Kliche mini question

[griff10672]

Regarding the Kliche mini ...
Anyone have an idea why I would have voltage on my output jack ........ I'm getting 0.513 V AC / 0.5 mV DC on my out put jack ...
and throughout the buffered bypass circuit . If I pull the TC1044SCPA out ..... the Voltage goes away ..... it seems to be only on the buffer path of the circuit ...
when I trace the circuit on my scope .... from input to output .... nothing on my input jack ... or R31 .... the voltage shows up right on the side of R1 that touches C1 and runs through the whole buffered bypass part of the circuit to my out jack .
I'm assuming that's what's destroying my bypassed tone and causing some weird buzzing on the end of played notes / chords
When I trace my Kliche OD none of this happens .... zero voltage ... bypassed my signal is fine if not sounding better due to the buffer working correctly I'm assuming .
literally the only difference in the two are that I didn't use a Footswitch board on my Kliche OD .... I wired the footswitch direct to the main board .
all the parts are the same ........

 

[Cybercow]

I found weird buzzing at the end of notes in a Klon circuit is the usually the result of bad opamps. Specifically TL072CP dual opamps. I did a short run of 5 Kliche builds for a client and ALL of them exhibited that "weird buzzing at the end of notes" issue. I spent a couple hours troubleshooting, including swapping opamps, and when I hit a batch of TL072 chips that didn't exhibit that issue, I started looking at the date codes and testing every TL072 I had in stock. I had a few from SmallBear, a couple from StompBoxParts, and a few dozen from Tayda. Every one from both SmallBear and StompBoxParts worked fine and were either TL072CP or TL072IP - and none of them had the same dates codes as the dozens I had from Tayda. Every TL072CP I had from Tayda presented that same "weird buzzing at the end of notes" issue. I recorded the date codes from them.

I found three bad batches of TL072CP opamps from Tayda . . . .

18MDSHY​

14AP8NM​

07A5L8QM​

Bottom-line: when I used TL072IP devices from StompBoxParts or SmallBear and swapped out the TL072CPs, that "weird buzzing at the end of notes" went away. At least, based on your description, that's what worked for me. Check the date codes on the opamps and record it please. And please let us know what you find.

 

[griff10672]

I found weird buzzing at the end of notes in a Klon circuit is the usually the result of bad opamps. Specifically TL072CP dual opamps. I did a short run of 5 Kliche builds for a client and ALL of them exhibited that "weird buzzing at the end of notes" issue. I spent a couple hours troubleshooting, including swapping opamps, and when I hit a batch of TL072 chips that didn't exhibit that issue, I started looking at the date codes and testing every TL072 I had in stock. I had a few from SmallBear, a couple from StompBoxParts, and a few dozen from Tayda. Every one from both SmallBear and StompBoxParts worked fine and were either TL072CP or TL072IP - and none of them had the same dates codes as the dozens I had from Tayda. Every TL072CP I had from Tayda presented that same "weird buzzing at the end of notes" issue. I recorded the date codes from them.

I found three bad batches of TL072CP opamps from Tayda . . . .

18MDSHY​

14AP8NM​

07A5L8QM​

Bottom-line: when I used TL072IP devices from StompBoxParts or SmallBear and swapped out the TL072CPs, that "weird buzzing at the end of notes" went away. At least, based on your description, that's what worked for me. Check the date codes on the opamps and record it please. And please let us know what you find.

I won't buy IC's from Tayda ...... bought a batch of 100 from Mouser .... doesn't mean I couldn't get a bad batch from Mouser I suppose ...
Thanks for the input by the way ...... you are the first to mention having the same problem ..... I did not try to switch out the op amps .... just the charge pumps .
I have some TL72's that aren't from this recent batch ..... I will give them a try when I get home .
again ... Thanks !!!

 

[griff10672]

OK .... I don't think that's it ...... not for me anyway ..... I just swapped all the chips ... from my working perfectly Kliche OD into my Kliche mini build ... and vice versa ..
I'm getting a tiny amount of DC voltage on the outputs of both .... no AC voltage at all on the Kliche OD ..... and I'm still getting a very small amount of AC on the output of my Kliche mini ...
somehow AC is getting into my bypassed signal .
I can't sound check the swap in chips ..... only have my MM with me at the moment

 

[Cybercow]

If the "weird buzzing on the end of played notes / chords" follows the opamps, (try placing the suspected bad chips in your known working Klon) then it's the opamps. If the "weird buzzing on the end of played notes / chords" does NOT follow the opamps, then there is something wonky about the build.

Did you check the date-codes on the suspected opamps?

Some good, clear, close-up photos of the build details would be helpful at this point.

 

[griff10672]

I swapped the chips from my working Kliche OD into the Kliche mini .....
still have the weird voltage on the mini .... and the Kliche OD with none
I can't sound check any difference at the moment but I'm assuming getting the voltage on the signal is causing the problem .
none of the codes match up to what you have listed

 

[griff10672]

OK ..... so further went through the circuit with my scope ..... and found that the " treble , volume and gain still effect the signal when the pedal is off ...
any ideas what could be causing that ? cause that has to be why my bypassed signal sounds like crap ... no ??
my Kliche OD does not do this at all ...... but these Kliche minis that I've built are all doing that ... the controls still effect the signal big time ...
is there a spot in the circuit to test to see why the signal is still going through when off ??

 

[fig]

I think it's a buffered bypass...

 

[griff10672]

I think it's a buffered bypass...

yes it is .....

 

[benny_profane]

yes it is .....

That means that the input isn't grounded and the signal is switched at the output. It's normal to have audio throughout the circuit regardless of bypass.

 

[griff10672]

That means that the input isn't grounded and the signal is switched at the output. It's normal to have audio throughout the circuit regardless of bypass.

I realize this ..... but when I turn the gain or the treble or the volume it still has an effect on the bypassed signal ...
this doesn't happen on my Kliche OD .... the signal doesn't budge .....