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!
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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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.
Quote from: ch1naski on August 26, 2013, 03:39:08 AM
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......
Sent from my Nexus 7 using Tapatalk 4
Thanks for the answer, I don't think there's a charge pump in there though...
Quote from: juansolo on August 26, 2013, 08:17:34 AM
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!
Quote from: MattL on August 26, 2013, 03:31:11 PM
Quote from: ch1naski on August 26, 2013, 03:39:08 AM
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......
Sent from my Nexus 7 using Tapatalk 4
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!
I also suggest replacing the zener. I wouldn't say it's designed to blow, just that it will usually do so if the power supply polarity is backwards, or if it's subjected to a higher voltage than the zener rating. My recommendation would be to put a 1N5817 in series with the power supply voltage. It'll drop a half volt off the V+, but you probably won't miss it, and it will protect against a reverse polarity connection.
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!
Google the data sheet for the charge pump IC. Find which pin puts out your 18 volts, and check that it is putting that out with your meter.
You may be able to tell which pin to test by looking at the schematic, I don't have it handy to look at it.
The output voltage of the charge pump can be measured at pins 8 and 4 of IC2 (I have the version 3 schematic if that makes a difference). You can't really measure the boosted voltage from the charge pump itself since it comes from the capacitors and diodes.
As a note, the zener voltage regulator on this has an issue (although from what I can find it does look like it follows the original design). When the voltage goes over the zener limit, the current rise is essentially asymptotic. It's going to be limited by the power source but this still isn't good and it could cause problems. The design needs a current limiting resistor at the power input. The value for the resistor can be determined from current needs of the pedal.
A quick web search turned up this page with a calculator http://www.reuk.co.uk/Zener-Diode-Voltage-Regulator.htm (http://www.reuk.co.uk/Zener-Diode-Voltage-Regulator.htm). I've seen others before that give more info. Anyway, you could put a small value resistor at the power input to protect the zener (and power source).
Edit: I should note that this is only going to be an issue if you plug in a power source greater than the zener voltage. If you know that you won't do that, it isn't a problem.
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
Quote from: MattL on August 27, 2013, 05:31:42 PM
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?
Quote from: RobA on August 27, 2013, 06:14:22 PM
Quote from: MattL on August 27, 2013, 05:31:42 PM
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!
Quote from: MattL on August 30, 2013, 04:19:45 PM
Quote from: RobA on August 27, 2013, 06:14:22 PM
Quote from: MattL on August 27, 2013, 05:31:42 PM
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.
Quote from: rullywowr on August 26, 2013, 04:59:02 PM
Quote from: MattL on August 26, 2013, 03:31:11 PM
Quote from: ch1naski on August 26, 2013, 03:39:08 AM
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......
Sent from my Nexus 7 using Tapatalk 4
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?
You need to check the op amp voltages with the op amps on board to get the voltages on all the pins. You could check just the supply pins at the pads with no op amps in place to get the levels there.
The resistor just needs to be put in front of the power input. You could actually just solder it in to the lead the same way you might for an indicator LED resistor. For now though, as long as the zener is up there in the 12V range and your input is at 9V, that shouldn't be an issue.
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?
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?
Quote from: RobA on September 07, 2013, 09:55:33 PM
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!
It certainly can't hurt to build it again. Which IC do you have for the charge pump.
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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Quote from: ch1naski on September 08, 2013, 05:09:13 AM
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
Sent from my Nexus 7 using Tapatalk 2
Good suggestion, thanks!
Quote from: RobA on September 07, 2013, 10:51:52 PM
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.
Quote from: MattL on September 09, 2013, 02:10:57 PM
Quote from: RobA on September 07, 2013, 10:51:52 PM
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!
Quote from: MattL on August 27, 2013, 05:31:42 PM
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.
Are you testing the board inside the enclosure still? I would suggest taking it out if you haven't already and checking over the outboard wiring. Since the wiring is particular on this build you want to make sure you have everything right. From your description, it does sound like the output is working however it could be something as simple as a shorted or not connected ground on the input jack. Especially if you used the housing as a ground and didn't run a ground wire from the sleeve of each 1/4" jack.
If that fails, then I would whip up a simple audio probe out of a 1/4" guitar cable. Tie the sleeve to ground and use the tip as a probe (with a solid wire or something). Plug this cable into your amp or whatever. Trace the input signal from the "IN" pad and follow it through the circuit. At some point it will cut out and then you can narrow down your potential issue.
Also check voltages on all the IC's respective pin (usually pin 8). If you got nothing, it would suggest a problem with the power supply or feed circuit.
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.