Rust Bucket debugging

[Jebus]

Hello!

I just finished my Rust Bucket. I don't get any effected output. Blend works.

Took out my audio probe and started to mess with it. MN3007 outputs effected signal. Junction of R28, R29 and R30 has signal. Nothing can be heard at pin 2, 3 or 6 of IC11 or after that. So, I assume that the problem lays in that area.

I have checked all the values of components around IC11 and they seem to be good (except I have 33n in C17 instead of 27n).

Voltages:
Supply 17,85V

IC11 (CA3080)
1 0
2 0
3 0
4 -14,74
5 -14,74
6 0
7 15,14
8 0,01

IC12 (LM741)
1 -14,72
2 0
3 0
4 -14,73
5 -14,72
6 0
7 15,13
8 0,01

When I compare my voltages to ones in the build document I notice that there is supposed to be small voltages where there are zeros on my measurements. I tried to measure them with the most accurate setting of my DMM (200mV area), but I cant get any good readings. Maybe my cheapo multimeter just can't handle that low voltages.

All ICs have sockets.

Any ideas how to go from here? I'll post some pictures later.

[Govmnt_Lacky]

- Proper orientation of C16?
- Soldering on C16?
- Soldering of sockets on IC11?
- Orientation of ALL ICs on the PCB?

Also... complete list of voltages for ALL ICs and transistors might help 

[Jebus]

- Proper orientation of C16?

Yes, properly oriented.

- Soldering on C16?

Seems to be good, measured. The part feels bit odd though ("wonky"), might need to replace it just to be sure.

- Soldering of sockets on IC11?

Checked, seems to be connected properly.

- Orientation of ALL ICs on the PCB?

Seems to be good.

Also... complete list of voltages for ALL ICs and transistors might help 

I'll start working on this.

[Jebus]

Here's the pictures I promised. I can get better ones tomorrow when its bright outside again.





If you wonder what's going on with the resistors on the non-component side: I had to use some 1W resistors since I failed one order. Also R60 and R61 (18k both) are made with two 33k resistors in parallel (which gives resistance of ~16,5k) and R64 (150R) is made with two 330 ohm resistors (~165 ohm).

[Martan]

Can't help but wonder if something with your parallel  18 k resistor network is sending your signal to ground after pin 6 of ic11

[Jebus]

Can't help but wonder if something with your parallel  18 k resistor network is sending your signal to ground after pin 6 of ic11

I triple checked the values and visually inspected these, but can't spot any obvious error. I reflow the joints later today just to make sure.

[Jebus]

Had a bit more time to debug this. I changed C16 for a new one and tested the pedal -> no effected output. Didn't use audio probe at this point. Then I started to go through the resistor sizes. Found an incorrect one (15k vs 1.5k in R62). Still no effected output, but either that or new C16 changed things bit: now I can hear effected signal from pin2 of IC11 (CA3080), but not from pin6 (or pin3, but I'm not sure if its supposed to be heard there..).

I'll try to get voltages up tonight or tomorrow. I'm starting to suspect IC11 though.

[Jebus]

Phew, finally had enough time to measure all the voltages. I started a new job and suddenly pedal building time decreased to non-existing.

Anyways, here are the voltages:
Supply 17,89


IC1
0
0,01
0,01
-14,74
0
0,01
-0,14
15,14

IC2
0
0
0
-14,74
-14,2
0
15,14
0

IC3
-0,01
0
0
-14,74
0
0
0
15,13

IC4
0
0,01
0,01
-14,74
-0,05
-0,06
-0,15
15,14

IC5
-7,37
-7,41
-7,39
0
0
0
-14,74
-14,74
-14,74
-7,39
-7,39
-14,74
-7,37
0

IC6
0
-7,39
-7,82
-13,83
-14,74
-7,39
-7,68
-7,72

IC7
14,91
0
0
0,06
0
8,38
0
0
0
0
0
0
14,91
14,91

IC8
VARIES
VARIES
0,36
0,34
14,91
8,38
0
0
0,04
0,34
0
0
0
14,91

IC9
0,04
0,04
0,04
-14,74
0
0
-0,43
15,14

IC10
0
0,04
11,98
0
14,82
14,82
0,06
14,91

IC11
0
0
0
-14,74
-14,74
0
15,14
0,01

IC12
-14,73
0
0
-14,74
-14,73
0
15,14
0,01

IC13
1,39
8,48
0
-6,44
-14,74
2,55
1,39
15,14

Q1
-14,2
0
0

Q2
-14,72
-0,02
0

Q3
7,63
0,79
0,33

Q4
8,38
-0,58
0,33

Q5
-14,74
-0,43
0

Q6
-14,44
0
0,48

Q7
-14,74
-14,16
-14,73

Q8
-14,74
-14,12
-14,74


Since my DMM doesn't have auto range feature everything was measured with 20V setting.

I compared them to Brians measurements while I was measuring. Lots of weird voltages on my build (like Q4). Any ideas what I should do next? I think I'm bit lost.. Pin 2 of IC11 is last place where I can hear the effected signal.

[Jebus]

Hey guys!

Spent bit more time trying to figure out whats wrong with this one. Went trough all the resistors and capacitors and found an incorrect one: R32 was 2.7M instead of 270k. Replaced it, but still no effected sound at output.

Next I will swap IC11 and IC2 and see if that makes any difference. Still suspecting IC11 to be faulty. Any other ideas?

[Jebus]

Next I will swap IC11 and IC2 and see if that makes any difference. Still suspecting IC11 to be faulty.

Nope, wasn't it. Swapped those ICs around and no difference. I hear effected signal on the input (pin 2) of IC11 but not in the output (pin 6).

Starting to get really frustrated. I've probably spent five times more time on the debugging than on the building of this pedal. Maybe I should just buy new PCB and start from scratch.. 

[m-Kresol]

on the pic of the solder side. The left resistor soldered in on the back. It's hard to see but make sure it doesn't touch the solder joints on top.

[Jebus]

on the pic of the solder side. The left resistor soldered in on the back. It's hard to see but make sure it doesn't touch the solder joints on top.

Yeah, looks like it in the picture, but sadly that's not case. Went though all the solder joints and visually inspected board, but didn't find anything wrong.

[Jebus]

Hey everyone!

I just wanted to let you know that I'm still fighting with this one. I replaced all the resistors with correct values (no more biggybagging, yay). Sadly that really didn't change anything.

I started messing with audioprobe while strumming guitar and turning all the knobs. I realized that Sense and Decay -pots don't do anything. There is no delay effect if I audiprobe from for example pin 2 of IC11. Could this be because of bad CD4013 or CD4066? I need to try find couple of more of those (usually buy extra ones, I just need to find where they are..).

Any other ideas are welcome also. I'll take new pictures as soon as I have time and its still bright outside..

[Bret608]

Hey, I'm sorry to see this so late, and I imagine you've already checked this. But anyway, in your picture of the solder side of the board, I see what may be a joint with too little solder on the top row of IC6. I haven't built a Rust Bucket myself; this is just what I think my eyes are seeing! 

[wgc]

No offense intended but there's a number of solder joints that look a bit cold. Especially on the pots. Also double check that the body of your resistors isn't too far in the hole and not making proper contact. A little flux and a little more heat should help a lot.