Anyone know why my Sunking II board keeps blowin' up?

[Scruffie]

Yeah.  Wow.  Did you already remove the zener?  Those currents shouldn't have burnt out the 10R resistor.  The voltages look good, too.

No those currents wouldn't but if the supply voltage wasn't steady (say it spiked), the zener may have been trying to level things out being a shunt regulator and the 10R wasn't correct for it to operate properly as such so it murdered the 10R trying.

Basically... zeners can really suck... figuratively and literally if something isn't right, they're okay for BBD voltage regulating (although I stopped using them) as current draw is pretty low so even if something goes wrong, if the resistor is large enough you're generally okay as something else would have gone wrong first usually anyway but to regulate an entire circuit, you have to really plan for them.

[upthepunxxx]

Not yet, I am going to try that when I get off work. Pull the zener, put r32 back, and see if it still heats up. Im pretty sure I haven't done it yet? It starts getting confusing trying to keep track of all this troubleshooting, especially when I have to do it over the course of a couple days! I do remember pulling the zener and measuring it on my DDM and it seemed fine. Not sure if they will still pull way too much voltage even if they check out on the meter...?

Yeah.  Wow.  Did you already remove the zener?  Those currents shouldn't have burnt out the 10R resistor.  The voltages look good, too.

[upthepunxxx]

the saga continues! So I fired up what I am calling board 1 last night (the original board that kept burning up r32). I replaced d3 and removed c6 (shouldn't change anything but i am not running the thick mod so there was no need for it). R32 was stable so I took some voltages. They were great the other night, but I think when I was checking them I some how shorted out out the regulator as I was getting some wacky voltages? Not sure what happened there but I changed it out anyways and rechecked voltages and everything looked the way they were suppose to. Only problem was that the volume pot still wasn't shunting signal to ground when turned all the way down. And the gain pot was still doing that weird oscillating octave sound when turned all the way down (it works fine when turned up.) I checked the 2nd board I made to compare and the volume and gain pots do the same thing?
Anyways, I decided to take Board 1 all the way back to stock, since I had successfully built two stock sunkings with no problems. I removed the jumper, wire and cap for the FAT mod. And you know what the gain pot stopped doing the oscillating octave thing! Im still having trouble wrapping my head around that one. The volume pot still won't shunt all signal when turned off.
So, I know what I will be doing this weekend, poking and prodding all weekend long trying to fix these boards. Im struggling with ordering more boards to try again and again until I get it right, however I think for financial and sanity reasons, figuring out what I am doing wrong first is the best option!

[upthepunxxx]

So the oscillating gain thing only happens when I have I the fat mod hooked up. Meaning I'm running alligator clips to a switch. When I remove it from the circuit (pull the clips). I can roll the gain knob all the way down without it doing that oscillation octave thing. Volume knob still won't completely kill the volume. I'm baffled. I searched the forum and didn't find anyother threads with this problem, so I just need to figure out what I'm doing wrong. I'm starting loose it boys 

[upthepunxxx]

I think I figured out my gain knob problem! I ditched the super long test leads and hooked up a toggle straight to the wires. Voila no more weird noises! So far so good. now i just have to figure out my grounding issue with the volume knob!

PS
I know you dudes are busy with your own builds, but "talking" this out and responding to my own posts has actually been extremely helpful, almost therapeutic! I keep havering to re read when I spell check my posts. It makes me double check everything I am doing to troubleshoot. I highly recommend forum published internal dialog!

So the oscillating gain thing only happens when I have I the fat mod hooked up. Meaning I'm running alligator clips to a switch. When I remove it from the circuit (pull the clips). I can roll the gain knob all the way down without it doing that oscillation octave thing. Volume knob still won't completely kill the volume. I'm baffled. I searched the forum and didn't find anyother threads with this problem, so I just need to figure out what I'm doing wrong. I'm starting loose it boys 

[upthepunxxx]

I have one more board left. I am going to try and recreate the build I did that worked, and hopefully that will help me figure out my problem with volume pot. If not then I am just going to keep ordering boards and troubleshooting till i get it! I feel I need a fresh start at this point. I've been staring at these boards every night trying to figure it out. I am sure I am way overthinking it and overlooking the obvious. So hopefully this starting over will give me a fresh new insight. Everyone else's volume control completely cuts off signal right?

[wgc]

I've got a build (different circuit) that's oscillating too.  I've narrowed it down to a few components but haven't yet dialed it in.

One thing that you might want to check into is the possibility of a mis-marked bag of parts.  Might be worth reordering some for your remaining pcb and see what happens. 

There have been times when I've caught myself almost returning parts into the wrong bag.

[blearyeyes]

I picked up a bench power supply that is DC 0-18v up to 2 Amps with auto shut off and adjustable voltage and amperage controls as well as Voltage and Amperage readout.
It was $49 bucks and I figure ten 9 volt batteries pays for the thing. You can set the amperage knob to just above where it cuts off. if you accidentally short the leads it shuts off the juice and as soon as you fix it it turns back on. You can also see how much power the pedal is drawing. I love this thing and think it was really worth it. If you're interested  PM me. I don't have any interest in these things and do not represent any company.

[upthepunxxx]

Thanks for the tip amigo! Luckily I figured out the oscillating problem. My only problem now is that whenever I turn down the volume pot all the way there is still a little bit of signal. It definitely lowers the volume to a point, but for some reason it's not all going to ground. I've checked my grounds on pin 1 and ever resoldersd the pot. I checked all the surrounding components too.

I'll def keep an eye out for bad part batches. However I make sure to test every component before I put it in the circuit. Only thing is my ddm can't seem to get a good read on is high value electrolytics.

I've got a build (different circuit) that's oscillating too.  I've narrowed it down to a few components but haven't yet dialed it in.

One thing that you might want to check into is the possibility of a mis-marked bag of parts.  Might be worth reordering some for your remaining pcb and see what happens. 

There have been times when I've caught myself almost returning parts into the wrong bag.

[mgwhit]

My only problem now is that whenever I turn down the volume pot all the way there is still a little bit of signal. It definitely lowers the volume to a point, but for some reason it's not all going to ground. I've checked my grounds on pin 1 and ever resoldersd the pot. I checked all the surrounding components too.

That might just be typical of the buffered version of this circuit.  Check out the top of the schematic where the post-buffer, pre-gain signal runs through C18 and R27...and notice how it connects directly to the output jack through R21 regardless of the bypass switch position.  How loud is it (compared to bypassed signal)?  Does it react to the Gain knob setting?  Again, I've never built this board, so hopefully someone who has will chime in.

[upthepunxxx]

Yea when the volume pot is all the way down the gain knob and tone knob have no effect on the signal and it's a lot quiter than the bypass signal. Well the bypassed signal from the jmk testing rig. I haven't boxed one of the these boards up yet since I was still unsure if I did something wrong. And when I have it hooked up to my testing rig I'm bypassing the switching. I just built another one to see what what would happen and it's doing the same thing.  Everything else works fine. I'm starting to think that maybe I am not doing anything wrong?? I built one for my buddy and he loves it. That's what I'm comparing it to. I don't remeber if the volume pot completely killed the signal? Maybe I never even checked? I haven't got to talk to him yet to ask him about the volume pot, but I'm thinking that maybe it does the same thing and I didn't realize it. I mean I guess you would never realize it unless for some reason you wanted the pedal off but didn't want to hit the switch? Not sure why you would do that? I am just mainly concerned about a grounding issue. Unless I'm completely off and it's not suppose to do that at all. I'm gonna check out the schem tomorrow per your suggestion.

Anyone built one that can check out the volume pot for me?

I really appreciate you still offering your help!!

My only problem now is that whenever I turn down the volume pot all the way there is still a little bit of signal. It definitely lowers the volume to a point, but for some reason it's not all going to ground. I've checked my grounds on pin 1 and ever resoldersd the pot. I checked all the surrounding components too.

That might just be typical of the buffered version of this circuit.  Check out the top of the schematic where the post-buffer, pre-gain signal runs through C18 and R27...and notice how it connects directly to the output jack through R21 regardless of the bypass switch position.  How loud is it (compared to bypassed signal)?  Does it react to the Gain knob setting?  Again, I've never built this board, so hopefully someone who has will chime in.

[upthepunxxx]

Problem solved!! So I went ahead and boxed one up thinking I'll if I want to turn down to volume all the way it means I want the pedal off, so I will just end up switching it off. Basically submitting to the fact that it was a totally livable problem, especially since i was pretty much just gonna play at high gain levels anyways. So I boxed it up  and voila! Problem solved. The signal is totally killed when you roll the volume pot down all the way. I'm not sure if it has something to do with connecting the pots to the enclosure ground or something with the buffer. I still need to figure that part out. I was just stoked it works!!

[murdog47]

Just fired up my buffered bypass Sunking II and it also set the 10R ablaze! I'll try the jumper.

[upthepunxxx]

Oh no! I feel your pain brother!  I socketed r32 and put a jumper in there to take voltages. Once I got my voltages stariaghtedned out I ended up replacing ic3 and d3. I was then able to put r32 back in without it burning up. Double check (and most likely replace) d3, but I'm pretty sure that's what was burning up r32 on my board. Let me know how it goes.

Just fired up my buffered bypass Sunking II and it also set the 10R ablaze! I'll try the jumper.

[murdog47]

Pulled D3.....R32 still smoking