PCSC - I knew this would be a tough one...

[AntKnee]

Having trouble right off the bat with my Pork Chop. I have the board populated, and I have input, output, +/- wires attached to test. When I only have the input/output connected, it passes clean signal, but as soon as I connect the ground, it goes silent. When I connect the 9v, nothing seems to happen. When I put my probe on the input with the 9v and ground connected, I get a dreadful deep buzz. It sounds almost synth like, but not in a good way. I've been inspecting the board for any bridges and have done some reflowing and scraping to make sure there aren't any, but this has not helped so far.

I also am not sure what the J1 and J2 holes are for on the pcb. Just need some advice on what to check next. Thanks!

[TGP39]

Hey Anthony.....couple questions.
1. Is this attached to your testing rig? If so, could you post a pic of the entire setup?
2. Did you etch this board? It looks pretty good.
3. The power (red wire) and ground look soldered together to me on the pcb? Is it?

We will get this one working too. 

Steve.

[midwayfair]

>When I connect the 9v, nothing seems to happen.

Nothing? Are you sure? If "nothing" happens -- at all -- then it means that your board is not connecting to either ground or power, because no current would flow. Clearly that's not the case.

What are your voltages on the op amps and transistors?

http://www.madbeanpedals.com/forum/index.php?topic=902.0

[AntKnee]

Steve! Long time no chat!
This board is the work of the ever abiding Dude, Haberdasher.
And I made a laughable noob mistake of switching my input and output wires. Ugh.

So, I do have it passing signal and sort of working, but not properly.
The Clean knob is behaving more like the Volume, the tone and overdrive knobs seem to have no effect.
I am wondering what those J1 and J2 holes are for, maybe that has something to do with it.

[AntKnee]

IC1:
1 4.35
2 4.35
3 3.86
4 0.01
5 0.97
6 1.41
7 1.42
8 8.67

IC2:
1 4.30
2 4.34
3 4.27
4 0.01
5 4.27
6 4.34
7 4.36
8 8.67

q1:
D 8.67
G 4.14
S 6.36

[AntKnee]

Q2: E 0.62 B 1.15 C 2.18
Q3: E 4.55 B 2.18 C 0
Q4: E 3.93 B 4.55 C 8.67
Q5: E 0.62 B 1.15 C 2.16
Q6: E 1.57 B 2.18 C 4.56
Q7: E 3.95 B 4.56 C 8.67

Noticed on Q1 thru Q7, I get the same reading touching the top of the transformer as I do on the collector. Is that normal?

[Bret608]

Hey man,

I do not know a ton about ICs, but from the schematic, it looks like pin 4 of each IC is connected to ground. If there's even a touch of voltage there it still makes me think it's a bridge somewhere. I also thought it looks like your +9v and ground pads are soldered together. What you could do is to take you multimeter and with the board not connected to power, use the continuity setting to see if power and ground are connected.

The J1 and J2 pads are just ground pads for the in/out jacks, and would only be used if you went with side-mounted rather than top-mounted jacks.

Let us know how it works out! 

Bret

[AntKnee]

Hey man,

I do not know a ton about ICs, but from the schematic, it looks like pin 4 of each IC is connected to ground. If there's even a touch of voltage there it still makes me think it's a bridge somewhere. I also thought it looks like your +9v and ground pads are soldered together. What you could do is to take you multimeter and with the board not connected to power, use the continuity setting to see if power and ground are connected.

The J1 and J2 pads are just ground pads for the in/out jacks, and would only be used if you went with side-mounted rather than top-mounted jacks.

Let us know how it works out! 

Bret

The picture does appear that way, but I have reflowed them, and verified no continuity from power to ground with my tester.

[the3secondrule]

Q3s voltages don't look right to me.

[AntKnee]

Q3s voltages don't look right to me.

recheck Q3:
E 1.57
B 2.19
C 4.55

Not sure what happened the first time.

[selfdestroyer]

So, I do have it passing signal and sort of working, but not properly.
The Clean knob is behaving more like the Volume, the tone and overdrive knobs seem to have no effect.
I am wondering what those J1 and J2 holes are for, maybe that has something to do with it.

This is the problem I am having with mine also. I swore it all worked before I boxed it but playing with it some more I noticed that the clean controls were not working properly. I will take the voltages of mine tonight and post them to compare to. The OD sounds great but I would love to get the clean blend working properly.

Cody

[AntKnee]

This is the problem I am having with mine also. I swore it all worked before I boxed it but playing with it some more I noticed that the clean controls were not working properly. I will take the voltages of mine tonight and post them to compare to. The OD sounds great but I would love to get the clean blend working properly.

Cody

Yeah, my clean knob is acting as a master. The Volume knob will turn the level down only if the clean knob is up. Tone knob has no effect.  It sounds like the overdrive is all the way up, but the overdrive knob has no effect on it.

[midwayfair]

Hm.

Pull R33 and R34 one at a time and make sure that each side is actually working when the signals aren't being mixed.

Audio probe the base of each transistor in the dry path and see if you lose signal anywhere.

The dry path in this pedal is weird. Why didn't it just use an op amp?

[AntKnee]

Hm.

Pull R33 and R34 one at a time and make sure that each side is actually working when the signals aren't being mixed.

Audio probe the base of each transistor in the dry path and see if you lose signal anywhere.

The dry path in this pedal is weird. Why didn't it just use an op amp?

Thanks Jon. Much respect for your brainitude!

I'm hoping I read the schematic right (still new at this) and correctly deduced that you mean Q5, Q6, and Q7.

With R33 pulled, I get an unchanged tone at the output jack. The base of Q5 gives me an awful wavy buzz, Q6 has clean guitar tone, Q7 has overdriven tone.
With R34 pulled, I get no sound at the output jack and clean tone at all of the bases of Q5, Q6, Q7.

[midwayfair]

Hm.

Pull R33 and R34 one at a time and make sure that each side is actually working when the signals aren't being mixed.

Audio probe the base of each transistor in the dry path and see if you lose signal anywhere.

The dry path in this pedal is weird. Why didn't it just use an op amp?

Thanks Jon. Much respect for your brainitude!

I'm hoping I read the schematic right (still new at this) and correctly deduced that you mean Q5, Q6, and Q7.

With R33 pulled, I get an unchanged tone at the output jack. The base of Q5 gives me an awful wavy buzz, Q6 has clean guitar tone, Q7 has overdriven tone.
With R34 pulled, I get no sound at the output jack and clean tone at all of the bases of Q5, Q6, Q7.

Pulling R33 removes the distortion path -- i.e. nothing from the overdrive section reaches the mixing stage.

Pulling R34 removes the clean side from the equation.

Since you're getting clean signal at the output jack, it looks like your clean side is working. It's your distortion side that's conking out. Reconnect everything as before, and start following the distortion path. You'll want to probe pins 3, 1, 5, and 7 (and 6), as well as lug 3 of the dry mix pot, to see where you're losing signal.

Before you go any further, though, I'm going to suggest a complete reflow on all your solder joints, and you may want to remove and then socket Q1 -- there's a small possibility that the transistor was damaged by static, and there is no protection diode in this design for the MOSFET.