Fraudhacker De-Bug Help - I'm Stumped

[Bio77]

My Fraudhacker build was working.  Biased perfectly, clock freq good.  Played through my amp and it sounded good.  Started messing with the T1 trim to set the upper feedback limit and started getting weird clicks at different spots on the Manual knob.  The clicks got worse and flanging stopped.

My first thought was that I had a bad T1 trim.  I took it apart today and replaced the T1 trim.  Voltages all look good except maybe the TL022 where I get:

1 Varies
2 2.84
3 2.83
4 0
5 Varies
6 2.81
7 5 or 0.63 (switches)
8 5.66

I'm not sure if I was in the working or non-working mode when I got these voltages (see below).

I tried a few different TL022s and a TL062.  While switching the LFO chips I noticed that it starts to work and then reverts back to the clicking and loses flanging.  Now I realize that if I unplug the effect and/or twiddle the knobs a bunch I can sometimes get it fired up.  My last experiment I had a working pedal again and it only started clicking when I messed with the knobs a lot. 

Any ideas would be much appreciated 

[blackhatboojum]

Whoa.  Ok this is weird one.  The voltages you currently have listed on the TL022 are all spot on, including the one that switches. That's how they should look in working condition.  I've had one too many whiskey and cokes to be of much more help tonight but, I'll revisit this tomorrow.

[Thewintersoldier]

I would try audio probing. Could be a bad cap somewhere. It's happened a couple times to me so worth a try, even when my voltages looked good.

[blackhatboojum]

What are your voltages looking like on pins 5&7 and pins 2&4, on the mn3102 when the effect dumps out and quits working?

[Bio77]

What are your voltages looking like on pins 5&7 and pins 2&4, on the mn3102 when the effect dumps out and quits working?

I plan to do a working and not-working voltage measurement latter today.  Will report back.

I would try audio probing. Could be a bad cap somewhere. It's happened a couple times to me so worth a try, even when my voltages looked good.

I was thinking cap too, maybe the intermittent behavior is limited by a cap charging and discharging.

Other notes: I have a 3204 in there for the HF-2 mod. I have working 3204 BBD builds and have already tried subbing the chips from those in the new build, still doesn't work.  Also I have JRC 2068Ds instead of the 4558s.  Typically use these in flange and chorus builds but thought it was worth mentioning. I'll try swapping those later, as well.

[Bio77]

A mixed update:  I identified the problem but am still confused 

I hooked up a guitar and amp to the PCB to make sure that it was in the problem state while I took voltages.  In problem state I got a lot of weird varied voltages on IC3 (pins 2,3,6 and a little variance on 7 and 8 ) and IC4 (pins 2,4,5,6, &7).  While taking the voltages I noticed that I could switch it from the problem state to functioning by probing pins 2 and 3 of IC2, respectively.  Very repeatable behavior, if I probe pin 2 of IC2, I have a working pedal; If I probe pin 3, non-working. The switching between states is like a switch, meaning that after I probe the respective pin it is in that state after I remove the probe. 

Anyway, I had a JRC2068 in IC1 and IC2.  I switched IC2 back to a 4558 and now the pedal is working. Here are my questions:

1.  WTF? Please theorize on this weird bi-modal behavior 
2.  Was the 2068 bad or did having one there in the first place cause this? Only difference I can see in the data sheet is that 2068 can run at higher voltages and has better S2N that 4558 (which is why I usually use them in chorus and flangers).
3.  Should I keep the 2068 in IC1 or also switch it to a 4558?

[mauman]

A 2068 is lower noise than a 4558, but isn't as stable at high gains, has a lower input Z, and will oscillate if the resistive load is too low, or if the capacitive load is too high.  This circuit was designed around the 4558, looks like, not the 2068.    Probing the 2068 in IC2 probably pushed it over the boundary into/out of oscillation.  It may or may not show problems in IC1 if you leave one in there.     

[blackhatboojum]

A mixed update:  I identified the problem but am still confused 

I hooked up a guitar and amp to the PCB to make sure that it was in the problem state while I took voltages.  In problem state I got a lot of weird varied voltages on IC3 (pins 2,3,6 and a little variance on 7 and 8 ) and IC4 (pins 2,4,5,6, &7).  While taking the voltages I noticed that I could switch it from the problem state to functioning by probing pins 2 and 3 of IC2, respectively.  Very repeatable behavior, if I probe pin 2 of IC2, I have a working pedal; If I probe pin 3, non-working. The switching between states is like a switch, meaning that after I probe the respective pin it is in that state after I remove the probe. 

Anyway, I had a JRC2068 in IC1 and IC2.  I switched IC2 back to a 4558 and now the pedal is working. Here are my questions:

1.  WTF? Please theorize on this weird bi-modal behavior 
2.  Was the 2068 bad or did having one there in the first place cause this? Only difference I can see in the data sheet is that 2068 can run at higher voltages and has better S2N that 4558 (which is why I usually use them in chorus and flangers).
3.  Should I keep the 2068 in IC1 or also switch it to a 4558?

Oh wow.  Yeah, this is definitely weird.  My initial instincts where pointing to a clock issue based on what you described.  I thought is was odd that adjusting the resonance trimmer would cause the delay chip to dump out though.  I think mauman is onto something with the 2068 going into oscillation and causing the problem but, this is starting to get beyond my knowledge of electronic components so, Imma have to bow out at this point on theorizing.  Nice job on figuring it out though John  . 

[Bio77]

So, I switched both IC1 and IC2 to the 4558 to be on the safe side.  I'm going to test the pedal out for a few weeks and see if the problem returns. 

Thanks for the input and encouragement! 

[Bret608]

John, I'll be watching this closely for sure--my CS-9 build is still behaving intermittently despite switching out the TL062 for a TL022, trying out multiple FETs in the gate (which you kindly shared with me), and otherwise pulling out my hair since the thing sounds amazing when it's having a good hair day. Besides a possible bad cap or something, the 2068 was about the only thing I had left to wonder about since it's the only one where I don't know how the voltages should look. When things go wonky, it just stops passing signal other than a faint static noise.

[Bio77]

Do you have a 2068 in your CS9 build? 

Update on my Fraudhacker:  Used it yesterday for some band action for ~3h.  Ran like a champ and sounds amazing.  Brian is a wizard recently with low noise.  Both the new Collosalus and this one are dead quiet, which for flanger fans is a feat. 

[Bret608]

I do indeed have a 2068 in there. Sounds like swapping it may be a good idea, based on how things went with your pedal in a full band practice! 

[jimilee]

I'm just looking at your switch soldering, does lug 4 have any solder on it? That's the lug that would send audio to your board.

[Thewintersoldier]

Do you have a 2068 in your CS9 build? 

Update on my Fraudhacker:  Used it yesterday for some band action for ~3h.  Ran like a champ and sounds amazing.  Brian is a wizard recently with low noise.  Both the new Collosalus and this one are dead quiet, which for flanger fans is a feat.

I'm glad you got the flanger working. How awesome is that mn3204 in the fraudhacker??!!

[Bio77]

I'm glad you got the flanger working. How awesome is that mn3204 in the fraudhacker??!!

Just one session to report, but absolutely loved it  .  Big thanks to you, Chris, for starting this journey. 

The BF-2 has been a big part of my bass sound for a long time.  Once I got into pedals I started building and trying all the flangers.  I've been using DeadEnd FX Flange-a-rama (Ibanez FL-99) since ~2018, which has switchable one or two 3402s (i.e., you can choose 512 or 1024 stages on the BBDs).   When you started this HF-2 idea, it kind of clicked for me that I could have what I like about the FL99 in a BF-2. 

I have built several BF-2s on a board Felix made for me as a BOTY prize a few years back.  But I was planning to build Brian's BF-2, anyway.  The LFO noise when not playing is a big pet peeve of mine and after building the new Collosalus I figured Brian wizard-ed away the noise in this one too   .  I took some liberties and moved the output jack to a more traditional spot.  Probably wouldn't recommend that change in retrospect.  You can see in the layout how the LFO is isolated and as far away from the jacks as possible with top-mounts. I got burned on my mods this round and I've learned my lesson