Working - sort of!
Moderators: altitude, adafruit_support_bill, adafruit, hamburgers, phono

Please be positive and constructive with your questions and comments.

Working - sort of!

by Guest on Thu Jun 23, 2005 8:09 pm

My env mod has the opposite effect to my 303, on the 303 increasing env mod opens filter on x0x it closes. Also decay has little or no effect and accent knob does nothing. HELP!

Seems quiet around here lately?

by Guest on Fri Jun 24, 2005 2:04 pm

all of the problems are probably due to the same source
your envelope generator is shorted to ground
measure the resistance between pin1 of ic12 and ground
it should be 60k or greater

trace the envelope path backwards
1. pin1 of ic12 should make a short spike of 8 - 10 volts and decay back down
2. where r138 and r152 come together should also have a spike and decay
3. where r151 and d37 come together should just be a short spike of 12 volts

it is possible that q39 is bad or in backwards
you could try replacing it with a 10k resistor and see if there is any improvement

by Guest on Fri Jun 24, 2005 2:19 pm

if you have a diode check on your meter
you should check d26 and d37
if either of these is bad the envelope wont work
if you dont have a diode check meter
set your meter to resistance and measure the resistance across
the diodes in both directions
one should be high and the other direction should be shorted

check the voltage where r152 and r138 come together
it should be 5.4 volts here with the synth on but not playing notes

by Guest on Fri Jun 24, 2005 5:56 pm

:D Thanks a lot, got it sussed it was D37 in backwards! I'm sure I double checked everything, guess thats why they say TRIPLE check huh? LOL
Unfortunately though I have damaged VR6 with my soldering iron :cry: Can I get a replacement from Ladyada?

by adafruit on Fri Jun 24, 2005 6:55 pm

i dont sell replacements, but you can buy it yerself! VR6 is part # 317-2102-1M from Mouser.com
i think they dont have a minimum order. great that youve got stuff working!

Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm
Location: nyc

Please be positive and constructive with your questions and comments.