Wavefolder dead. ANy hint?

[gibrancurtiss]

Hi Guys.

Finished the Yusynth Wavefolder.
After calibrating the trimmers I checked the entire circuit and here what i got:
-everything is perfect until the wave reaches pin9 U1c.
-pin 10 is grounded.
-but , a 13V rises from pin8 U1c

After this point no more wave.
Already replaced U1 by another TL or LM but still the same.

Any hint why U1c did not invert the signal ?
All red area is "dead". There is voltage but the wave didnt reach it.


Thank you and have a nice week!

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[micromusic]

With all my Yusynth projects when they don't work it's normally a short or a badly etched board or a dry joint or the wrong value component so quite a few things to
check
Make sure all the above are ok as these circuits do work if you use all the listed components
I assume you have checked for power on all the chips etc as that's another thing to test

[micromusic]

Check you have diodes 1 and 2 in the right way as I am stuffing this board right now and had to check the schematic for the correct orientation

[micromusic]

Just finished mine tonight
Worked first time and needed no trimming/setup (lucky I guess)

[gibrancurtiss]

Hi Micromusic

I've found the error.
One thing that i 've never see before.
The R2 100k had only 120ohms.
Even with right colors code.

Just replaced the resistor

Thanks

[micromusic]

That's a frustrating thing to find🤒 I had a similar issue with a strip of 50 100K resistors that turned out to be 1K
I have posted a YouTube video of mine just Google Yusynth wavefolder mines the one with the white panel one side is the Metalizer the other half the wavefolder

[gibrancurtiss]

Great module.

Worth to build it

[yusynth]

Don't forget Jurguen Haible for the original design. My contribution was to add a VCA to drive the input signal and design a proper PCB.

[bonzai]

d'oh!
Thanks guys for the resistors hint, that just didn't come to mind. I was having the same problem: the 15k and 10k were 15 and 10 ohms (grabbed the wrong bag apparently - still not used to these blue MF resistors...) Swapped 'em out, works.

by the way, for a noob: how important is the transistor- and diode matching and what would be the effect if they were not matched?
I just got a whole bunch of diodes from the same batch (on a belt), not sure about the transistors though (but they all came in the same bag), and matching these doesn't sound like the fun part at all.

Cheers,
bonzai

[yusynth]

The matching here is only meaningful if you want to obtain a perfectly symmetrical signal on the output. I you don't care about symetry then don't bother matching components.

[bonzai]

Ah, okay! It already looked quite symmetrical to me on the scope, so I guess there is no real need for matching (at least for me).

Thanks!