Any knowledgable BBD-based effects guys out there? I need help bad.

[guitylerham]

So I've been trying to build this Leslie simulator called the Baja CX-3 (circuit from the Korg keyboard!). I etched a board, ordered all the parts... obviously it didn't work the first time. I spent HOURS and DAYS trying to read and teach myself how to troubleshoot it. Well after fixing some errors, I made a tiny bit of headway. Then I accidentally reversed power!!! I had no polarity diodes in at the time so I decided (reluctantly) to etch a new board, salvage only the resistors and non polarized film caps. I replaced all Elec caps, IC's and diodes. After feeling pretty confident that I'd fix the problem with a new board, I find that it still doesn't work. MY GOD.

I've gotten some pointers from you all along the way but I need to directly ask for help now! Anyone up for the challenge? This circuit is going into my multi-effect board and I will not give up until I build it. It's a personal constitution it seems.
http://i.imgur.com/zVZbU.jpg

This circuit takes the input, splits it into hi and lo frequencies, then sends each to it's own circuit with a BBD and stuff, then recombines them at the end. The only modifications from the schematic I have done is to use 2N5089's for all the transistors, and MN3007's instead of the original MN3004. I have doubled the clock speed by halving the the clock driver capacitors (making C8 and C22 750pf instead of the original 1N5's). The MN3007 pinouts are identical to 1/2 of the MN3004 that is used. This is a verified circuit even with this modification so I am confident doing so.

IC1 is the hi-freq MN3004 and IC4 is the low-freq MN3004. When probing, I find that signal makes its way to each BBD just fine, however, there is no constant sound from the outputs of IC1, and the outputs of IC4 sound distorted and garbly (adjusting the voltage bias doesn't solve the problem). I'm thinking that there is an issue with the clock driver(s). I've swapped drivers but the problem remains. On IC1, there is a random noise on the outputs though. It is a terrible sounding screeching/static-y/laser gun noise that continues... or goes silent. Pretty intermittent.                  

Also, there is no audio past R95 (after the long straight line in the middle of the schematic). Should there be?

Here are the voltages as I recorded them minutes ago: Power is at +11.96vdc (schem calls for 12vdc)
Q1
E 2.83
C 10.97
B 3.35
Q2
E 2.18
C 6.12
B 2.72
Q3
E 7.77
C 10.97
B 8.29
Q4
E 7.03
C 10.97
B 7.56
Q5
E 0
C 0
B 0.5
Q6
E 0
C 0
B 0.5
Q7
E 0
C 2.74
B 0.3
Q8
E 4.4
C 10.95
B 4.84
Q11
E 0
C 1.87
B 0.31
Q12 (activates "Slow/Fast" setting when fed a small voltage via a switch)
instance A     instance B
E 0              0
C 0.46          0
B 0              0.63

IC1 hi-freq MN3007
1) 11.76
2) random oscillations anywhere from 11+ down to 0
3) 6
4) 1.07
5) 0
6) 11.80
7) 8.35
8.) 8.35

IC2 HEF4046 (hi-freq)
1) 0 nc
2) random oscillations
3) random oscillations
4) same as pin 3
5) 0
6) random
7) random
8.) 0
9) 4.57
10 5.19 nc
11) 10.81
12) 0
13) 11.81 nc
14) 7.49
15) 11.8 nc
16) 10.8

IC3 4558
1) 5.46
2) 5.48
3) 5.48
4) 0
5) 1.59
6) 6.18
7) 6.18
8.) 10.98

IC4 Lo-freq MN3007
1) 11.22
2) 5.56
3) 6
4) 1.01
5) 0
6) 5.59
7) 6.11
8.) 6.11

IC5 Lo-freq HEF4046
1) 0 nc
2) 5.59
3) 5.56
4) 5.56
5) 0
6) 1.44
7) 1.43
8.) 0
9) 5.91
10) 4.59 nc
11) 4.17
12) 8.5
13) 0 nc
14) 11.22
15) 7.39 nc
16) 11.22

IC6 LM324
1) 5.54
2) 5.77
3) 5.8
4) 11.93
5) 5.77
6) 7.75
7) 7.49
8.) 5.76
9) 5.55
10) 5.41
11) 0
12) 3.74
13) 3.84
14) 5.77

So there are all the voltages. I'm thinking the signals are hitting the rails in some of the IC's but I'm just speculating as a novice. Maybe that's why IC4's outputs are distorted, for example. Obviously there are some major things wrong here. Some of the transistors read ok, others not so much. I just don't know what I should be looking for.

My solders look shiny. What are the odds that there isn't continuity through one or more of my solder pads (cold solder?) What can you guys surmise from all of this?

[Thomeeque]

 Hi, just quick reply, more maybe later..

Also, there is no audio past R95 (after the long straight line in the middle of the schematic). Should there be?

No, inverting input of IC-3 opamp acts here as an ground for AC signal (currents from all sources are summed here) - you should get clear signal at R.E OUT, do you?

IC1 hi-freq MN3007
2) random oscillations anywhere from 11+ down to 0
6) 11.80
IC2 HEF4046 (hi-freq)
2) random oscillations
3) random oscillations
4) same as pin 3

IC-2 clock obviously does not work, you should get around half of VCC DC voltage at all these pins - hint: DC readings at IC-1 and IC-2 should approximately match DC readings at IC-4 and IC-5.

(IC-5 = Lo-freq HEF4046, you have two IC6 in post above)

the outputs of IC4 sound distorted and garbly (adjusting the voltage bias doesn't solve the problem). I'm thinking that there is an issue with the clock driver(s).

Maybe you should use original clock capacitor values first and try to speed it up later, when it will be working otherwise. Doubling clock frequency may not be that simple as it looks.

T.

[R.G.]

I etched a board, ordered all the parts... obviously it didn't work the first time. I spent HOURS and DAYS trying to read and teach myself how to troubleshoot it. Well after fixing some errors, I made a tiny bit of headway. ...I will not give up until I build it. It's a personal constitution it seems.

Good for you. You're learning stuff at a furious rate. Learning is *work* when something just has to work. Your being willing to do the work means you'll get there if you don't give up.

This circuit takes the input, splits it into hi and lo frequencies, then sends each to it's own circuit with a BBD and stuff, then recombines them at the end. The only modifications from the schematic I have done is to use 2N5089's for all the transistors, and MN3007's instead of the original MN3004. I have doubled the clock speed by halving the the clock driver capacitors (making C8 and C22 750pf instead of the original 1N5's). The MN3007 pinouts are identical to 1/2 of the MN3004 that is used. This is a verified circuit even with this modification so I am confident doing so.

Good de-composition of the circuit. It is a handy trick to debug in the same way: pick a section of circuit, force all the inputs to be within the normal ranges, then see if a normal output comes out. If not, something is wrong inside that section. It's important to understand that "inputs" in this context means "everything that goes into the section", which includes especially power supplies, clock signals, bias voltages, control settings, etc. This procedure finds all faults that make it not work completely. It leaves the issue of bugs that cause malfunctions only at certain settings of control and signal, but those bugs are in a whole different class, and are not what you're seeing.

Bottom line: divide and conquer.

There is a definitive test for BBDs that tells you if they're good. It amounts to that "provide all good inputs, then look for a good output". You check for (1) valid power supply and bias voltages --> on the chip pins, not the solder joints <-- (2) clean, valid digital clock signals on the clock pins, (3) a proper-sized audio signal at the input pin, and (4) an audio output. If you you have all the first three but not the last one, the chip is dead. One problem is that you need a dual-trace oscilloscope to tell that the clock signals are properly shaped and out-of-phase with each other.

If you find that you don't have any one (or two, or three...) of the input conditions, then you have to back up and get that section fixed to test the BBD.For instance, a bad clock signal **can't** make the BBD operate right. So you'd have to go debug the clock generator to make it work properly. No audio input? Have to get that working before you can tell about the BBD. But in each case, you're looking for "is this signal the BBD needs being provided to it correctly?"                 

Also, there is no audio past R95 (after the long straight line in the middle of the schematic). Should there be?

As noted, no. But there should be audio at the output of that opamp section, even if only the dry signal.

Looking through the schemo, I notice:
Q5 and Q6 are noted "Green x2 selected". You may run into problems with those devices under operation because they have to be hand selected. But that won't keep it from working at all.

Q7
E 0
C 2.74
B 0.3

Q7 and the associated parts of IC6 form a low frequency triangle wave oscillator. This is probably the "rotation frequency". The voltages are approximately correct. Look for a slow rise/fall on pin 8 of IC6.

Q11
E 0
C 1.87
B 0.31

Ditto on the above for this section. It's the other "rotor" frequency.

Q12 (activates "Slow/Fast" setting when fed a small voltage via a switch)
instance A     instance B
E 0              0
C 0.46          0
B 0              0.63

Probably OK. Can't tell until other things get confirmed.

IC1 hi-freq MN3007
1) 11.76
2) random oscillations anywhere from 11+ down to 0
3) 6
4) 1.07
5) 0
6) 11.80
7) 8.35
8.) 8.35

You're working blind here. First, do you *know* that the pin swaps for the 3007 and 3004 are correct? Second, you should see the same oddities on clock pin 2 as clock pin 1. If not, one of the chip "inputs" is not correct. It may be that you're getting a clock signal from the 4046 on pin 2 but not on pin 6. Measure those clock signals back at the pins of the 4046. The 4046 is supposed to be generating them, and they are supposed to be connected to the 3004 through some copper wire and solder. If you get different readings at the two ends of a string of metal, chances are something is wrong in the metal path. This is the place where you really need an oscilloscope, but identically crazy meter readings makes a substitute, if a clumsy one.

IC2 HEF4046 (hi-freq)
1) 0 nc
2) random oscillations
3) random oscillations
4) same as pin 3
5) 0
6) random
7) random
8.) 0
9) 4.57
10 5.19 nc
11) 10.81
12) 0
13) 11.81 nc
14) 7.49
15) 11.8 nc
16) 10.8

There is a bug here, and a bad one. Pin 14 is supposed to be tied to pin 16 to allow the internal XOR gate to make an inverter. Pin 14 is at a different voltage than pin 16, so it *can't* be operating right. Remeasure on the pins of the IC itself, then find out why pin 14 and 16 are different. This could keep one of the clock phases from happening. Or it could be making random contact, giving the intermittent squarks.

IC4 Lo-freq MN3007
1) 11.22
2) 5.56
3) 6
4) 1.01
5) 0
6) 5.59
7) 6.11
8.) 6.11

These should be much the same as the other one. Why isn't the power supply pin the same?

IC6 Lo-freq HEF4046
1) 0 nc
2) 5.59
3) 5.56
4) 5.56
5) 0
6) 1.44
7) 1.43
8.) 0
9) 5.91
10) 4.59 nc
11) 4.17
12) 8.5
13) 0 nc
14) 11.22
15) 7.39 nc
16) 11.22

Note pin 14 and 16 the same. This one has a better chance to be working. Use this one for a model of what the other one should look like to your meter.

My solders look shiny. What are the odds that there isn't continuity through one or more of my solder pads (cold solder?)

If you're using lead-bearing solder, you're probably OK. If you're trying to use lead-free, then it's perfectly possible for it to make a "tent" of solder over a lead and not make contact. I had the misfortune of finding this out on a production run of PCBs. I remember that one very clearly.   

[guitylerham]

You can say furious for sure, RG! Man, I must have gotten my pins mixed up when measuring. Here are the updated readings taken from the pins of the IC's:

Q1
E 2.83
C 10.97
B 3.35
Q2
E 2.18
C 6.12
B 2.72
Q3
E 7.77
C 10.97
B 8.29
Q4
E 7.03
C 10.97
B 7.56
Q5
E 0
C 0
B 0.5
Q6
E 0
C 0
B 0.5
Q7
E 0
C 2.74
B 0.3
Q8
E 4.4
C 10.95
B 4.84
Q11
E 0
C 1.87
B 0.31
Q12 (activates "Slow/Fast" setting when fed a small voltage via a switch)
instance A     instance B
E 0              0
C 0.46          0
B 0              0.63

IC1 hi-freq MN3007
1) 11.76
2) random oscillations anywhere from 4 to 11 but most often around 6
3) 6
4) 1.07
5) 0
6) fluctuations around 6
7)  fluctuates around 6                            
8.) fluctuates around 6

IC2 HEF4046 (hi-freq)
1) 0 nc
2) random oscillations
3) random oscillations
4) random oscillations
5) 0
6) random but centered around 1.5
7) random but centered around 1.5
8.) 0
9) 5.9
10 4.55 nc
11) 4.18
12) 9.7 fluctuates
13) 0 nc
14) 11.72
15) 0.09 nc
16) 11.72

IC3 4558
1) 5.46
2) 5.48
3) 5.48
4) 0
5) 6.07
6) 6.2
7) 6.2
8.) 11

IC4 Lo-freq MN3007
1) 11.22
2) 5.56
3) 6
4) 1.01
5) 0
6) 5.59
7) 6.11
8.) 6.11

IC5 Lo-freq HEF4046
1) 0 nc
2) 5.59
3) 5.56
4) 5.56
5) 0
6) 1.44
7) 1.43
8.) 0
9) 5.91
10) 4.59 nc
11) 4.17
12) 8.5
13) 0 nc
14) 11.22
15) 0.08 nc
16) 11.22

IC6 LM324
1) 5.54
2) 5.77
3) 5.8
4) 11.93
5) 5.77
6) 5.75
7) 5.47
8.) 5.76
9) 5.55
10) 5.41
11) 0
12) 3.74
13) 3.84
14) 5.77

So yeah, IC4 and IC5 are more of the "model students" to compare to it appears.

Good de-composition of the circuit. It is a handy trick to debug in the same way: pick a section of circuit, force all the inputs to be within the normal ranges, then see if a normal output comes out. If not, something is wrong inside that section. It's important to understand that "inputs" in this context means "everything that goes into the section", which includes especially power supplies, clock signals, bias voltages, control settings, etc. This procedure finds all faults that make it not work completely. It leaves the issue of bugs that cause malfunctions only at certain settings of control and signal, but those bugs are in a whole different class, and are not what you're seeing.

I see how this is an important tool to use. I still need to become familiar enough to be able to "force" inputs to be what they ought to be. I'll spend some time trying to demystify each individual circuit.

Q4 and Q5 don't seem to be doing much at all based upon the readings. From the schematic though, it doesn't seem like those two should be getting any positive voltage to the collector so who knows!

You're working blind here. First, do you *know* that the pin swaps for the 3007 and 3004 are correct? Second, you should see the same oddities on clock pin 2 as clock pin 1. If not, one of the chip "inputs" is not correct. It may be that you're getting a clock signal from the 4046 on pin 2 but not on pin 6. Measure those clock signals back at the pins of the 4046. The 4046 is supposed to be generating them, and they are supposed to be connected to the 3004 through some copper wire and solder. If you get different readings at the two ends of a string of metal, chances are something is wrong in the metal path. This is the place where you really need an oscilloscope, but identically crazy meter readings makes a substitute, if a clumsy one.... There is a bug here, and a bad one. Pin 14 is supposed to be tied to pin 16 to allow the internal XOR gate to make an inverter. Pin 14 is at a different voltage than pin 16, so it *can't* be operating right. Remeasure on the pins of the IC itself, then find out why pin 14 and 16 are different. This could keep one of the clock phases from happening. Or it could be making random contact, giving the intermittent squarks.

Yeah, duh, I don't know why I wrote that down wrong. The new readings show the same for all pins that are physically connected.

Quote
IC4 Lo-freq MN3007
1) 11.22
2) 5.56
3) 6
4) 1.01
5) 0
6) 5.59
7) 6.11
8.) 6.11
These should be much the same as the other one. Why isn't the power supply pin the same?

True, 11.2 volts is lower than the 11.72 of IC1. A low power supply could explain the distorted outputs of IC4. I'll take a look at the path from the dc power supply to this pin 1 of IC4.

If you're using lead-bearing solder, you're probably OK. If you're trying to use lead-free, then it's perfectly possible for it to make a "tent" of solder over a lead and not make contact. I had the misfortune of finding this out on a production run of PCBs. I remember that one very clearly.   icon_eek

Oh gosh, after etching the board, I went over every trace with my solder to lay down a tinning. I do use this radio shack silver bearing rosin core solder... I hope I didn't just make this a whole lot worse. I've made ten other circuits just this way for my pedalboard and all work just fine.

Quote from: guitylerham on Today at 12:05:08 AM
IC1 hi-freq MN3007
2) random oscillations anywhere from 11+ down to 0
6) 11.80
IC2 HEF4046 (hi-freq)
2) random oscillations
3) random oscillations
4) same as pin 3

IC-2 clock obviously does not work, you should get around half of VCC DC voltage at all these pins - hint: DC readings at IC-1 and IC-2 should approximately match DC readings at IC-4 and IC-5.

(IC-5 = Lo-freq HEF4046, you have two IC6 in post above)

Thomeeque, thanks for pointing that out. I might try and remove the IC's and measure the sockets and see if they're getting the correct voltage in the first place.

Also, there is no audio past R95 (after the long straight line in the middle of the schematic). Should there be?

No, inverting input of IC-3 opamp acts here as an ground for AC signal (currents from all sources are summed here) - you should get clear signal at R.E OUT, do you?

The output I hear at RE is a mix between the distorted outputs of IC4 and the scary laser squarking of IC1 outputs, of course amplified after the 4558.

Man oh man. Sometimes I wonder why I do this to myself! I'm sure I'm not alone though. Thanks for chiming in guys with your help. It means so much to me!

[guitylerham]

IC4 Lo-freq MN3007
1) 11.22
2) 5.56
3) 6
4) 1.01
5) 0
6) 5.59
7) 6.11
8.) 6.11
These should be much the same as the other one. Why isn't the power supply pin the same?

So looking at the schematic, I see IC4 and IC5 get their power from a 12v supply labled as a boxed 3. At the power supply section of the schematic, I see that the part labeled as a boxed 3 is 12v fed through a 220 ohm resistor, which yields 11.22 volts apparently.  IC1 and IC2 get their power from a supply labeled as a boxed 2. This is the 12v supply fed through a 100 ohm resistor, which apparently yields 11. 72. So I guess this makes sense to me. Is this correct logic? Also, should my 7812 be giving me exactly or a bit more than 12v+? Right now I'm only getting 11.95.

[PRR]

> should my 7812 be giving me exactly or a bit more than 12v+? Right now I'm only getting 11.95.

Read the datasheet against the fine print on your part. They are never 12.00000V. Tolerance may be 2% or 5% in various grades.

However 11.95 (0.4% error) is too spot-on to be your problem.

[guitylerham]

> should my 7812 be giving me exactly or a bit more than 12v+? Right now I'm only getting 11.95.

Read the datasheet against the fine print on your part. They are never 12.00000V. Tolerance may be 2% or 5% in various grades.

However 11.95 (0.4% error) is too spot-on to be your problem.

Thanks, dude. One less thing to worry about.

[guitylerham]

So I rechecked the voltages and now IC1 and IC2 nearly mirror the "proper" working IC4 and IC5! Something must be fishy in the soldering. However, even with the more correct readings, the outputs of the MN3007s are still distorted and warbly sounding. The inputs to the MN3007s are clean and good though so it still must be something in the clock drivers. Would a miscalibration in the clock driver cause distortion in the MN3007s?

[R.G.]

Something must be fishy in the soldering.

This is always the first thing to suspect in a new build. In fact, that statement, all by itself, may be the best first rule of debugging. 

However, even with the more correct readings, the outputs of the MN3007s are still distorted and warbly sounding. The inputs to the MN3007s are clean and good though so it still must be something in the clock drivers. Would a miscalibration in the clock driver cause distortion in the MN3007s?

With those still-unknown soldering problems cleared up, there's another problem to clean up.

We can now go to something I suspected but didn't mention as there were other issues to get first. This thing involves running two LFOs into the 4046's to get a varying ('rotating') clock to the BBDs.  The audio illusion the BBDs make is dependent on just the right clock speeds and the right amount of LFO speed and size. If the LFO signal wobbles the BBD clocks too much or too fast, the illusion is gone and ugly audio results. I don't know that this is what is happening, and can't until I see scope traces or hear you say "ahah! that fixed it", but it's my next guess.

Since you can't scope it (you haven't said, but I'm guessing you don't have an o'scope), the next best thing to do is to force the LFO inputs to be non-varying. This lets you test out whether the 4046's can provide the right clocks indirectly.

Try this: Pull up one end of R36 and R74. These are the resistors that feed LFO to the 4046s. Then temporarily connect a 10K pot from +12 to ground and connect the wiper to the line into 4046 pin 9 on each of them. Set the pot to middle and fire it up. The pot lets you manually adjust the delay time. Now you can hear whether the BBDs provide a clean signal with no LFO warble at some setting of the pot. If this sounds good, at least one more problem is the LFO generators running too fast or too ugly in some way. If it does not, you have (at least) a problem with the 4046s and BBDs. It's another layer of divide and conquer.

If there is no pot setting with good sound through the BBDs, then you have a problem with either the 4046s or the BBDs, and you really do have to either try to solve it by random easter-egging components, or using a scope to see if the clocks are clean.

[guitylerham]

Ok, I will try that test in a couple of hours. Thank you for that cool trick.

So I spotted three errors! Diodes D3, D8, and D9 were in backwards as the layout I'm using was confusing. Resolving this finally gave me some better warble effect that slowed down and sped up as I activated the slow/fast switch. So that is some progress but there is still a very intermittent screeching going on from the BBDs.

That is all for now. Stay tuned!

p.s. yeah, I do not own a oscilloscope.

[guitylerham]

Try this: Pull up one end of R36 and R74. These are the resistors that feed LFO to the 4046s. Then temporarily connect a 10K pot from +12 to ground and connect the wiper to the line into 4046 pin 9 on each of them. Set the pot to middle and fire it up. The pot lets you manually adjust the delay time. Now you can hear whether the BBDs provide a clean signal with no LFO warble at some setting of the pot. If this sounds good, at least one more problem is the LFO generators running too fast or too ugly in some way. If it does not, you have (at least) a problem with the 4046s and BBDs. It's another layer of divide and conquer.

So I pulled up one end of R36 (the end that contacts pin 9 of 4046), put a trimpot wiper in that pad and positive and ground on the other two ends of the trimpot. Is that correct (see picture)?


Immediately, the output of that MN3007 cleaned up, however not much happened when I adjusted the trimpot. Thinking that I had this wired wrong, I then completely removed R36 and just put one lead of the trimpot in a pad and the wiper in the other pad so that now I had a basic variable resistor in place of R36 that went from 0 ohms to 10k. On one extreme, the distortion cleaned up but not as good as when I had wired it the first way, the other extreme was a gargled mess. I don't think I did any of this right!

[R.G.]

So I pulled up one end of R36 (the end that contacts pin 9 of 4046), put a trimpot wiper in that pad and positive and ground on the other two ends of the trimpot. Is that correct (see picture)?
... I don't think I did any of this right!

Actually, you did. The first way was what I meant. Put it back that way. Once you're there, use your voltmeter and see if turning the pot can make the wiper voltage vary a goodly amount around the middle of the power supply (i.e. 6V). If it can, set it to 6V. If there is, check for reasonably clean audio at the emitter of Q4.

If you have clean audio at Q4, lift one end of R97. This last stops any audio from the lowermost (in the picture) 3004 from getting through, good or not. Now you're only listening to the dry audio through R95 and one set of delayed audio through R94. Oh, and the amplitude modulation from the top LFO, but that's been killed off by lifting R36. With this set up, you should be able to hear some vibrato or flanging, even if slight, as you turn the pot. Well, you will if the 4046 is running correctly and it was the LFO that was hosed.

If you hear no audio at the emitter of Q4, then the 3004 is not passing audio, and either the 4046 or the 3004 is hosed.
If you hear clean audio at the emitter of Q4 and turning the patched-in pot does nothing to the combined sound at the output, then the 4046 is (probably...) making good clocks but is not being modulated by the pot movement, or is running at so high a frequency that there is no delay perceptible.
If both are working OK, you'll hear some kind of flanging/vibrato sound.

[guitylerham]

Ok, so do I run a wire from pin 9 of both 4046's and tie them to the single wiper of the trimpot or do I test each 4046 one at a time (or using two trimpots)? I'm doing the test right now.

[guitylerham]

Actually, you did. The first way was what I meant. Put it back that way. Once you're there, use your voltmeter and see if turning the pot can make the wiper voltage vary a goodly amount around the middle of the power supply (i.e. 6V). If it can, set it to 6V. If there is, check for reasonably clean audio at the emitter of Q4.

If you have clean audio at Q4, lift one end of R97. This last stops any audio from the lowermost (in the picture) 3004 from getting through, good or not. Now you're only listening to the dry audio through R95 and one set of delayed audio through R94. Oh, and the amplitude modulation from the top LFO, but that's been killed off by lifting R36. With this set up, you should be able to hear some vibrato or flanging, even if slight, as you turn the pot. Well, you will if the 4046 is running correctly and it was the LFO that was hosed.

If you hear no audio at the emitter of Q4, then the 3004 is not passing audio, and either the 4046 or the 3004 is hosed.
If you hear clean audio at the emitter of Q4 and turning the patched-in pot does nothing to the combined sound at the output, then the 4046 is (probably...) making good clocks but is not being modulated by the pot movement, or is running at so high a frequency that there is no delay perceptible.
If both are working OK, you'll hear some kind of flanging/vibrato sound.

Ok, I lifted R36 and R74. Ran two wires from those (pin 9 of each 4046) to the center wiper of the trimpot. One leg of the pot goes to ground, the other to positive. I measured the wiper voltage and adjusted it to 6v. I then got clean audio at the emitter of Q4. I then lifted R97 and listened to the Emitter of Q4 and RE Out this time and still heard clean audio as I adjusted the trimpot. The only effect I noticed was slight single hiccuping and slight volume shifts near the ends of rotation as I kept the pot moving but I never could dial in a constant vibrato effect when the pot was still.

What now? This is pretty exciting, by the way.

[guitylerham]

Ok, well the warbly screeching, laser gun noise is back at the outputs of IC1!!! Grrr, I was hoping that issue wasn't just intermittent! IC4's outputs still sound good and clean. Something is up with IC1 and IC2. Would it help to hear what I'm talking about? I can post a youtube clip later tonight. Very frustrating.

[R.G.]

Ok, I lifted R36 and R74. Ran two wires from those (pin 9 of each 4046) to the center wiper of the trimpot. One leg of the pot goes to ground, the other to positive. I measured the wiper voltage and adjusted it to 6v. I then got clean audio at the emitter of Q4. I then lifted R97 and listened to the Emitter of Q4 and RE Out this time and still heard clean audio as I adjusted the trimpot. The only effect I noticed was slight single hiccuping and slight volume shifts near the ends of rotation as I kept the pot moving but I never could dial in a constant vibrato effect when the pot was still.

The hiccups and volume shifts were from the residual effects of the amplitude modulation, which we did not disable.

Vibrato only happens when the delay time is changing; that is, while the pot wiper is actually changing. Just to be certain, pull up R95 to remove the dry sound. If you still get clean audio, it's coming through the 3004, and so that part is working OK.

You can do this same set of tests by working on the lower 4046/3004 with corresponding parts.

Ok, well the warbly screeching, laser gun noise is back at the outputs of IC1!!! Grrr, I was hoping that issue wasn't just intermittent! IC4's outputs still sound good and clean. Something is up with IC1 and IC2. Would it help to hear what I'm talking about? I can post a youtube clip later tonight. Very frustrating.

Hearing it won't help, but you HAVE accomplished something very worthwhile. You have shown that both paths can pass audio, and that there is an intermittent to track down. "Just intermittent" is cause for celebration - it means that it can work, except for some triviality that's going wrong. Believe me, it's far worse if it's solid dead no matter what you do. 

[guitylerham]

Right on, RG. I'll keep at it. Can't tell you how grateful I am for your effort in helping me out. I'd be stuck in the water without it. 

I'll keep you all posted! This pedalboard is going to be awesome...

[guitylerham]

Update: When my circuit isn't making random noise and is producing relatively clean outputs, I am getting some vibrato effect! Progress! The problem is that the "slow" setting seems to have very fast vibrato and when I activate the "fast" speed, the pulsing speeds up and enters flanging realm until there isn't a good pulse anymore. So it seems to me that the pulsing from the clocks and whatnot is set waaaay too fast. I've read and reread the project thread that I pulled all this from and they mention halving the clock speed to accommodate using the MN3007 instead of MN3004. So instead of the 1N5 clocking capacitor on each 4046 (between pins 6/7), I used a 750pf. Is there another component that yields an effect on pulsing speed to this effect? I don't believe the "Freq Adj" trimpots or associated diodes that govern the pulsing speed are the ones that need to be tweaked. This problem is beyond what they are capable of adjusting.


Also -- from contributors in that project thread:

At emitter of Q4 is the FM(-time)-modulated (high-pass filtered) audio-signal. This signal is also amplitude-modulated by Q5/Q6. To achieve this, the triangle-signal from the LFO is feed via R36 to D1/D2 which are used as something like a sine-converter for the LFO-output. This LFO-signal is fed to the modulation input R31/R32 through C 2x (?). The higher the voltage, the higher the signal...

the mixing section:
It is a virtual-ground summing-amp like it is used in mixing consoles.
So all the signals are mixed together:
1.) the original signal via R95
2.) The bass signal via R97
3.) A part of the treble-signal via R94
4.) And another part of the Treble signal via Q5/Q6

I am not getting any signal from the emitters of Q5/Q6. Only the faintest audio from the bases of those two. Shouldn't I be hearing a signal?

[Thomeeque]

 Congrats to your progress, sounds promissing!

Modulation speed and BBD clock speed are two completely different areas*.

Post some audio sample, maybe it will ring some bells.

I am not getting any signal from the emitters of Q5/Q6. Only the faintest audio from the bases of those two. Shouldn't I be hearing a signal?

No, same as "there is no audio past R95" explained above.

T.

* Modulation LFOs are very interesting subcircuits here. LFO "base" speed is set mainly by C16/R42 values** and is adjusted by voltage at E1 point, network around C17 sets time, shape and range of the "glide" (fluent speed-up and slow-down of the LFO speed).

Worth being simulated:



CX3_LFO.asc (LTspice IV)

** R42 value influences shape of the wave as well, if you want to change speed change C16.

[R.G.]

... it seems to me that the pulsing from the clocks and whatnot is set waaaay too fast. I've read and reread the project thread that I pulled all this from and they mention halving the clock speed to accommodate using the MN3007 instead of MN3004. So instead of the 1N5 clocking capacitor on each 4046 (between pins 6/7), I used a 750pf. Is there another component that yields an effect on pulsing speed to this effect? ...

Well, there's one problem. In circuits like this, the bigger the capacitance, the lower the frequency. You need to double the original cap value to get the speed to halve. So the cap ought to be 3nF (about) for your purposes.

I am not getting any signal from the emitters of Q5/Q6. Only the faintest audio from the bases of those two. Shouldn't I be hearing a signal?

Probably not. Those transistors are being driven as variable resistors to shunt some signal to ground, changing the gain of the mixer a bit. Finding only a very small audio signal is probably correct.