DOD fx30-B debugging.

Started by Bipolar Joe, July 09, 2014, 11:30:54 AM

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Bipolar Joe

Bought a not-completely-working DOD Gate / Loop, and trying to get it working. I'm not entirely sure what I'm doing, so after watching a bunch of videos (Thanks, Chromesphere) I took the voltages of the three ICs and the five transistors, based on this schematic.

U2 - LM358N

1 - 4.54
2 - 4.55
3 - 4.53
4 - 0
5 - 0.35
6 - 8.20
7 - 0.01
8 - 8.95

U1 - LF353N

1 - 4.51
2 - 4.51
3 - 4.27
4 - 0
5 - 4.48
6 - 4.49
7 - 4.49
8 - 8.88

U3 - MC14007UBCP

1  - 8.73
2  - 8.74
3  - 0
4  - 0
5  - 8.67
6  - 8.64
7  - 0
8  - 0
9  - 4.24
10 - 7.79
11 - 0
12 - 7.72
13 - 0
14 - 8.42

Q1 - J113

G - 0.04
S - 4.46
D - 4.47

Q2 - 2n5088

E - 0
B - 0
C - 6.41

Q3 - 2n5088

E - 0
B - 0.60
C - 0.04

Q4 - 2n5088

E - 3.24
B - 3.63
C - 8.22

Q5 - J113

G - -0.11
S - 4.19
D - 4.19

I don't really know what to look for, or if these readings hold some sort of magical key telling me what, if anything, is busted. Could anyone lend a bit of a hand, please? I'm not sure where to really go from here. Thanks!

Mark Hammer

This drawing/article shows you the role that the 4007, J113, and a couple of other transistors play in the circuit: http://hammer.ampage.org/files/dodswitch.gif

Note that the FX-30 uses a send/receive loop.  Are you sure you're using it right?

Bipolar Joe

#2
I'm positive. It's hard to describe the problem, but I think it's to do with the Sensitivity. I was trying to gate the loop. The gate opens when the knob is nearly all the way down, and after a certain point (Around 8 o'clock) it closes and just does nothing. No amount of volume will open the gate.

I'm still quite new to this stuff, so when it wasn't something obvious, I just got pretty much lost.

EDIT: Messed up the Q1 readings, proper readings put in.

duck_arse

"forbidden"! so the link says. your's is the grey one, yes?

the voltages around pins 5/6/7 of lm358 are way off, I think. check that delay pot real close.
don't make me draw another line.