Sprinkle Drive -- Low Output, etc.

Started by pbrommer, March 14, 2006, 02:56:17 PM

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pbrommer

Hello. I need a wee bit o' help. I have been trying to debug this sprinkle drive for 2 days and haven't managed to solve anything.
Originally, it would cut out when the circuit board would be moved to a certain area. Well, I redid all the wiring and haven't solved anything. Right now, it has a very low output, though the controls work for the most part. Here's the voltages, etc.

That's the procedure.

Here is the checklist to fill out:
1.What does it do, not do, and sound like? = very low output. circuit board cuts out or changes volume when moved or twisted
2.Name of the circuit = Sprinkle Drive
3.Source of the circuit (URL of schematic or project) =
Layout (.pdf layout): http://www.freewebs.com/loudnoise/Sprinkledrive.pdf
Schematic: http://happybob.com/rstrand/doodoo.gif

4.Any modifications to the circuit? None

Voltages:
Source voltage: 8.91V
Q1 (2n5457)
C = 8.93
B = 5.30
E = 0.00

U1: (TL072)
P1= 4.46
P2= 4.46
P3= 4.05
P4= 0.00
P5= 4.05
P6= 4.45
P7= 4.46
P8= 8.91

D1
A  = 0.00
K  = -0.05

D2
A = -0.05
K = 0.00

I do get quite a bit more output when I press down with my finger across lugs 2 and 3 of the clean potentiometer. Any help you can give would be greatly appreciated. Sorry, no access to a digital camera (haven't got that far with spending, seeing as I have a wedding coming up).

Patrick

-edited for less reading-
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pbrommer

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deadsnake

QuoteI do get quite a bit more output when I press down with my finger across lugs 2 and 3 of the clean potentiometer
'

This happens because you are "shorting" (lowering the resistance of the pot with your finguer). That's normal I guess. Try turning the pot all the way to each side and do the same thing. Check if it does the same thing. As you turn, let's say right, and you touch it, it should either give you more output or have no change on the output itself not the sound this creates. They shouldn't do this all either way you turn.

I had a really wierd PCB once, it would work fine and if I slaped it it would not work, so I had to heat all the solder joints (because I didn't figure out the one that was bad or cold. My solution was to make another PCB because that one was damaged. The other one worked "right out of the box". Since you got the project from tonepad, take a look ate the build reports on the bottom of the page. Some people might have the problem and found the solution. ;)

I'm not sure but I think you shouldn't be getting a 0V on the emmiter of you transistor.

pbrommer

QuoteThis happens because you are "shorting" (lowering the resistance of the pot with your finguer). That's normal I guess. Try turning the pot all the way to each side and do the same thing. Check if it does the same thing. As you turn, let's say right, and you touch it, it should either give you more output or have no change on the output itself not the sound this creates. They shouldn't do this all either way you turn..

This seems to not effect the overall volume. The clean blend just increases as I turn the potentiometer up. The control blends back in the clean signal.

QuoteI'm not sure but I think you shouldn't be getting a 0V on the emmiter of you transistor.

The confusing thing is that it is a 2n5457 FET. Perhaps it could be bad.
Thanks for some ideas. I might just let this one sit for a while.

Patrick
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