Bananalogue VCS diy board set available

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

do you think the vcs differs much from the envylope?

zthee · Joined: Feb 20, 2008 Posts: 414 Location: Stockholm

sduck · Posted: Sun Feb 08, 2009 9:01 pm Post subject:

So I just finished up building this motm format version. Seems to work ok - all the pots and jacks do things, although I'm not familiar enough with the thing to know for sure if they're doing the right things.

The led doesn't work. And I was getting this weird behavior on the fall of the slope where it would dip below zero and then rise back to zero. Upon staring at the pcb enough it looked like the led wires might be labeled backwards, so I switched the wires. The led still doesn't work (I checked the led - it's functional), but the weird end of cycle behavior is gone. So perhaps I just have a wrong led type.

Fun unit - I hooked up all the patches as described on the old bananalogue page to test it, and they all work as described. The knobs are really touchy - there's some pretty big range on these things.

andrewF · Posted: Sun Feb 08, 2009 11:32 pm Post subject:

I haven't seen this PCB, but if all the outputs work and just the LEd doesn't, the problem can't be too hard to sort.
would the transistor/diode/resistor near the LED holes be a LED driver subcct?
maybe it is something like Ken's LED driver PCB
Posted Image, might have been reduced in size. Click Image to view fullscreen.

edit
just found this image on P2 of this thread
Posted Image, might have been reduced in size. Click Image to view fullscreen.

it looks like the LED A&K markings are reversed. The led's cathode 'K' should go to the 1k resistor.
Also the hole marked 'K' should not be connected to 0V, that track should be cut and a connection made to +12V

this is just guesswork from looking at the PCB and Ken's led-driver. hope this doesn't blow it up

sduck · Posted: Mon Feb 09, 2009 7:28 am Post subject:

That fixed it! I had already switched the wires, so cutting the anode wire from the led and running a wire from a 15+v rail to the cut worked. 100% working now! Thanks!

creatorlars · Posted: Sun Apr 12, 2009 9:25 pm Post subject:

I can confirm that I'm having an identical problem with the rise pot not working as it should -- I've double checked all my wiring and parts, everything's correct according to the board. This is pretty frustrating, with no schematics to look at. Sad

Any further developments with this, or anyone have theories? What exactly did you do to fix it? The module seems to work fine otherwise.

helitron · Joined: Feb 27, 2008 Posts: 21 Location: vienna

creatorlars · Posted: Sun Apr 12, 2009 11:41 pm Post subject:

I will try that, but won't it make the VC Rise jack/attenuator unusable? I am using banana jacks so I can't take advantage of a switched connection.

sduck · Posted: Wed Apr 15, 2009 7:11 am Post subject:

I've seen that +15v to the rise jack mentioned several times, and it sounds bogus to me. If that was the way to fix it, then you'd have a useless jack - or one with +15v hitting everything that's plugged into it. My VCS (see above) doesn't have +15v coming out of the rise jack, and it works correctly. I'm going to have to sit for a while and compare the euro pcb against my working motm pcb and see what the difference is - I'm pretty sure it's some small error in the traces.

Funky40 · Posted: Fri Apr 17, 2009 3:31 pm Post subject:

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

perhaps just ask ken
he designed the pcb and is currently working on a new VCS pcb for his CGS range so he might give you some support

TekniK · Joined: Aug 10, 2008 Posts: 1059

Okay, a demo with this VCS,with VC control of rise & fall (only one VCS in this patch)

pristak · Joined: Nov 17, 2006 Posts: 37 Location: Dallas, Texas

I just finished one of mine last night. Mine are the MOTM single board version. It was 2am so I need to put it through it's paces today once the family wakes up but I confirmed it did some of what it is supposed to do last night.

koura · Joined: Feb 02, 2009 Posts: 13 Location: chicago

TekniK · Joined: Aug 10, 2008 Posts: 1059

The board where sold to us with an error,and those asses did know it very well,now u know why no support was given!,bastards.

just do this 'debug' and it will work like it should be:

e-grad · Joined: Sep 12, 2008 Posts: 142 Location: Berlin

Thanks for sharing!

janvanvolt · Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany

I still have issues (after having +/- 15V reversed at one time). Nothing seems to work Sad

Exchanged already are all IC's and Transistors.
The "kludge" has also been applied.

Any ideas on how to debug this lovely VCS ? It's sad it does nothing.

TekniK · Joined: Aug 10, 2008 Posts: 1059

should work,re-check your wiring ,soldering and components

janvanvolt · Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany

I've got one the "original" boards from Bananalogue, so this is a bit different from the CGS version...

TekniK · Joined: Aug 10, 2008 Posts: 1059

fadeddata · Joined: Dec 27, 2004 Posts: 43 Location: Nashville TN

unit-sound, I've got one of the original's as well Smile

I had to make one additional kludge to get it to work.

Before making this change verify that ~15V is hitting the cathodes on the Trigger/End/etc board diodes. If so you have a board like mine and maybe the attached pic will help.

Seems there were many different VCs boards made. Mine had pin 4 of the LM3900 going to the cathodes of the trigger section instead of coming off zener diode which I think holds the voltage at ~5V. After fixing this and adjusting the trimmer my VCs started working!

Also make sure to cut the traces before and after the diodes (you can see in the pic)

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janvanvolt · Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany

Okay, got it sorted out. It was the Inter-PCB wiring as well as two defective 2N's

TekniK · Joined: Aug 10, 2008 Posts: 1059