Can circuits be damaged if a 9V power connector touches the output jack ?

[GibsonGM]

Ok, first thing I see is that 1st opamp's output pin 7 (IC1 TL72) is at 9V (supply voltage). Either there's a solder bridge to pin 8 under the socket, or a problem.  Maybe C14 is popped, and D8 not connecting to Vref but to 9V (??)  Look at that cap and the diode too.

Sorry, time to watch a movie with my wife, but I'm sure others will see this shortly!   Check pin 7...that alone will cause major problems if the reading is correct.

[eh la bas ma]

Ok, first thing I see is that 1st opamp's output pin 7 (IC1 TL72) is at 9V (supply voltage). Either there's a solder bridge to pin 8 under the socket, or a problem.  Maybe C14 is popped, and D8 not connecting to Vref but to 9V (??)  Look at that cap and the diode too.

Sorry, time to watch a movie with my wife, but I'm sure others will see this shortly!   Check pin 7...that alone will cause major problems if the reading is correct.

I wish you a pleasant evening !

Just checked the TL72 again, and i have different results at pin 7 this time. Might be related to IC2 being replaced by a TL74, i'll check that too.

IC1 TL72

1= 5.15     8= 9.46
2= 5.08     7= 5.45
3=4.68      6= 5.45
4= 0V       5= 4.88

Edit : I put back the LM324 and read 4.80V at IC1 pin 7. Crackling noises are gone, Octaves still sound better... No idea why it's fixed now.

Maybe it was something unrelated to reversed voltage, a tiny piece of hair on the circuit that i didn't notice... I can't say at this point.

There was some issues until i changed LM324 with a TL74. The issues disappeared. I put back the LM324, it's still fine...

In conclusion, Spectron and OC-7 both are back to normal after one day or two of tinkering. I suspect it was either some dirt in the circuits, or some cap got accidentally loaded when the output jack touched the 9V connector, and it took some time to unload, thus creating a few issues during this lapse of time.

Hoping this is permanently fixed, I won't let output jacks touch any 9V connectors ever again. It can't be good in any case.

Thank you very very much for your help !

[GibsonGM]

Yes, you may have 'fixed' something by opening the circuit(s).  Maybe a small piece of solder was wedged between two components and fell off...or an offboard wire is fragile and about to break, but you have bent it in a way that it now works!!   Switch connections perhaps....perhaps.   If it's not broke, don't fix it! 

This probably underscores why slow, steady, neat and clean work using new components and good wire, good solder, proper soldering technique/heat...are crucial to a reliable, solid build!

I would not be fearful of 9V on input jacks, but I wouldn't do it intentionally, no, ha ha.

[eh la bas ma]

Unfortunately, there are still some crackling noises on the OC-7.

https://www.delykpcb.com/product/up-down-daddy-pcb/?attachment_id=1089&download_file=k0sve9jvlkveb

The noises appear only when the circuit is switched on with the Octave Up turned on.

If I set Oct. up control fully CCW and activate the circuit, it's working and perfectly silent. It remains silent when i turn this control up after switching on.
No cracklings, and the Oct. up pot is rotating silently.

If the Oct. Up knob is set anywhere CW when switching the effect on, there are some random crackling noises, also sensitive to the signal (more cracklings if i am strumming the strings). The Oct. Up pot also become slightly noisy, with some "shhhh" sound when i turn it.

I measured VR, i read 4.88V when switched off, 5.36V when switched on, at R2 and Oct. up pin 1.
Reflowed all suspicious pads, checked for shorts, tested all diodes with a DMM on diode mode, everything seems fine.
Next, i'll try to track down the cracklings with an audio probe.

So, the effect can behave correctly, but only as long as the Oct. Up control is set CCW when i switch the stompbox on.

I wonder if this can reveal some kind of indication about the issue ?

[GibsonGM]

The effect works besides this 'crackle'?   I, for one, am curious where there is DC on these pots with no cap from wiper to ground, at least.  Maybe I'm not seeing something, but any time there is DC on a pot, the symptom is CRACKLE.  All it requires is a few mV of DC to make noise.

Yes, please audio probe and locate where this noise starts.  Even if you have to lift a resistor to do so. 

[eh la bas ma]

Audio probe test is harder than usual because i am looking for random cracklings popping upon activation. They tend to disappear after a few seconds, and there aren't some cracklings every time i switch the effect on. More like 1 out of 3 times, it's a bit random.

The audio probe can make some cracklings of its own, when the probe moves even slightly on the pad.

I have to switch on an off several times while probing a part, hoping to hear something during the first three seconds...

Not sure audio probing test is very useful in this case ?

I guess i'll replace all electrolytics, if it doesn't work i'll replace all ICs too, and hope for the best...

Edit :

The effect works besides this 'crackle'?   I, for one, am curious where there is DC on these pots with no cap from wiper to ground, at least.  Maybe I'm not seeing something, but any time there is DC on a pot, the symptom is CRACKLE.  All it requires is a few mV of DC to make noise.

Yes it works, and it's a relief.

I'd like to try to check this DC risk that you described, see if it solves the issue.

Would it be possible to do add a DC blocking cap on the Octave up pot ?

[GibsonGM]

The pot using Vref as ground is part of its design      The other pots and ICs are using Vr as well, and don't appear to have an issue.  Makes sure you install a new 324 - bring the circuit back to the way it was designed, first!   If you wish to change the electro caps, do so.  Then test again.  There is a reason the crackle happens on that and not the others.

All I can think of doing now is to aggravate the problem. Make it worse.   Wiggle the wires, push the ICs around a little bit, tap on the switch contacts with a pencil eraser, bang the jacks, wiggle power wires.   Bend the PC board gently with the pencil eraser. 

[eh la bas ma]

I changed all ICs, all electrolytic caps, and still have the same issue.

At least I know that they weren't the cause of the cracklings.

Time for some serious hunting for shorts...

[antonis]

I don't like all those pots going to Vref...

P.S.
Are you sure for 100μF Vref cap health..??

[GibsonGM]

^  I thought I was alone on that....why do they all go to Vref? That's putting DC on those pots. It seems like a design flaw, from my POV.
     
Yes, the bypass cap - if that were damaged, there would be no 'smoothing', and allow for more variation in Vref due to changing current demand (pots)...

Time for some serious hunting for shorts...

Justin, you have much ambition for pedal building. I admire that!  The time you invest now to learn how to debug pedals will serve you well in the future.
May I suggest that hunting for shorts comes early in the process?

When building from a kit, or assembling your own PCB, it is easier to connect jacks and battery power using jumpers with alligator clips, and test the circuit with a guitar and amp BEFORE installing the switches and power jacks.   This way you know the board works, and any future problems are likely in the switching or power jack.   If you did that, please forgive me.   I am curious is this problem has existed, or was 'caused' by the problem with the power plug...hmm. 

The second part of the process (now) would be to hunt for those shorts (!!), make sure all wiring is going where it should.  Assure the stomp switch is not damaged.  Ensure the power to the board is not somehow a problem.  Are the guitar cables ok???

If you cannot find the problem this way, I would remove the PCB from enclosure, and remove the switching and power jacks.  Then go back to using jumpers and a battery to isolate the PCB.   This is only how I would do it, others may vary.   Without power, we can test diodes, transistors and caps (to some degree).  At least we can eliminate the jacks/switching from the problem.

If necessary, one can isolate an individual circuit block by lifting a couple cap or resistor.  The audio probe will be your best friend in this hunt, but first your EYES must be used many times to ENSURE that you assembled it correctly!       If we chase problems blindly by making assumptions, this is called "easter egging", where we HOPE to stumble across the solution.  But it is usually faster to follow a firm method.    You will learn this as you go 

[antonis]

^  I thought I was alone on that....why do they all go to Vref? That's putting DC on those pots. It seems like a design flaw, from my POV.

Not for an IDEAL world designer..
(no DC offset across pots resistive element..)

[eh la bas ma]

I don't like all those pots going to Vref...

P.S.
Are you sure for 100μF Vref cap health..??

Thank you for the suggestion.

I just changed it, with a brand new 100 uF cap from the local electronic shop. I guess it's ok, but i'll check its connections with some continuity tests anyway...

^  I thought I was alone on that....why do they all go to Vref? That's putting DC on those pots. It seems like a design flaw, from my POV.
     
Yes, the bypass cap - if that were damaged, there would be no 'smoothing', and allow for more variation in Vref due to changing current demand (pots)...

Time for some serious hunting for shorts...

Justin, you have much ambition for pedal building. I admire that!  The time you invest now to learn how to debug pedals will serve you well in the future.
May I suggest that hunting for shorts comes early in the process?

When building from a kit, or assembling your own PCB, it is easier to connect jacks and battery power using jumpers with alligator clips, and test the circuit with a guitar and amp BEFORE installing the switches and power jacks.   This way you know the board works, and any future problems are likely in the switching or power jack.   If you did that, please forgive me.   I am curious is this problem has existed, or was 'caused' by the problem with the power plug...hmm. 

The second part of the process (now) would be to hunt for those shorts (!!), make sure all wiring is going where it should.  Assure the stomp switch is not damaged.  Ensure the power to the board is not somehow a problem.  Are the guitar cables ok???

If you cannot find the problem this way, I would remove the PCB from enclosure, and remove the switching and power jacks.  Then go back to using jumpers and a battery to isolate the PCB.   This is only how I would do it, others may vary.   Without power, we can test diodes, transistors and caps (to some degree).  At least we can eliminate the jacks/switching from the problem.

If necessary, one can isolate an individual circuit block by lifting a couple cap or resistor.  The audio probe will be your best friend in this hunt, but first your EYES must be used many times to ENSURE that you assembled it correctly!       If we chase problems blindly by making assumptions, this is called "easter egging", where we HOPE to stumble across the solution.  But it is usually faster to follow a firm method.    You will learn this as you go 

Thank you very much, i will keep these words in mind.

I should mention that the OC-7 circuit was built in october 2022, and worked correctly all this time, until last week. That's why I didn't think about some flaw in the building process, at first.

Many soldering pads around IC3 and IC4 are very concentrated on a small aera, i suspect that something wrong might be happening there.

I also tried to "make it worse" by moving the wires and some parts with a screwdriver during activation, but I couldn't find anything so far. I shaked the stompboxes during activation when it was working quietly, with all octaves activated, it remained quiet.

The randomness of the cracklings and the fact that they are triggered only by the Oct. Up pot, seem to point toward a dodgy part in the Octave Up section. I don't know exactly where this section starts and where it stops, but i will do some continuity tests in the aera, looking for shorts or bad solder joints.

[GibsonGM]

Use a magnifying glass    

The reason I said "pencil", and not 'screwdriver'...is because you could bridge 2 component legs with the metal screwdriver and destroy them! 

So we use a wooden rod, dowel or chopstick.   This is also called "Chop-sticking"   

[eh la bas ma]

I think i found the OC-07 issue, let's keep it between us, it's ridiculous, please don't tell anyone :

Probably some short(s) between the pcb soldering side and the back of one or several pots.

I used the black thick plastic stickers, sent by musikding, to insulate the back of the pots, but i guess it wasn't enough.

I noticed this 3 days ago, replaced them with some plastic tape and pieces of cardboard, i thought the pots were insulated, but i only found out today that it still wasn't enough.

Replaced everything again by pieces of solid plastic, fully covering the back of the pots, and it sounds like all issues are fixed.

Lots of time anf efforts spent for one very simple problem :

I changed the 3PDT, DC power jack, all electro caps, all transistors, all ICs, for the first time i cleaned the pcb with soldering residue cleaner,  struggled with an audio probe, perfomed dozens of continuity tests, scratched my head while looking at the schematics... I am almost desappointed that my issue wasn't more serious.

I must admit that I probably did not choose the best path to debugg this circuit. The troubleshooting method wasn't very tight and firm, and unfortunately i paid the price...

After 3 or 4 days on this circuit, I almost can't believe it's fixed... Let's hope this is real.

Be that as it may, I give you all my thanks for your help !

[GibsonGM]

You are welcome   This is all part of the process - I'm sure you learned something from it! In the end, YOU found the problem!

Parts are ALMOST never bad from the supplier, altho it does happen, or you may have a counterfeit IC or something.   The mistakes are almost always build errors or putting components in the wrong place.   Reading the "Debugging" thread is helpful, and also going through the 'process' the forum members have laid out can save a lot of time!   

Next time, maybe set up the 'test rig' using jumpers, if the circuit allows you to.  Many kits require the stomp switch before the circuit will work, and they prevent the 'pre-switch, pre-jack' testing.     In this case, it may not have been possible to prevent the problem, but next time you will be aware that it can happen, so you will act accordingly before fully assembling

[antonis]

I used the black thick plastic stickers, sent by musikding, to insulate the back of the pots, but i guess it wasn't enough.

Justin, that calls for sharp/pointed solder joints and/or items uncut leads of significant length..
(incidental to the event of very tight enclosing..)

[eh la bas ma]

I used the black thick plastic stickers, sent by musikding, to insulate the back of the pots, but i guess it wasn't enough.

Justin, that calls for sharp/pointed solder joints and/or items uncut leads of significant length..
(incidental to the event of very tight enclosing..)

I never had any issues with these so far, but OC-07 is the tightest build I've ever done.

Delyk's idea was to adapt Madbean's OC-07 clone for 1590B instead of BB. With that much soldering pads under each pots, the risks are higher, and some better insulating materials are surely necessary.

I don't like all those pots going to Vref...

^  I thought I was alone on that....why do they all go to Vref? That's putting DC on those pots. It seems like a design flaw, from my POV.

I thought OC-07 was a brilliant piece of engineering, among the best analog octaver, with lots and lots of other octaver circuits based on this legendary classic design ?

[GibsonGM]

I could not say how 'good' it is.  The only octaves I ever work with are things like the Octavia, which is extremely grungy, and within my recording software, LOL.

The fact that you found a mistake and the pots on longer have an issue suggest that their grounding them to Vref was not some 'fatal flaw'!