Troubleshooting Ian Fritz AD/AR

agustindead · Posted: Sun May 01, 2016 3:57 pm Post subject: Troubleshooting Ian Fritz AD/AR

Hi! I'm looking for some help with this build... I've built a dual Ian Fritz AD/AR as per Bugbrand's layout (http://electro-music.com/forum/phpbb-files/fritzdualadar_builddoc_283.pdf) with a small modification leaving out the "long" and "truncate" switches (with their associated capacitor and two diodes) and adding an eurorack power connector. I'm attaching the modified PCB.

What happens is the following: if I trigger any of the envelopes, I get just a pulse out, as if both pots were always at minimum, regardless of the settings. The only way I can get it working is if I use VERY high resistances to control attack and decay times... I discovered this by accident, gently touching the wires going to the pots and using my own skin as a variable resistance. (This sounds pretty cool for a live act, yes, but I'd rather be able to use the module normally as well... Laughing

)

It happens exactly the same with both halves, so I'm assuming it has something to do with the power supply, component choice or my layout. Sadly, I've check everything at least thrice and can't find anything... So, if someone more experienced could tell me where to look, I'd be pretty grateful.

I'm using 4148's for the diodes and I've checked with a couple of op-amps with no luck...

Thanks in advance!

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Cfish · Joined: Feb 24, 2016 Posts: 477 Location: Indiana

If it's happening on both sides, I would check each rail voltage to ground at the opamps first thing. I test with all opamps removed from the pin sockets so I don't slip and let the magic smoke out.

agustindead · Posted: Sun May 01, 2016 10:32 pm Post subject:

Thanks for the quick reply! I'm getting full +/-12v at both op-amps. Confused

Any other ideas?

Grumble

agustindead

Grumble · Posted: Tue May 03, 2016 1:25 am Post subject:

Ok, tried to figure out the design, especially what the diodes do, but I couldn't Embarassed

wackelpeter · Posted: Tue May 03, 2016 11:06 am Post subject:

could it be that the electrolytics that charge and discharge the envelope voltage out are reversed or missing ground connection?

roglok · Joined: Aug 28, 2010 Posts: 202 Location: uptown

wackelpeter · Posted: Sat May 07, 2016 10:03 am Post subject:

agustindead · Posted: Tue May 10, 2016 6:08 pm Post subject:

Sorry guys, I didn't get notified about these last replies and only saw them when I came to post a little audio clip of the really-really short times I'm getting.

agustindead · Posted: Tue May 10, 2016 6:44 pm Post subject:

Aaaaaaand it works! Is there a way to describe the pleasure of adding a new working module to your synth??

Thanks guys!! wackelpeter and roglok you nailed perfectly!