Porkbarrel de-bug

[the3secondrule]

Just finished my Porkbarrel. I'm getting signal on bypass, and when the pedal is engaged im getting clean signal, no chorus.  when I flick the vibe switch, i lose all signal (which makes sense as it kills the clean signal, and thats all I have at the moment),.

can anyone post voltages for me to check mine against?

Also, I bought my 3007/3101 off ebay. the seller had good feedback, but now im pretty worried they are fake.

any Ideas where I should start to debug? is a fake BBD the most likely answer here?

Cheers,

Jeremy

[the3secondrule]

ok - voltages - any help would be greatly appreciated 

(ECB)
q1  4.8    5.1   7.92
q2  5.16  5.65  7.89
q3  4.91  5.2    7.9
q4  0      .689   0
q5  3.1*  3.6    7.74

ic1  5.9    5.9   5.9  0      5.9   5.9   5.9    7.85
ic2  *      3.93  *    0      3.9   3.9   4.01* 7.84
ic3  7.71  7.48  1.0  7.59  6.76 7.03 0.65   7.33
ic4  7.69  7.62  5.09 7.33 0      7.63 7.68   7.7


* indicates the reading was changing...

Cheers

J

[jkokura]

K, so knowing that your dry path seems to be working, chances are you're almost there, and either there's a bad solder joint in there or a faulty/wrong/backwards part in the effected path.

Do you know how to use an audioprobe? That would likely be the best tool to use and solve the problem. If you don't have one, my next suggestion would be to get out the schematic, and begin to trace backwards from the output of the board along the path the effected symbol follows. You should check these things, in no particular order:

Are all the parts correct? (ie, it's easy to put a 100R resistor instead of a 100k resistor in)
Are all the parts the right way? (Backwards transistor, cap, IC, etc.)
Are all the parts installed properly? (Carefully examine your solderjoints, reflow any that look suspicious)
Are all the traces connected? (It's easy to have a broken trace ruin your day! Ignore if this is a manufactured board)

Hope that helps.

Jacob

[the3secondrule]

thnaks Jacob - never used an audio probe, but now seems like a good time to learn 

i'm just wondering  - I didn't have any 1uf electros - so i used poly film caps - would this make a difference - I know usually is fine to sub film caps for electros, but this is one of the more complex pedals I've built.

Also - is there anyway I can check if my 3007/3101 are actually working? still nervous about the ebay seller....

and how do those voltages look?

Cheers

[eniacmike]

two of the 1uf's are coupling caps and should be fine to substitute for poly film. c12 is connected to cp2 clock input 2, and I am not sure how bbd's work but it is connected to ground. alot of times caps connected to power or ground shouldn't be subbed. I don't have a ton of experience with bbd's though.

[jkokura]

I didn't record my voltages for my Pork Barrel build. I wonder if we should start telling Brian to include them in the build documents... What 'should' they be for a working build. Your one tranny that has '0's is strange to me, but i haven't looked at the schem to tell if it is or isn't fishy. Most transistors should not have 0's like that, but it might be a specific case.

Yes, if you have bad IC's you could be experiencing problems like this. I have no sure way to tell you how to solve it, though getting verified IC's could solve the problem. I've always kept it safe, and expensive, and gotten my stuff from Smallbear. Pricey, but peace of mind is mine.

Mike sounds like he's got it right on the caps. You shouldn't sub parts unless you're sure of what you're doing I don't think. Sometimes a small variety in value is just fine, but changing the type of parts doesn't always work. Like with tantalum caps in a Tubescreamer, which will sound very different without them, or Polarized caps in the power section like Mike's suggestion.

Go through things like I suggested, and see what happens. Can't hurt right!

Jacob

[the3secondrule]

If you don't have one, my next suggestion would be to get out the schematic, and begin to trace backwards from the output of the board along the path the effected symbol follows. You should check these things, in no particular order:

Are all the parts correct? (ie, it's easy to put a 100R resistor instead of a 100k resistor in)
Are all the parts the right way? (Backwards transistor, cap, IC, etc.)
Are all the parts installed properly? (Carefully examine your solderjoints, reflow any that look suspicious)
Are all the traces connected? (It's easy to have a broken trace ruin your day! Ignore if this is a manufactured board)

okay - traced the effected siganl back to the BBD on the schem, and as far as i can tell I have everything right. I dug out a 1uf electro and replaced the film cap in c12
I'm using a fabbed board, so the traces should be sweet

It would be good to have some voltages to confirm mine against - otherwise I'm starting to think it is my IC's that are the problem, and I'll have to get a set through smallbear. even if I have to get a new set, it would be good to confirm my voltages, so that I don't fry new chips if there is another fault...

[madbean]

May I ask where you got the BBD set from...I mean, which eBay seller? Voltages are way off. The circuit is under-powered, which is most likely the cultprit.

What type of supply are you using? If it's battery, try using a new one. If it's a power supply, either it's not working properly OR somehow your 9v is turning into 7.8v. IC1 should have 9v on pin8. Also, make sure you have used a 33R on R40, and not 3k3 or 33k.

If using 2n5088, 2n5089 transistors, the pinout is CBE. Q4 should be 0v on E, but not C...which gets it's supply from Vd which is created by R40 (hence the comment above). Anyway, even accounting for the pinouts being in the wrong order there, those voltages are looking off. The emitters should have the lowest voltages, but should not be that high. I wonder if there is also a grounding issue somewhere.

When I get back, I will add in voltages for this project into the documents.

[the3secondrule]

May I ask where you got the BBD set from...I mean, which eBay seller? Voltages are way off. The circuit is under-powered, which is most likely the cultprit.

What type of supply are you using? If it's battery, try using a new one. If it's a power supply, either it's not working properly OR somehow your 9v is turning into 7.8v. IC1 should have 9v on pin8. Also, make sure you have used a 33R on R40, and not 3k3 or 33k.

If using 2n5088, 2n5089 transistors, the pinout is CBE. Q4 should be 0v on E, but not C...which gets it's supply from Vd which is created by R40 (hence the comment above). Anyway, even accounting for the pinouts being in the wrong order there, those voltages are looking off. The emitters should have the lowest voltages, but should not be that high. I wonder if there is also a grounding issue somewhere.

When I get back, I will add in voltages for this project into the documents.

BBD set was from seller "goodbuy711" - I had a feeling it was too good to be true - but they had 100% good feedback. I'll try and get the voltages right before I hunt down another set

I was checking the voltages using a battery - but the pedal is not working with a power supply either- I will check the voltages off a regulated power supply tomorrow though - I'll check r40 again as well

pinout should actually read (i'm using 2n5088)
(EBC)
q1  4.8    5.1   7.92
q2  5.16  5.65  7.89
q3  4.91  5.2    7.9
q4  0      .689   0
q5  3.1*  3.6    7.74

[Micpoc]

I'll be very interested in hearing the outcome of this, as I purchased my set from the goodbuy711 as well (don't want to hijack the thread, as the problem I'm experiencing isn't exactly the same).

[madbean]

I think there's always a chance of fakes, but the MN3007 and MN3101 are still pretty prevelant so I don't necessarily assume that (as opposed to say, the MN3005).

Anyway, as I said: the voltages are the problem. Figure out how 9v is turning into 7.8v and most likely this will solve it.

[the3secondrule]

ok - R40 is definately 33r

new voltage (using regulated power supply)

jrc4558
4.5
4.5
4.5
0
4.5
4.5
4.5
9.1

tl062
*
4.5
*
0
4.5
4.5
*
9.1

mn3101
8.95
8.6
0
8.8
7.96
8.3
0.65
8.5

mn3007
8.9
8.8
3.8
8.5
0
8.6
9
9

EBC
q1   3.59  3.95  9.1
q2   3.85  4.37  9.1
q3   3.68  4.08  9.11
q4   0      0.69  0.04
q5   *      *      8.9

* = changing readings...

[the3secondrule]

Ok - have made myself an audio probe, and gone over the circuit.

I have signal up to the 3007 - guitar on pin 3 - and after the 3007 (pin 7-8) i just get a high pitched whine.

[the3secondrule]

I'll be very interested in hearing the outcome of this, as I purchased my set from the goodbuy711 as well (don't want to hijack the thread, as the problem I'm experiencing isn't exactly the same).

feel free to high-jack the thread  - you might help me figure out what I've done wrong 

[Micpoc]

I'll be very interested in hearing the outcome of this, as I purchased my set from the goodbuy711 as well (don't want to hijack the thread, as the problem I'm experiencing isn't exactly the same).

feel free to high-jack the thread  - you might help me figure out what I've done wrong 

Well, MY problem was that I (was) getting a straight signal when bypassed, no sound whatsoever when engaged, and a muddy (loaded?) signal when engaged with the battery disconnected.  At this point, I've detached the switch and am going to try wiring the jacks straight to the board, to see if I had a switch problem, before delving deeper into the board itself.  Also, the battery I was using measured 7.9V, but I don't know if that would have been sufficient to completely silence the engaged effect.  I'll post more when I've got the jacks wired up, and if I have the same problem, I'll try to get some voltage readings posted.