No clipping on Kliche Mini

apierz

Member
I've got a Kliche mini that isn't clipping. As I turn the gain knob I get changes in volume and it sounds like it is mixing two channels, but they are both clean, even with the gain turned all the way up. I get sound when the pedal is on and when it's off and the treble knob and volume pot seem to be working.

The issue seems similar to the one in this thread:

so I've tried the advice there.

1. Tested for continuity using these charts and got continuity on all of them:

Kliche Mini Continuity Test.jpg 1658508021991.png

2. Did my best to verify all component values.
3. Changed out the TL072 ICs
4. Tested forward voltage on GE diodes: (.323 and .313)

I've also tried an audio probe but since I get signal all the way through I'm not sure how to pin down the problem. Here's some pictures of the board, any advice would be appreciated.
Image-1 - Copy.jpeg Image-2 - Copy.jpeg

Image.jpeg Image-3 - Copy.jpeg
 

Dirty_Boogie

Well-known member
I'd start by cleaning the board. Blow off both the top and bottom with a can of compressed air. Then use a toothbrush and some isopropyl alcohol to clean the solder side. The look for any solder issues, like solder bridges. After that, the detailed troubleshooting can begin.

Are these solder bridges?
Image 21.png

Is that a hair or a strand of wire across the TL072?


Image 22.png
 

apierz

Member
Did you use the footswitch board? Pin 4 of the FS taps directly at the clipping diodes, so I'd check that out.
Thank you for the suggestion. Yes, I did use the included footswitch board. I tested continuity on each wire between the main board and the footswitch board and got a tone on the DMM for each of them so it looks like the footswitch is properly connected at least.
 
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swyse

Well-known member
I tried to assist in the other post with the similar issue, but I ran out of ideas. I'm not sure what the issue could be. I notice you used the same exact diodes, so my only suggestion is trying different diodes even though yours test good. I personally would just tack some schottkys to the bottom of the pcb to test quickly because I hate desoldering, especially fragile parts.
 

MichaelW

Well-known member
Wait, are you saying you get no clipping at all? Or no diode clipping? The OpAmp should clipping and giving you overdrive sound, the diodes just add a little flavoring on top. (albeit very mythical and mystical flavoring).

If your getting nothing but clean gain then there's something else going on besides the diodes.
 

apierz

Member
Yeah it seems like nothing is happening on the “gain” side of the mix and turning the drive knob counterclockwise makes it louder which is leading me to think the problem is at least partially in or more of the op-amps. Wouldn’t be the first time I wrecked an IC.

I needed more TL072s for something else so when they arrive I’ll be able to swap out the ones I have with parts from a different batch.

If that doesn’t make a difference I can start probing through the gain section to see if I can figure out where it’s going wrong. I should have some other Ge and schotky diodes I can also try to swap in if necessary so hopefully I can report back in a few days.

Thanks again for looking at this.
 

fig

Village Idiot
You could swap the TL072s (IC1 with IC2) and see if that makes a difference..or if you have any other dual op-amps you can try one. (y)

Edit: See below. 👇
 
Last edited:

Coda

Well-known member
Make sure your dual-gang pot is SUPER insulated. My Klon did the same thing as yours for a year before I was able to get it to work properly. I ended up essentially wrapping the entire dual-gang pot in electrical tape…
 

music6000

Well-known member
Yeah it seems like nothing is happening on the “gain” side of the mix and turning the drive knob counterclockwise makes it louder which is leading me to think the problem is at least partially in or more of the op-amps. Wouldn’t be the first time I wrecked an IC.

I needed more TL072s for something else so when they arrive I’ll be able to swap out the ones I have with parts from a different batch.

If that doesn’t make a difference I can start probing through the gain section to see if I can figure out where it’s going wrong. I should have some other Ge and schotky diodes I can also try to swap in if necessary so hopefully I can report back in a few days.

Thanks again for looking at this.
You need to respond or we can't help you!
You viewed this yesterday since requests to you were asked?!
 

apierz

Member
Here are the voltages I recorded off the ICs starting from the one closest to the jacks and going down towards the footswitch. Pins are numbered starting with top left and going counterclockwise.

IC1:

1. 8.89
2. 4.66
3. .004
4. 4.03
5. 8.38
6. 3.98
7. 5.49
8. 8.88

IC2:

1. 4.45
2. 4.47
3. 4.46
4. 8.40
5. 4.46
6. 4.46
7. 4.48
8. 15.86

IC3:

1. 4.47
2. 4.47
3. 3.52
4. 0.001
5. 4.47
6. 4.47
7. 4.47
8. 8.88

When I tried the audio probe on the diodes I don't notice any clipping. I also tried insulating the dual gang pot with silicon tape but that didn't make a difference. When I measured C8 I got 440pF and C14 770pF.
 

music6000

Well-known member
IC2 - 4 should be -8.40V
Can you remove IC2 & test for continuity between pins 1 & 2, 2 & 3, 3 & 4, 4 & 5, 5 & 6, 6 & 7, 7 & 8, 8 & 1 .
 
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apierz

Member
IC2 - 4 should be -8.40V
Can you remove IC2 & test for continuity between pins 1 & 2, 2 & 3, 3 & 4, 4 & 5, 5 & 6, 6 & 7, 7 & 8, 8 & 1 .
You are right, I misreported pin 4 on IC 2 and missed the minus sign. It is reading as -8.40v.

Continuity test results on IC2:

1&2: no
2&3: no
3&4: no
4&5: no
5&6: no
6&7: no
7&8: no
8&1: no

I did the other TL072 as well:

1&2: yes
2&3: no
3&4: no
4&5: no
5&6: no
6&7: no
7&8: no
8&1: no
 

music6000

Well-known member
You are right, I misreported pin 4 on IC 2 and missed the minus sign. It is reading as -8.40v.

Continuity test results on IC2:

1&2: no
2&3: no
3&4: no
4&5: no
5&6: no
6&7: no
7&8: no
8&1: no

I did the other TL072 as well:

1&2: yes
2&3: no
3&4: no
4&5: no
5&6: no
6&7: no
7&8: no
8&1: no
What you are experiencing happened to another Member who used the same looking red striped diodes.
I don't know if it was resolved.
Did you test the forward voltage on these Diodes, it should be around 0.27v to 0.35v for Germanium?
 
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