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I've actually tried in and out of the enclosure...I have a test rig, thanks to the wisdom of the fine people on this site? I didn't choose the more specific wiring, the buffered version, but instead went for the true bypass version, ala the stock Madbean version. Lots of time I use the more standard method of true bypass, the popular "easy" version with star grounding...I may try that, unless anyone has a reason it shouldn't work. That one I feel comfortable with, as I have it memorized. I was getting close with the Madbean version, before I went on my unplanned pedal building hiatus (to build guitars). I don't think it matters which of those I use, but I don't want to get involved in the buffered version...i see no point. I don't use super long cables, etc. But I digress! Anyway, the pedal had been sold and used regularly for at least six months before it blew, so having reflowed all the solder and replaced the suspect components, I'm a bit at a loss. I'm finished with the second board, just waiting for the 390nf cap.

It certainly can't hurt to build it again. Which IC do you have for the charge pump.

MAX1044. Since none of the components hadn't been replaced that were in question, meaning all IC's, as well as diode 3, I'm at a loss. All solder has been re-flowed. Anything else that can blow other than these things? Some people have mentioned other component failure, but every time I suggest component failure on the forum, people act like I'm an idiot, and say components almost never fail.

To clarify, all of those components HAVE been replaced!

It certainly can't hurt to build it again. Which IC do you have for the charge pump.

MAX1044. Since none of the components hadn't been replaced that were in question, meaning all IC's, as well as diode 3, I'm at a loss. All solder has been re-flowed. Anything else that can blow other than these things? Some people have mentioned other component failure, but every time I suggest component failure on the forum, people act like I'm an idiot, and say components almost never fail.

If you liked the sound with the smaller value cap, maybe you should socket it in the next build. Just in case your  "erroneous" ;)version sounds better to your ears than the stock cap

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Good suggestion, thanks!

Just to be sure we are looking at the same thing, the schematic I have is for the V3 doc and it shows the 390nF cap being C5 (C4 is 68nF). It is going to have an influence on the sound of the pedal. It's going to change the frequency response as the gain is changed.  Although, this is going to be a pretty complex thing since the gain structures of the two stages are intermixed and there's multiple feedback points involved. So, without simulating it, I really don't know how much it'll alter the sound. I wouldn't think that this by itself would have anything to do with the pedal blowing.

Did you make any other parts substitutions? I can't remember the whole conversation in the thread going back at this point, did you get the voltages on the IC's?

Not yet...I started building the second board. It was actually as I started to fill the BOM of a Guitarpcb.com miniklon that I discovered I didn't have the 350nf, nor was there evidence that I had. So I checked back on the other build, and noticed I'd used the wrong value in both Sunkings. I have some on order anyway. I haven't gotten back to the other one because I kind of gave it up in favor of a new one, since I had two boards, and I needed to "borrow" the pots. I am going to get back to it...I have replacement pots on order too, and I value and appreciate all your help and information...thanks!

I just discovered that I had erroneously put a 39n instead of a 390n for C4. Two questions:
1. the pedal had still sounded very good...is this a capacitor not relevant to the sound, and
2. could this be the cause of the pedal blowing?

Diode? 1n4742 in particular?
And is the charge pump still putting out correct voltage?
Just ideas, from other people's problems I've read about......

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Thanks for the answer, I don't think there's a charge pump in there though...

All good information.  There most definitely is a charge pump in the Sunking, it is IC3.  If a incorrect (edit: reverse) voltage is applied to the pedal, the zener is supposed to protect the charge pump (IC3) by blowing.  Depending on the charge pump, I have heard that many of them do not like getting more than 12v.  Check/replace the zener first.  After that, check the positive side of D5 or the positive side of C21 to see if you are getting 18v.  If not, the pump may need to be replaced.  Let us know how you make out!

Can I check these voltages on board, or do they need to be removed?

So is the design flawed? I know it's not made anymore, and a lot of these answers seem to be work arounds to getting it to work as it originally should have...

I have replaced diode 3 to no effect. Also, when hooked up to my test rig, with effect engaged, I don't hear anything that I'm supposed to, like guitar, but I notice the gain control can be heard to increase or decrease hiss, which makes me quess that the output is working. I have another of these boards that I'm going to make, but it seems that there are common problems with this, particularly based around charge pumps etc. Any suggestions as to how to avoid this in the future, or is it just the design? Thanks

No, I wouldn't say the design is flawed. If all the parts are right and the input voltage is right, then it should be fine.  It's just that with the addition of 1 extra resistor, it could have been made better. This pedal is basically OK with the 12V zener in there and a 9V power supply.

Charge pumps in general are fine and do the job of getting higher voltage and negative rails from 9V single supplies well. There are some issues with charge pumps and using the right one in the right way is important.

Also, you don't know yet what is causing your problem, it could be entirely unrelated to the charge pump and the zener. They just seem like good places to look first because of how the pedal died over time. It could be something like a cap gone bad or a cold solder joint that's become an issue too.

Did you get the voltage readings from the two op amps?

Hi, I have reflowed solder, I have changed out the opamps (I assume you mean the 72's, but I've changed them all) I have changed the zener also. I don't understand where to add the resistor, but since I've got another of these boards that I'm about to get started on I'd love to know, as well as how to check the voltage on the opamps!

Oh, sorry, I see you've already included info about the opamp voltage.

So is the design flawed? I know it's not made anymore, and a lot of these answers seem to be work arounds to getting it to work as it originally should have...

I have replaced diode 3 to no effect. Also, when hooked up to my test rig, with effect engaged, I don't hear anything that I'm supposed to, like guitar, but I notice the gain control can be heard to increase or decrease hiss, which makes me quess that the output is working. I have another of these boards that I'm going to make, but it seems that there are common problems with this, particularly based around charge pumps etc. Any suggestions as to how to avoid this in the future, or is it just the design? Thanks

No, I wouldn't say the design is flawed. If all the parts are right and the input voltage is right, then it should be fine.  It's just that with the addition of 1 extra resistor, it could have been made better. This pedal is basically OK with the 12V zener in there and a 9V power supply.

Charge pumps in general are fine and do the job of getting higher voltage and negative rails from 9V single supplies well. There are some issues with charge pumps and using the right one in the right way is important.

Also, you don't know yet what is causing your problem, it could be entirely unrelated to the charge pump and the zener. They just seem like good places to look first because of how the pedal died over time. It could be something like a cap gone bad or a cold solder joint that's become an issue too.

Did you get the voltage readings from the two op amps?

Hi, I have reflowed solder, I have changed out the opamps (I assume you mean the 72's, but I've changed them all) I have changed the zener also. I don't understand where to add the resistor, but since I've got another of these boards that I'm about to get started on I'd love to know, as well as how to check the voltage on the opamps!

So is the design flawed? I know it's not made anymore, and a lot of these answers seem to be work arounds to getting it to work as it originally should have...

I have replaced diode 3 to no effect. Also, when hooked up to my test rig, with effect engaged, I don't hear anything that I'm supposed to, like guitar, but I notice the gain control can be heard to increase or decrease hiss, which makes me quess that the output is working. I have another of these boards that I'm going to make, but it seems that there are common problems with this, particularly based around charge pumps etc. Any suggestions as to how to avoid this in the future, or is it just the design? Thanks

I did try replacing IC3, as well as the other IC's, but didn't help. I'm now going to try replacing the zener, but I'm wondering how to check if the charge pump is putting out correct voltage? As you can see troubleshooting is a big weakness for me, because I see the "how" of building, but not the "why". Any recommendations on literature would be greatly appreciated!

Check for ground at the other side of the zener. If it's there, swap it out. I've had one pop before when it had something it didn't like from the PSU.

Thanks, I'll try changing that!

Diode? 1n4742 in particular?
And is the charge pump still putting out correct voltage?
Just ideas, from other people's problems I've read about......

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Thanks for the answer, I don't think there's a charge pump in there though...

I was wondering...I had been building lots of pedals, but last November I got the building parts guitar habit going, and I guess I don't have time for both obsessions at a time! Anyway, a Sunking I made (double sided, V.3, I believe) that had worked fine just kicked the bucket. Wouldn't matter that much, but I had sold it to a friend, and when I tried to figure out what was wrong, I failed miserably. Normally I'd expect the problem to have been in the switch or the outboard wiring, as I haven't heard much about components just suddenly stopping working. But the switch was okay, and the solder was all reflowed. The ins and outs, board and jacks, were checked. Grounding, and potential for anything grounding out inside was checked. I changed out the Opamps...all good. Anybody else ever have this happen? My problems have been more not getting them to work to begin with, but never having one fail that had previously worked. But I've built around 85 successfully, and in all honesty, I'm stumped! Any ideas would be greatly appreciated.
Thanks!

Hmmm, at first I was thinking guitarpcb.com, but when I enlarged it it didn't look to be of the quality of either them or madbean in their etched days (both have since to a large extent switched over to double sided boards). I think it looks like somebody's earlier attempt...the etching isn't that clean.