Pork Barrel grounding?

[Styles]

Hello, finished my pork barrel last night and it will pass a signal but there's no chorus. Tried sweeping trimpot and no luck there. I grounded the board at the G pad between the in an out but not and the ground at the 9v- is it necessary to ground at both pads?

Thanks!!

[Bret608]

I think you may want the ground pad between the in and out pads connected to your footswitch, and the ground at the 9v area connected to your DC jack. You may want to check the Madbean wiring diagram for more clarity that I can provide. Anyway, try this and report back--I'm in the finishing stages on my Pork Barrel too, so I'll be curious to hear how it works out!

[Styles]

I'm going to try it when I get home tonight. This is actually part of a multi fx project so theres no ground from the battery or dc jack, just the common ground and 9v coming from a PSU that's powering four other boards

[mgwhit]

Either ground pad is fine.  They're both connected to the same ground plane, so there's no need to connect both.  As far as I can tell they're just there for convenience.

[DuctTapeRiot]

Can you post some nice clear pics of the top and bottom of the board, and a good description of any/all trouble shooting you have done so far?

[mgwhit]

When you say it will pass signal but there's no chorus, do you mean that it passes unchorused signal in effect mode (i.e. not bypassed)?  If so, you're certainly grounded properly -- at least in certain parts of the circuit.  I agree, pics will help, but I'd also like to see voltages from the pins of your IC's.  Which BBD chip did you use?

[Scruffie]

Voltages are better than pictures. Post them up and it should be pretty easy to spot where the issue is.

[Styles]

I used an MN3007 that I got for way cheap from a Chinese ebayer. Thinking I might have got a bootleg chip- have a legit one coming from small bear, will try with that and report back. Thanks!!

[Styles]

Hello again- been tearing my hair out over this- gone over the board multiple times, was convinced that I might have bought some bunk chips from a Chinese ebayer, shelled out $11 to small bear for a legit MN3007, and still no luck.  Will pass a signal when engaged, but no chorus effect through whole sweep of trimpot.  As always, help or guidance is much appreciated here's the debug stuff from diystompboxes:

1.What does it do, not do, and sound like?  will pass signal when engaged, though no chorus effect throughout sweep of trimpot
2.Name of the circuit = Madbean Pork Barrel, w/ MN3007/3101
3.Source of the circuit (URL of schematic or project) = http://www.madbeanpedals.com/projects/PorkBarrel/docs/PorkBarrel.pdf
4.Any modifications to the circuit? n
5.Any parts substitutions? If yes, list them. C10 8.2n, sub'd parallel 6.8 & 1.5 caps
6.Positive ground to negative ground conversion? no

IC1:

1: .01
2: 2.92
3: 0
4: 0
5: 2.9
6: 0.1
7: 2.9
8: 8.9

IC2:

1: ~
2: 4.49
3: ~
4: .01
5: 4.51
6: 4.51
7: 3.5
8: 9.04

IC3:

1: 1.39
2: 1.38
3: 0.01
4: 0.01
5: 0.1
6: 0.86
7: 0.01
8: 0.6

IC4:

1: 1.39
2: 0
3: 2.01
4: 0.1
5: 1.31
6: 1.31
7: 1.38
8: .01

Q1:

c: 9.04
b: 1.87
e: 2.86

Q2:

c: 9.04
b: 2.52
e: 2.24

Q3:

c: 9.03
b: ?
e: 2.21

Q4:

c: .55
b: .58
e: .01

Q5:

c: 1.38
b: 1.93
e: 0.1

D1:

a: .86
k: .55

D2:

a: .68
k: .86

D3:

a: 0
k: 9.04

[mgwhit]

I just measured the pins of all of my IC's and your IC2 values look similar to mine, but your values on IC1, IC3 and IC4 all look low.  I'm gonna go eat some dinner and watch the Derby, and then I'll review the schematic and see what I can make of this.  Thanks for posting voltages.  We'll get this.

[mgwhit]

Let's start with the voltages on IC1 (the 4558), since I think it's the simplest to tackle.  You should be getting your (9V) input voltage directly on pin 8 (looks like you do), 0V (ground) on pin 4 (again, good) and your VB reference voltage on pins 1-3 and 5-7.  That's where it starts to look crazy.

Some of your pins have 2.9V, which is probably your VB reference voltage (depending on the setting of your trimmer).  See if you can move your trimmer closer to the middle setting and get close to 4.5V there.  Now the fact that you have 0V (or close enough) on pins 1,3 and 6 concerns me (a.) because that's the wrong value for those pins, and (b.) if you're getting dry signal through the effect that IC has to be working.  Can you please triple check those pin voltages on IC1?  Also, please check that your R40 is 33R and not 33K or some other (high) value.

[Styles]

Can you please triple check those pin voltages on IC1?  Also, please check that your R40 is 33R and not 33K or some other (high) value.

That was it!!  I didn't have a 33R, so grabbed a 20R and a mislabeled 15K.  Thank you so much!!!!!!!  Chorus works great now!

[mgwhit]

Excellent!  I love this Chorus.  I spent a good deal of time playing with it again last night after taking readings.  I really need to get it boxed -- I have the enclosure drilled, but I'm having trouble with the art work (not my forte).  Have fun!