Pork Barrel 2019 - clean signal, no chorus

[slowpogo]

Hello!  After building a madbean Total Recall that actually worked straight away (build report coming), I'm ironically having issues with the much simpler Pork Barrel 2019. I just built it with the MN3007 BBD with zener selected for 12V operation.  It passes a clean signal, but I get no chorus.  With the bias trimmer I get no signal near full CCW, then clean signal which distorts near fully CW.  The tone gets darker toward the middle of the blend knob, then a little brighter on either end.  The power LED turns on, and the LFO LED pulses as you'd expect along with the rate knob.  The LFO also keeps pulsing as long as power is plugged in, even if the pedal is off -- not sure if that's normal.  It's wired to a stomp switch and input/output jacks and I've triple-checked the wiring.

I did check the other active Pork Barrel thread which has a similar issue, as well as several other threads on the Pork Barrel.  I know ICs are often the issue. The MN3007 is from Small Bear so chances are it's fine, but even they have been burned before, so I ordered a used/tested MN3007 from a good seller on Reverb to try, should have later this week. I have two MN3101s to try.  One I pulled from an old working DOD delay, so it has to be authentic; the other I got was advertised as a used pull that tested perfectly from the Florida ebay seller Dalbani (seems legit).  Both of them produce very similar voltages and no chorus.

The jumpers are correct for MN3007.  All oriented parts are correctly oriented.  You will see some styrene caps which are axial and have long leads, but I've made sure the leads are nowhere near touching other pads or leads.  I looked closely at all the pads top and bottom (inc under the pots) and can't see anything that looks like a bad joint or solder bridge. I'm very painstaking about both ordering parts and installing them, triple checking at every step, so I would be very surprised if there is a wrong part, although I admit it's possible and haven't had time to pull out a color chart and check that yet.

Here are some pics and voltages.  I can't compare voltages directly to the Pork Barrel PDF because I'm using 12V supply and that uses 9V, but they seem to be proportionally similar to the 9V voltages.  I normally use the plastic pot covers from Small Bear but this project was too tight for those, so I put electrical tape on the pots.

11.85V from Truetone Onespot, Pork Barrel bias trimmer set in the middle:

MN3101
1. 11.24
2. 5.67
3. 0.0
4. 5.71
5. 0.38
6. 10.0
7. 2.51
8. 0.75

MN3007
1. 11.24
2. 5.71
3. 4.91
4. 0.75
5. 0.0
6. 5.67
7. 4.19
8. 4.19

JRC4558
1. 5.61
2. 5.62
3. 5.58
4. 0.0
5. 5.6
6. 5.61
7. 5.61
8. 11.54

TL062
1. ~ wide range
2. ~ 5.75-5.82
3. ~ wide
4. 0.0
5. ~ 5.75-5.82
6. ~ 5.75-5.82
7. ~ wide
8. 11.55

Q1
1. 4.65
2. 5.01
3. 11.55

Q2
1. 4.92
2. 5.43
3. 11.55

Q3
1. 4.73
2. 5.14
3. 11.55

Q4
1. -0.1
2. -0.12
3. 11.25

Q5
1. 0.0
2. 0.42
3. 9.18

[Scruffie]

Q4.

[slowpogo]

Thank you. The build PDF just says "varies" for 1 and 2 of Q4. I thought the negative voltage might be weird but wasn't sure.

I have extra 2N5088s and can try a different one later today.

[slowpogo]

I tried a new 2N5088, no change. Went backward through the schematic and discovered there was no continuity between R34 and C20.  Strange, they both looked like nice shiny joints.  Reflowed them both, and bam, it works!  I was surprised at the brevity of Scruffie's response, but I guess "Q4" is all I needed.  Thank you!

It sounds pretty good, but surprisingly warm/lo-fi.  Even with my tele bridge pickup, it takes away a lot of the chime and sounds mellow.  Is that consistent with others' experience? Maybe the carbon comp resistors contribute to that?

Disregard, in my excitement I forgot about the bias trimmer.  Turned CW a bit and the sound got a lot more balanced.  Sounds great!

[Willybomb]

Thanks for this thread.

I've built 3 Porkbarrels now, and the third one is intermittent.  Sometimes it works fine, sometimes it will only pass clean signal...  I can't seem to get it to replicate reliably (it won't work at praco, get home, plug in... and it works), so I'll check Q4 in particular and see that fixes things.

[Scruffie]

I tried a new 2N5088, no change. Went backward through the schematic and discovered there was no continuity between R34 and C20.  Strange, they both looked like nice shiny joints.  Reflowed them both, and bam, it works!  I was surprised at the brevity of Scruffie's response, but I guess "Q4" is all I needed.  Thank you!

It sounds pretty good, but surprisingly warm/lo-fi.  Even with my tele bridge pickup, it takes away a lot of the chime and sounds mellow.  Is that consistent with others' experience? Maybe the carbon comp resistors contribute to that?

Disregard, in my excitement I forgot about the bias trimmer.  Turned CW a bit and the sound got a lot more balanced.  Sounds great!

Apologies, I was busy at the time and thought some help was better than waiting

It's a buffer for the LFO so yeah, it should have had the LFO voltage on the base of it hence I knew it was the problem.

Glad you got it working.

Thanks for this thread.

I've built 3 Porkbarrels now, and the third one is intermittent.  Sometimes it works fine, sometimes it will only pass clean signal...  I can't seem to get it to replicate reliably (it won't work at praco, get home, plug in... and it works), so I'll check Q4 in particular and see that fixes things.

Sounds like you need to compare voltages at home and practice to find the culprit.

[Willybomb]

Sounds like you need to compare voltages at home and practice to find the culprit.

Yeah, I'm pretty slack that way.