small stone could be the end of me - please help

Started by jmasciswannabe, March 17, 2005, 05:19:15 PM

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jmasciswannabe

All right. I have spent all day trying to get this going. I have read a lot from here and have done the following. Checked all wiring, all compnent values, resoldereed everything three times, checked for solder traces, checked pot and tried to barter with God in an attempt to get it to work properly.

The problem - effect doesn't sweep. When I move the pot from one extreme to the other I hear a slight phase sound go from top to bottom, kinda like a wah pot. I have built the effect from ggg and am using ca3094s that are new.  These are the voltage readings.

IC1
3.96
2.79
2.79
0
.66
2.87
6.99
6.99

2,3 and 4 - pretty much the same as 1 with small changes in pin1 and 6

IC5
1.8
.24
.72
0
.51
.71
7.02
.72

I measured the transistors as well

--------e-----b-------c
Q1    2.22  1.91    6.42
Q2    7.04   6.42   4.14
Q3    4.95   .73    .24
Q4    4.95   .24    1.16

Audio probing pin six on ic1, i do not hear a vibrato regardless of where i turn the pot. Pin 5's of the first four ic's voltage changes with the pot between .65 - .69

Can anyone offer some sugestions on what else to look for or check or do?

The schematic and layout:
http://www.generalguitargadgets.com/diagrams/smallssc.gif
http://www.generalguitargadgets.com/diagrams/smallspl.gif

Thanks
Ian
....the staircase had one too many steps

jmasciswannabe

....the staircase had one too many steps

dr

....have you checked the orientation of the IC's,checked all the legs to see if any are bent and making solid and not intermittent contact?....I have built this one twice (for my own "stereo version") and I think I ended up with a quite few dumb things like that with both of them; I had a couple things like an open in the copper trace, a shorted copper trace, about three faulty or cold solder joints(I use liquid flux every time now along with the solder-sometimes there doesn't seem to be enough flux in the solder)..I think I even had wires going to a couple of wrong spots-and this was after swearing I'd checked everything was OK six or seven times.....doesn't hurt to walk away and rest the eyes awhile-sometimes our eyes will lie to us....simple continuity checks to all the traces might sound mundane, but you may be surprised-I gave up at least ten times until I eventually fixed only five problems....don't give up on it,though- I absolutely love mine now that it's totally working and have modded it to death-it's a killer effect when it gets going..do you think you can post a pic of both sides?that may be a help in case some extra eyes can help you....I also used the same GGG board layout,and I can tell you it does work well!.........dr

dr

....just thought of another thing that may be causing the problem-did you connect up all three pot wires or only two?.....

jmasciswannabe

sorry it took a bit to reply, dr. I have all three wires going to the pot and though the multimeter shows that ots working I am going to replace it with a new one as well as the color switch and the 3pdt switch and all the wiring. Went through with the beep function on the meter and made sure that all points on the ics and traces were connecting. At this point I am thinking about just buying a new one. Hah!
....the staircase had one too many steps

dr

....have you tried flexing the board a bit?...

dr

...more important than that, is the 3PDT switch wired correctly? that's another one that will drive you nuts!....I have wired them wrong in the past considering its so easy to do so....