity gain, then your op-amps aren't amplifying correctly and the amplified signal may not be large enough to be clipped by the diodes.  The fact that your gain knob works backwards already suggests that something is wrong in that department.

I don't see any caps that need to deal directly with 18VDC except C20 and C21, but I still wouldn't be happy having any 16V caps on this board.

I think you know the drill: check voltages, post pictures, signal probe.  Good luck!

[chip46]

For the 422k...  did you put the resistors in series or parallel?

Series

^I've been thinking about the footswitch, It was a DPDT I had laying around, but I've got plenty of 3PDT so I may just go ahead and replace it.

Yeah by gain I was talking about distortion, the pedal still gets plenty loud, but it's just a glorified clean boost at this stage. I don't know why the gain pot is acting in reverse, it's wired correctly and is a standard linear taper (B) pot, dual-ganged obviously.

I just woke up so give me a bit and I'll bust out the multimeter. Thanks guys.

[chip46]

Well I did notice something odd on the PCB. I took all the wires going to the switch off of the pcb so that I could start over with a different switch, and when I got the wires out of the pcb I noticed that the silver rings around the pads on top of the board weren't there. They didn't come off when I desoldered the wires because I would've seen the rings still attatched to the wires if that were the case, and I didn't even have the iron on those spots for very long.  

Is it possible the pcb came this way? I know it's a far shot that something like that would happen but for the life of me I don't know how or when they could've come off. I guess I'll have to take a look at the schematic and connect the parts with jumper wires since I'm assuming without the pads the signal wouldn't flow properly, which is probably why I was having trouble in the first place.

[gtr2]

I've desoldered some rings off before accidentally (I was a bit too impatient).  It doesn't take much to do it and those little rings can be hard to see.  Most of the time there is enough of the pad still sitting in the pcb that you can solder your wires in without an issue.  I always just make sure I have continuity after resoldering.  Once I changed my desoldering method I don't have a problem anymore with pulling off the pads.

Josh