[HELP] MN3007 Pork Barrel didn't work :(

[slim_blues_boy]

hi, I just build a Pork Barrel, but sadly, it didn't work.
perhaps somebody can help me sort this thing out.

(1) Project Name: Madbean Pork Barrel (file ver.2)

(2) General description of the problem
only produce crackling noise

(3) Steps that you have taken to try to resolve the issue
retrace the pcb path, check the solder join, check for any short/bridging, check connections

(4) List any substitutions you used for parts/values
used same value as listed BOM

here is what I've got on voltage measurement (power supply Tonepad LM317 regulated):
IC 1 (JRC4558D)
1 = 9.11v
2 = 9.09v
3 = min 0.13v, max 0.44v (from VB trim)
4 = 0v
5 = min 0.13v, max 0.44v (from VB trim)
6 = 8.79v
7 = 8.8v
8 = 9.17v

IC 2 (TL062)
1 = 1-7.9v (fluctuating, approximately)
2 = 4.4v - 4.7v (fluctuating, approximately)
3 = 3.2v - 6.1v (fluctuating, approximately)
4 = 0v
5 = 4.4v - 4.7v (fluctuating, approximately)
6 = 4.5v - 4.7v (fluctuating, approximately)
7 = 3.3v - 6.2v (fluctuating, approximately)
8 = 9.17v

IC 3 (MN3101)
1 = 9.1v
2 = 4.63v
3 = 0v
4 = 4.66v
5 = 0.25v
6 = 8.25v
7 = 2.5v - 2.9v (fluctuating, approximately)
8 = 0.59v

IC 4 (MN3007)
1 = 9.11v
2 = 4.66v
3 = 2.5v
4 = 0.59v
5 = 0v
6 = 4.63v
7 = 2.86v
8 = 2.86v

Q1 (2N5088)
E = 7.45v
B = 8.15v
C = 9.17v

Q2 (2N5088)
E = 2.63v
B = 3.15v
C = 9.17v

Q3 (2N5088)
E = 0v
B = min 0.13v, max 0.44v (from VB trim)
C = 9.17v

Q4 (2N5088)
E = 0v
B = 0.28v
C = 8.49v

Q5 (2N5088)
E = 1v - 3.2v (fluctuating, approximately)
B = 1.7v - 3.9v (fluctuating, approximately)
C = 9.11v

anyone can help me?
I got the BBD from eBay (China/Hong Kong), fake chips perhaps?
or there are other problem?

thank you

[Scruffie]

Why does everyone always assume the worst for the BBD...

Issue is IC1, wont work like that, something is messing up the voltages on it, should have approx half supply on pins 1,2,3,5,6 & 7.

LFO & Clock seem good.

No time to dig deeper this second but your V.ref might be going wrong (measure it at lug 2 of the trim) or you orientated  the cap in for it backwards maybe... or something in its path or round IC1 is causing an issue.

[slim_blues_boy]

Why does everyone always assume the worst for the BBD...

Issue is IC1, wont work like that, something is messing up the voltages on it, should have approx half supply on pins 1,2,3,5,6 & 7.

LFO & Clock seem good.

No time to dig deeper this second but your V.ref might be going wrong (measure it at lug 2 of the trim) or you orientated  the cap in for it backwards maybe... or something in its path or round IC1 is causing an issue.

hi Scruffie, thank your for your input.
first time using BBD, so I'm not quite familiar.
the MN3101 looks different from usual MN3101 that I saw on various pics, so I thought maybe it's not genuine.
will try to look on the IC1

[Bret608]

Something else that you could do is double-check the resistor values for any resistors associated with IC1. Have a look at the schematic to see which those are. The only time I've ever had an effect with an IC not work was due to an incorrect resistor (100k instead of 1m!  )

Scruffie, which resistor(s) set the bias on IC1? That's the main thing I'm suspecting besides a possible backwards cap.

[Scruffie]

Something else that you could do is double-check the resistor values for any resistors associated with IC1. Have a look at the schematic to see which those are. The only time I've ever had an effect with an IC not work was due to an incorrect resistor (100k instead of 1m!  )

Scruffie, which resistor(s) set the bias on IC1? That's the main thing I'm suspecting besides a possible backwards cap.

The v.ref is set by the trimmer.

[slim_blues_boy]

ok, fix the problem on IC1. follow Scruffie instruction and play around the trimpot.
and finally, I can get Vref from 2v-5.5v using the trimpot.

I can get clean signal right now, but still no chorus. and went silent if I switched to vibe mode.

here is my updated voltage chart (trimpot set full clockwise):
IC 1 (JRC4558D)
1 = 5.4v
2 = 5.4v
3 = 5.4v
4 = 0v
5 = 5.4v
6 = 5.4v
7 = 5.4v
8 = 9.08v

IC 2 (TL062)
1 = 3v - 6v (fluctuating, approximately)
2 = 4.58v
3 = 3.8 - 5.2v (fluctuating, approximately)
4 = 0v
5 = 4.58v
6 = 4.6v
7 = 3.8 - 5.2v (fluctuating, approximately)
8 = 9.08v

IC 3 (MN3101)
1 = 9.08v
2 = 4.63v
3 = 0v
4 = 4.67v
5 = 0.33v
6 = 8v
7 = 2.7v
8 = 0.6v

IC 4 (MN3007)
1 = 9.08v
2 = 4.66v
3 = 4.72v
4 = 0.6v
5 = 0v
6 = 4.63v
7 = 4.58v
8 = 4.58v

Q1 (2N5088)
E = 3.68v
B = 4v
C = 9.08v

Q2 (2N5088)
E = 4.19v
B = 4.7v
C = 9.08v

Q3 (2N5088)
E = 3.79v
B = 4.22v
C = 9.08v

Q4 (2N5088)
E = 0v
B = 0.28v
C = 8.49v

Q5 (2N5088)
E = 2.2v - 3.1v (fluctuating, approximately)
B = 2v - 3.6v (fluctuating, approximately)
C = 9.08v

thank you for any input

[Scruffie]

Hmm... okay might be your BBD.

Try an audio probe at the entrance and after the BBD to see if it's passing signal.

Don't forget that the trim works as your v.ref and BBD bias so if you have signal on the input to the BBD, be sure to adjust it as you check the output.

[slim_blues_boy]

ok, I'll try to trace with audio probe,

meanwhile, these are my BBD.

MN3007:




MN3101:




got the MN3207/MN3102 from working unit karaoke mixer machine, so they're suppose to be genuine.
the MN3101 looks suspicious since it looks different from the other.
meanwhile the MN3007 has similar appearance with the MN3207/MN3102, although the font color slightly less visible than the MN3207/MN3102.

[Scruffie]

By appearance, the 3007 looks legit (although that is just by a look) doesn't mean it's not dead though.

The 3101 looks odd but it may just be a different mould, there was a few kinds, or for aesthetic reasons they may have refinished it, anyway you seem to have a working clock although without a scope can't be 100%.

So photos don't mean everything but they seem okay.

[Bret608]

I do have a question--are you building a version of the Pork Barrel that requires a different configuration of jumpers to allow either MN3007 or MN3207 to work?

If I remember correctly from my own build, the pinout on these is not interchangeable, so I got concerned when I saw you had both of those in your picture. I know voltages are most helpful, but I think it would also be really helpful if you posted pictures of both sides of your board. That way, we could help check if you have the right combination of chip and jumpers, if that applies according to what version you're building.

[Scruffie]

I do have a question--are you building a version of the Pork Barrel that requires a different configuration of jumpers to allow either MN3007 or MN3207 to work?

If I remember correctly from my own build, the pinout on these is not interchangeable, so I got concerned when I saw you had both of those in your picture. I know voltages are most helpful, but I think it would also be really helpful if you posted pictures of both sides of your board. That way, we could help check if you have the right combination of chip and jumpers, if that applies according to what version you're building.

He has them right for the 3007 

Pin 5 of the 3007 & Pin 3 of the 3101 are going to gnd as they should.

[Bret608]

Ah! I should have known you'd be able to tell by the voltages.    I always learn something about BBD circuits from you!

[slim_blues_boy]

Bret, I'm using old file from project archive, on the PDF it said Pork Barrel ver2.0. it was for MN3007 only.
meanwhile the latest Pork Barrel could use both MN3007 and MN3207.
I showed the MN3207 just for comparison  .

by the way, the Pork Barrel now working   .
just like Scruffie said, the BBD seems okay, and indeed they all okay.

I don't know what's wrong, I'm about to use audio probe. and before I did that, I tried it one more time, and voila, it's working!

thank you for all of your input guys .

now I can move on to another modulation effects, crazy about modulation lately.

[Bret608]

That's good to hear!    I remember how happy I was when I got my PB working!

[slim_blues_boy]

it always feels great after some quite time for debugging, and finally got it working. plus this is my first take on modulation effect. so yes, really enjoyed the moment  .