[sdiy] Rwilson EG trouble

[Tim Parkhurst]

On 7/27/07, Scott <Scott at scottwick.com> wrote:
> Hi,
> I built Ray's E.G. here...
> http://www.musicfromouterspace.com/analogsynth/norgate_adsr_001.html
>
> and it worked fine, other than I had 2 pots wired backwards, and the
> led's in the wrong order.
>
> I corrected the mistakes, and somehow caused a new problem, and I can't
> find what is causing it.
>
> When I apply a trigger, nothing happens.
> When I apply a gate, it skips the attack, the decay works like the
> attack should, sustain and release work as they should.  Only the LED's
> for the sustain and release stages work, and the LED for the sustain
> slowly lights during the attack stage (which is actually the decay pot)
> and then stays lit during the sustain.
>
> If anyone knows where I should be looking for my trouble, I'd really
> appreciate it.  I've replaced all the IC's.  I've checked my wiring
> again and again, and just can't find the problem!
>
> thanks
>

Hi Scott,

First thing I'd check is to make 100% sure that all the diodes (ALL of
them, not just the LEDs) are oriented correctly. Most of these are
"steering" diodes and are meant to make sure current flows in the
right direction at the right times. Getting one or two of them
backwards might cause the symptoms you're describing. Also, make sure
that you don't have any bad diodes (should conduct in one direction
only). A diode failure is fairly rare, but it can happen, especially
if a small diode is overheated during soldering. Best of luck, and
hopefully you'll get the EG sorted out soon.


Tim (needs a good sorting out) Servo
-- 
"Imagination is more important than knowledge." - Albert Einstein