Pork Barrell 2019 Help (Less Volume)!

[mickey.bellinello]

Hi to All!
I've got a problem with my new Pork Barrell pedal.
I tried it and acting the blend pot I've got only the dry sound no FX sound.
I use my multimeter to check voltage. All seems right except the IC 2 (MN3007). I read 0.6 and 0.7 at pin 7 and 8 instead of 4.7 as reference.
Fake MN3007??? What do I check to find what's wrong?
Thanks SO MUCH!

[madbean]

Do you have the jumpers set correctly?
Have you audio probed the input and output of the MN3007 to check for signal?

[mickey.bellinello]

Thanks for your reply!
The jumpers are correct for the MN3007. I audio probed pin3 of the mn3007 and here there is signal.
no signal on output 1 and output 2 of the ic.
Thanks

[mickey.bellinello]

As said, I probe audio, pin 3 at MN3007 is ok, no signal on output 1 & 2.
I report all the measurement:

IC 1:
Pin 1:4.33
Pin 2:4.34
Pin 3:4.33
Pin 4:0
Pin 5:4.33
Pin 6:4.34
Pin 7:4.33
Pin 8:9.10

IC 2:
Pin 1:8.10
Pin 2:4.16
Pin 3:3.50
Pin 4:0.793
Pin 5:0
Pin 6:3.83
Pin 7:0.610
Pin 8:0.610

IC 3:
Pin 1:8.12
Pin 2:3.83
Pin 3:0
Pin 4:4.16
Pin 5: varies
Pin 6: varies
Pin 7: varies
Pin 8:0.796

IC 4:
Pin 1:varies
Pin 2:4.55
Pin 3:varies
Pin 4:0
Pin 5:4.53
Pin 6:4.60
Pin 7:varies
Pin 8:9.10

Q1:
E:3.53
B:3.86
C:9.10

Q2:
E:3.68
B:4.18
C:9.10

Q3:
E:3.59
B:3.96
C:9.10

Q4:
E:varies
B:varies
C:8.12

Q5:
E:0
B:varies
C:varies



I've redone all the soldering joint and checked for bridges.. same situation

Any Ideas?
Thanks

[madbean]

Well, there's nothing alarming about your voltages. Your Vgg voltage is slightly higher than mine (0.73v vs. 0.6) but that is a completely normal range.

Obviously, the problem lies in the two outputs as you already know. You should have about 4.5v or so whereas you have less than a volt. You appear to have 56k on R20 as expected. And I assume you have twidled the Bias trimmer and no output no matter what.

First questions are always where did you source your MN3101 and MN3007. I think your 3101 is probably fine since it is putting out the right voltages. The MN3007 could be a problem (although by outward appearances it looks legit to me).

The other thing I would do is pop out IC2 and use a continuity checker to make sure pins 7 and 8 do not have continuity with any other pins on that socket, nor ground (do this with no power applied to PCB). If you look at the trace diagram in the doc you can see where you should only have continuity with C13 and R20.

Lemme know what you find.

[mickey.bellinello]

Thanks so much for your help!

I bought the mn3101 and the mn3007 from a supplier on eBay, I made a lot of order from them and never an issue.

I've got another tested mn3101 and I tried with it, same situation.
I checked the continuity and all is ok.

I ordered another mn3007, when it will arrive il update you.

Thanks again.

[mickey.bellinello]

Here I am!

I solved the problem! I received this morning a brand new mn3007 and now all works well!
Probably a fake or a defective unit again!

Thanks for the support! Really!

[mickey.bellinello]

glad you got it going. fake or rubbish IC's are the bane of my life!

I understand well! Got problems with an Aquaboy build... fake mn3101!
Hope to be a little bit lucky next times

[mickey.bellinello]

Hi to all!

As said the chorus is now working!

I made some test and I found that I have a little drop in volume when the chorus is engaged.
Any ideas to solve the problem???

Thanks