Tonepad Small Stone Help Needed Please

[pakrat]

Hello all,
I recently built the tonepad version of the small stone (Piedrita) using a board I etched. It didn't work right out of the gate, and I've been debugging for the last few days without success.
I have checked all of my solder points for shorts and cold joints, and all seems ok. Going through it with an audio probe didn't prove useful, since the signal is clean throughout.
I am using a DPDT switch for color, and a 1M rev log pot for depth (C1M).
I have read all posts regarding this and have learned a lot, but not found my answer. I'm hoping someone here can help with this because I'm out of ideas.

1.What does it do, not do, and sound like?
It passes clean signal when bypassed. When engaged there is no phasing, just a slight volume drop with clean signal. The color switch gives more volume drop, and the depth pot does not seem to have any affect.

2.Name of the circuit
Tonepad Small Stone (Piedrita) Rev 6

3.Source of the circuit (URL of schematic or project)
http://www.tonepad.com/project.asp?id=11

4.Any modifications to the circuit? Y or N
I had originally changed R4 to 47k for the volume drop fix, but changed it back to 100k when the effect didn't work.

5.Any parts substitutions? If yes, list them.
Instead of 15k resistors for R3, and R17, I used a 12k and 3k resistor wired in series to make 15k (I didn't have 15k resistors at the time).

6.Positive ground to negative ground conversion?
No

7.Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage?
9.14v using a 300ma 9v adapter.

Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:
Voltage at the circuit board end of the red battery lead
No battery clip is installed.

Voltage at the circuit board end of the black battery lead
0v

Now, using the original schematic as a reference for which part is which (that is, which transistor is Q1, Q2, etc. and which IC is IC1, IC2, C1, and so on) measure and list the voltage on each pin of every transistor and IC. Just keep the black lead on ground, and touch the pointed end of the red probe to each one in turn. Report the voltages as follows:

Q1 2N5088

C 3.31
B 0.71
E 0.49

Q2 2N5087

C 0.73
B 3.31
E 3.85

Q3 2N5088

C 3.82
B 1.80
E 1.30

Q4 2N5088

C 3.85
B 1.30
E 0.77

Q5 2N5088

C 3.82
B 1.80
E 1.31

Q6 2N5088

C 3.85
B 1.31
E 0.78

Q7 2N5088

C 3.82
B 1.78
E 1.28

Q8 2N5088

C 3.85
B 1.28
E 0.76

Q9 2N5088

C 3.82
B 1.80
E 1.30

Q10 2N5088

C 3.85
B 1.30
E 0.75

Q11 2N5087

C 2.13
B 1.51
E 2.14

Q12 2N5087

C 1.57
B 2.13
E 2.14

Q13 2N5088

C 3.82
B 1.18
E 0.68

Q14 2N5088

C 1.51
B 0.68
E 0.10

I realize these voltages are all low compared to other posts I have read. At the 9v input, before the 470 ohm resistor (R2), I get 9.14v After the resistor, it reads 3.84. That didn't seem right, so I took the resistor out and measured it. It was correct at 470 ohms.
So then I replaced R2 with a 100 ohm resistor. That did up my voltages, but still no phasing. R2 has since been put back to stock at 470 ohms. I have also swapped out transistors and IC's with no improvement.


Here are my IC voltages. All IC's are CA3080E.

IC1 CA3080E

1 0.05
2 1.06
3 1.07
4 0.00
5 0.07
6 1.80
7 3.85
8 3.13

IC2 CA3080E

1 0.05
2 1.05
3 1.07
4 0.00
5 0.07
6 1.80
7 3.85
8 3.14

IC3 CA3080E

1 0.05
2 1.05
3 1.07
4 0.00
5 0.07
6 1.80
7 3.85
8 3.14

IC4 CA3080E

1 0.05
2 1.05
3 1.07
4 0.00
5 0.07
6 1.78
8 3.13

IC5 CA3080E

1 0.00
2 2.13
3 1.51
4 0.00
5 0.07
6 1.17
7 3.85
8 2.52

I have checked every resistor using a color code chart, and I believe all of them to be correct. I originally got electros for C6, C7, C10, and CA by mistake, but the layout called for NP caps so I used 0.1uf poly film caps that I had laying around. They are rated at 250v though, not sure if this should affect anything.
I would appreciate any input on this as I have few hairs left to pull out. Sorry for the long post.
Thanks in advance guys!

[PRR]

> I have checked all of my solder points

Thanks for the over-size pictures.

To my eyes, those joints can not be trusted. Many of them do not have clear sign that solder is "stuck" to the wire. Many look like a "crater", as if the wire is repelling solder.



If you worked for me, I'd make you beat _all_ the solder off, tin the leads, tin the pads, be sure there's fresh shiny "wet" solder on lead and pad, _then_ join lead to pad.

While it is perhaps possible all the joints "work" today, to my eye they are likely to quit working unexpectedly. I would not do the hard-thinking of debugging when the joints looked dubious.

Leads generally need more heat than pads. I contact the lead, then shift to contact both led and pad.

Part leads oxidize in storage. If parts are a few months old, and you use activated flux, it should work. This often works for parts a few years old. When in doubt, you should use a Scrubbie or fine emery paper on the leads. (And of course the PCB pads usually need a scrubbie.)

[pakrat]

Thanks a lot for the reply Paul. While I totally agree with you on this, some of those points definitely look worse on the pic. I am now in the process of redoing every joint being sure to get good contact on the leads and pads. I will post a new pic when I'm finished. In the meantime, do you have any insight as to why my voltage drops to 3.84v after R2?

[pakrat]

Ok, I have cleaned up pretty well. There is still no effect, but the color switch now gives me the good ole siren sound in one position, the other position it is just clean sound going through. If I run it without IC5, the whine goes away.

[PRR]

All your goodies are socketed? Being sure you know what goes where, start taking them out. Clip-lead your meter after R2. Power down, remove a chip, power up, read meter. If still 4V or 5V, power-down, remove another chip. Repeat until you suddenly get 8V+. If you run out of chips, start taking transistors out.

[pakrat]

Ok, I just tried that, and it would go up about 1 volt for each chip I removed. Im at 8.57v after all 5 IC's are removed. Thanks for the follow up, I really appreciate it!

[pakrat]

Last night I went through this with a fine toothed comb.... no shorts or bridges anywhere. My signal passes through clean, and after changing RR7 to 39k and R42 to 100k, I no longer have a volume drop when the circuit is on. I have replaced R2 (470 ohm) with a 100 ohm resistor, and I'm getting better voltages on the Ic's. For some reason, I think this all points to the LFO (IC5), because it is definitely not oscillating, and the max voltage on pin 5 is about 0.18v with the depth pot all the way down. The voltage doesn't vary at all on any of the pins of any IC's. I have also swapped around the IC's and tried other CA3080's I have and nothing changes. All transistors have also been swapped around with fresh ones. Signal passes through when the circuit is on, color switch seems to lower volume a bit and maybe lower tone..... no phasing at all.

[PRR]

> the LFO (IC5), because it is definitely not oscillating

I have only a scant idea how that LFO should work.

However pin 5 has to come up to 0.5V-0.6V or nothing will happen. Re-study the 1Meg pot, 27K, 7.5K network.

Do _NOT_ short pin 5 to any other point!! Most pins on most chips are somewhat protected. This pin, anything over 0.5V with no resistance will BLOW the little transistor inside pin 5. Do your poking at the pot where you are less likely to slip and contact other voltages.

[pakrat]

Turning the pot, I get a range of about 0.1v to  0.13v on pin 5 of IC5 (higher than .05v, is it dead now?), reading the pot lugs gives me the same readings on lugs 1 and 2, lug 3 is 0.00v. I have tried a bunch of ca3080's in different sockets to see if any would oscillate in the socket of IC5, and none do. This is only my 4th pedal build, so I'm a newb... IC5 is supposed to sweep voltages of the other 4 IC's correct? Do you think it would be helpful to post my new voltage readings of all transistors and IC's? I still think it's strange that I only get "realistic" voltages with the 100 ohm resistor on the 9v input (R2) instead of 470 ohm. I read in other posts of people doing that mod. Again, thanks for checking in again man, you have been helpful.

[pakrat]

Here are my new voltage readings. This is with a 100 ohm in R2 instead of 470 ohm:

Q1 2N5088

C 6.96
B 2.57
E 3.21

Q2 2N5087

C 5.94
B 6.97
E 7.52

Q3 2N5088

C 7.48
B 5.50
E 5.00

Q4 2N5088

C 7.55
B 4.96
E 4.37

Q5 2N5088

C 7.50
B 5.50
E 5.00

Q6 2N5088

C 7.56
B 4.99
E 4.41

Q7 2N5088

C 7.52
B 5.49
E 4.98

Q8 2N5088

C 7.56
B 4.98
E 4.40

Q9 2N5088

C 7.56
B 5.46
E 4.98

Q10 2N5088

C 7.56
B 4.99
E 4.38

Q11 2N5087

C 1.20
B 0.56
E 1.83

Q12 2N5087

C 1.76
B 1.20
E 1.83

Q13 2N5088

C 1.30
B 0.59
E 1.31

Q14 2N5088

C 0.59
B 1.30
E 0.58


IC'S (ALL CA3080E)

IC1

1 0.26
2 3.82
3 3.80
4 0.00
5 0.34
6 5.51
7 7.54
8 6.82

IC2

1 0.27
2 3.84
3 3.80
4 0.00
5 0.33
6 5.49
7 7.53
8 6.82

IC3

1 0.23
2 3.85
3 3.81
4 0.00
5 0.34
6 5.46
7 7.54
8 6.82

IC4

1 0.27
2 3.81
3 3.78
4 0.00
5 0.33
6 5.43
7 7.53
8 6.81

IC5

1 0.07
2 1.19
3 0.59
4 0.00
5 0.13
6 0.59
7 7.53
8 0.11


Does anyone happen to know what the correct voltages should be?

[PRR]

Voltages in the 1Meg pot, 27K, 7.5K network, pot at both extremes.

Pot at 10:
IC5 end of pot
27K+7.5K end of pot

Pot at 0:
IC5 end of pot
27K+7.5K end of pot

[pakrat]

Pot at 10:
IC5 end of pot 0.01
27K+7.5K end of pot 1.61

Pot at 0:
IC5 end of pot 0.13
27K+7.5K end of pot 0.13

[PRR]

Sure looks like a fried '3080.

[pakrat]

I was actually thinking that myself, so I tested each of the 10 different ca3080's I have one at a time in socket 1 with all other IC's removed. All readings were nearly identical with a difference of .01v here and there. I would like to assume all of 'em are ok because of that, but who knows. I guess I'll order a fresh set of IC's and transistors to rule out damage to them while debugging. If that doesn't work, I'll call this a failed build and start something else I guess. Thanks for your help Paul, I actually did learn a lot from this, even if it was unsuccessful.

[chromesphere]

Hey Pakrat,

Oh yeah!  I remember this one!  Back when dinosaurs roamed the earth, well, approx 2 years ago, i decided to build 2 of these.  One worked straight up, the other played up so much, i almost threw myself off a cliff.

Anyway, Oskar, a member of the forum went through alot of the voltages etc with me, and explained some stuff about the circuit.  I found it invaluable to put me in the right direction and i finally got it working.  Hope it helps and persist, you'll get there!

Paul

http://www.diystompboxes.com/smfforum/index.php?topic=73734.msg598549#msg598549

[pakrat]

Wow, thank you very much chromesphere! I thought I had read EVERY post about this thing. I have read through a few times already..... after a few more reads, I might get it hahah! I was feeling like I needed to start over on this one, I hope not! Did you happen to leave that 470 ohm resistor in R2? For some reason I have a big voltage drop after it, so I changed it to 100 ohm. I think I will change it back to 470 to troubleshoot. Sheesh......

[chromesphere]

Hey pakrat, Np, i hope it helps.

Not sure about the 470 res.  I subbed the 'volumn drop' resistor, to increase the output slightly, but everything else is stock.  If it helps, give me a few points you want me to test and ill check my voltages when i get home tonight.  I sympathise.  The small stone is one of the few builds that nearly broke me.

I dont know how much experience you have with this stuff, so i thought i would throw a few 'basic' troubleshooting things i do when i check over my stuff.  Oh actually, its easier if i just point you to my video!  lol.  scratching the tracks, resoldering dodgy looking solder joints (or just resolder them all to be sure) and checking the component values are probably the best place to start. I had a combination of issues, but it was a dodgy solder joint for me, and you couldnt even tell by looking at it.

http://www.youtube.com/watch?v=JnD4-_Fhd90&list=UUGhzS1GbX-yxyBrUJtnUMoA&index=11&feature=plcp

Good luck!

Paul

[pakrat]

Paul, I'm sorry, but I AM going to take you up on your offer to compare some voltages hah! I really appreciate you taking the time to help me on this one. I'm not a total noob but reading some of the threads around here definitely makes me feel like one... there are some seriously smart people here! I have built a few pedals, the one that gave me trouble about a year ago was Dr Boogey. I requested help in here and got it working. I have already double checked values, resoldered every point as PRR suggested, and cut between all tracks. I also did hold the pcb to the light as your video suggests and it looks good (great video by the way). I even put a photo of my board up against the layout in photoshop with some opacity removed to see both and it looks good. I must have something shorted though because it would work if it was right! I feel like I've done everything I can do and wanted to blame it on bad components, but I'm only human and not overly experienced building these (this is my 5th pedal). I appreciate your help!

[chromesphere]

Sounds like you have checked alot of the boxes that i usually check when troubleshooting...hmmm.  I also had a dead ca3080.  This was a seperate problem, but after about 3 months, i found that the effect sounded "stuck" and wasnt oscillating.  I put in a new Ca3080 and it fixed it.  I think i read you've already tried swapping the ic's though.

It's cool, send me the points you want to check specifically.  "ic1 pin 5"  "r5" etc.  Give me a handful of the ones you are suspect about, I will check them tonite.  5 mins of my time might save 5 hours of yours. ;-)

Paul

[pakrat]

Thanks a lot man, really. I have no "correct" voltages to compare to mine, so it has been difficult to pinpoint any problems. I get no wet signal whatsoever, my signal passes through 99% as it went in, except for a bit of a level drop. I took all IC's out, and one at a time put them in socket 1 and recorded voltages. They were all the same. Can I assume all IC's are either good or bad from this? Can we start with the pot? On the layout, are we looking at the bottom of the pot?
Here are my voltages for the pot, left to right looking at the bottom:
Fully clockwise
1 0.14
2 0.14
3 0.14 (from R22, R23)

Fully counterclockwise
1 1.64
2 0.01
3 0.01 (from R22, R23)

These are not looking good