# VIIB Build



## slowpogo (Jul 20, 2021)

I don't know if anyone else went ahead and built their VIIB even before build docs are posted...well I couldn't wait! Without biasing instructions I'm just guessing but I've got it in a place where distortion is minimzed and the vibrato happens _sometimes _(see below). Running at 9V, it draws 10-12mA. I'm testing with Depth turned up pretty high and Rise Time turned down. Here are a few initial issues..

- I get sound in bypass, then volume jumps up 5-6db when pedal is "On"
- LED does not light at all. Using what I thought was the recommended red/blue one from Small Bear, still works when testing with my multimeter
- only time I hear the vibrato effect is if I turn the Rate knob up from full CCW, then the vibe comes in briefly (and sounds great!) but quickly flattens to a regular signal

Only substitution is a 500k trim instead of 470k. BBD is a Panasonic MN3207 from Banzai Music (text is very faded). Clock is an MN3102 I stole from a previous build so I know it works. I'm using the posted footswitch and the relay bypass system does seem to work, in that it will latch on/off with quick taps, but is momentary with longer hold times. I'm not sure how to switch between True Bypass and Classic modes.

No expectation of comprehensive help at this early stage of the board's availability but if anyone wants to chime in that'd be great.


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## Robert (Jul 20, 2021)

Hmmm...  OK, lets get the simplest thing out of the way first, because it's also a good indicator of whether the digital portion is working properly or not.    You did say the relay bypass was switching on/off, so that's a good sign.

Can you confirm that the dual LED is common cathode?


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## Popnfreshbass (Jul 20, 2021)

I’d beware of Banzi stuff. I’ve gotten burned by them before. If you have a spare v3207 in a chorus or something try putting that in too see if it works


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## Hirti (Jul 20, 2021)

Popnfreshbass said:


> I’d beware of Banzi stuff. I’ve gotten burned by them before. If you have a spare v3207 in a chorus or something try putting that in too see if it works


I also bought two MN3008 on their website a few years ago that turned out to be fake…


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## slowpogo (Jul 20, 2021)

Robert said:


> Hmmm...  OK, lets get the simplest thing out of the way first, because it's also a good indicator of whether the digital portion is working properly or not.    You did say the relay bypass was switching on/off, so that's a good sign.
> 
> Can you confirm that the dual LED is common cathode?


The LED is common cathode, it's part 2306B from Small Bear.



Popnfreshbass said:


> I’d beware of Banzi stuff. I’ve gotten burned by them before. If you have a spare v3207 in a chorus or something try putting that in too see if it works


I tried a working 3207 from my Low Tide build and got the same behavior. I've actually not had any problems with Banzai but it's good to know others have.


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## fig (Jul 21, 2021)

slowpogo said:


> I've actually not had any problems with Banzai but it's good to know others have.


It seems to be hit or miss with them, which could equate to unreliable suppliers and/or QC.


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## Stickman393 (Jul 23, 2021)

Takmans, PRPs, look at all dem pretty resistors.


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## Robert (Jul 23, 2021)

Hold down the footswitch while applying power, this will switch the pedal to Buffered bypass mode.

See if the LED lights then.


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## fig (Jul 23, 2021)

Alternatively, you could close your eyes and click your heels 3 times...

...this puts YOU in buffered bypass mode.


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## slowpogo (Jul 23, 2021)

Robert said:


> Hold down the footswitch while applying power, this will switch the pedal to Buffered bypass mode.
> 
> See if the LED lights then.


Tried this. The LED does not light after switching, but the volume is now consistent between on/off in the new mode. Otherwise the behavior is identical.



Stickman393 said:


> Takmans, PRPs, look at all dem pretty resistors.


People disagree about resistors having a "sound" but I'm convinced Takman carbon films do actually warm up the signal path, in a nice vibey way.


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## Robert (Jul 23, 2021)

That's puzzling....   The microcontroller is switching, otherwise the relay wouldn't latch/unlatch...  

I can't think of any reason the LED wouldn't light aside from it being the wrong type.    Can you measure the DC voltage on the R and G pads of the LED in Active and Bypassed mode?

You can do this with the upper analog board disconnected and out of the way.   The digital board will function without it.


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## slowpogo (Aug 3, 2021)

Finally getting back around to this! Life got hectic, as it sometimes can do. I did this test with the analog board detached.

Bypassed (draws 2ma)
G = 4.01v
R = 0.01v

Active (draws 3ma)
G = 0.02v
R = 4.98v

I clipped out the LED to test with my multimeter. Putting my red probe on the center leg, it will light when I touch the outer legs with the black probe. But not the other way around. Which means it's common ANODE, right? Darnit.

This is actually Small Bear's mistake, at least as the order is concerned. I ordered the common cathode part and that is what's on my invoice, but they sent this one. I'll see if they can send a replacement, never had to test their customer service like this before.

LED aside, what might be causing the other bad behavior?


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## slowpogo (Aug 9, 2021)

any estimate when we will get build docs, or at least a schematic for this? I don't think I can debug it without the schematic.


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## Robert (Aug 9, 2021)

I'll be working on more build docs later today.   This is one of the next ones on the list.


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## Robert (Aug 10, 2021)

Here's the schematic / component layout.    This doesn't include the parts list, wiring diagram, or drill template yet, but should be what you need.

https://docs.pedalpcb.com/project/VIIB-PedalPCB-Preliminary.pdf

I would start by ensuring that the LFO is present on pin 9 of the LM13700  (turn Rise to minimum so it isn't lagging).


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## slowpogo (Aug 10, 2021)

Great! thank you


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## zombie_rock123 (Aug 10, 2021)

Sorry to chime in without help on a troubleshooting thread but massive thanks to Pedalpcb for the doc, I've got dry signal but no chorus with tested BBDs so this will hopefully help solve


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## slowpogo (Aug 10, 2021)

Robert said:


> I would start by ensuring that the LFO is present on pin 9 of the LM13700  (turn Rise to minimum so it isn't lagging).


I'm getting a variable voltage reading on pin 9 (fluctuates up and down). which I'm guessing means the LFO is present?

I can't figure out why the vibe would be there just like I expect, then quickly flatten out. A short, somewhere? The board looks good and clean. My only idea at this point is to go step by step through the schematic and check continuity on everything.


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## Wizardofwoz66 (Sep 16, 2021)

Is there enough room on this to socket the ICs? I always install sockets first and didn't want to do it if not


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## slowpogo (Sep 16, 2021)

Wizardofwoz66 said:


> Is there enough room on this to socket the ICs? I always install sockets first and didn't want to do it if not


Yes, in fact there are several pictures above demonstrating this 

btw I still haven't gotten this to work. Pretty much given up on it at this point


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## slowpogo (Jul 20, 2021)

I don't know if anyone else went ahead and built their VIIB even before build docs are posted...well I couldn't wait! Without biasing instructions I'm just guessing but I've got it in a place where distortion is minimzed and the vibrato happens _sometimes _(see below). Running at 9V, it draws 10-12mA. I'm testing with Depth turned up pretty high and Rise Time turned down. Here are a few initial issues..

- I get sound in bypass, then volume jumps up 5-6db when pedal is "On"
- LED does not light at all. Using what I thought was the recommended red/blue one from Small Bear, still works when testing with my multimeter
- only time I hear the vibrato effect is if I turn the Rate knob up from full CCW, then the vibe comes in briefly (and sounds great!) but quickly flattens to a regular signal

Only substitution is a 500k trim instead of 470k. BBD is a Panasonic MN3207 from Banzai Music (text is very faded). Clock is an MN3102 I stole from a previous build so I know it works. I'm using the posted footswitch and the relay bypass system does seem to work, in that it will latch on/off with quick taps, but is momentary with longer hold times. I'm not sure how to switch between True Bypass and Classic modes.

No expectation of comprehensive help at this early stage of the board's availability but if anyone wants to chime in that'd be great.


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## Wizardofwoz66 (Sep 16, 2021)

slowpogo said:


> Yes, in fact there are several pictures above demonstrating this
> 
> btw I still haven't gotten this to work. Pretty much given up on it at this point


Sorry to be that guy 😅 I'm using my phone and somehow I missed like the top 3/4s of this thread, my apologies. Best of luck with it! I'll report back once I've built mine


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## Stickman393 (Sep 17, 2021)

Double check your c22 & C23 values?

check C8 while you're at it too...

Gut feeling?  Sounds like an undersized cap.  Maybe.  I dunno, my gut's got shit for brains.  Fwiw.

Take IC voltages and I'll hook ya up with my own...compare/contrast, mine fired up on the first go.


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## slowpogo (Sep 17, 2021)

Wizardofwoz66 said:


> Sorry to be that guy 😅 I'm using my phone and somehow I missed like the top 3/4s of this thread, my apologies. Best of luck with it! I'll report back once I've built mine


No worries, I've done the same. Just in a facetious mood   



Stickman393 said:


> Double check your c22 & C23 values?
> 
> check C8 while you're at it too...
> 
> ...


Thanks! I'll check this when I get a chance


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## slowpogo (Sep 18, 2021)

Stickman393 said:


> Double check your c22 & C23 values?


Turns out my C23 was a mislabeled Russian cap. Although it was actually an oversized cap, it was 470n instead of 47n! I got it in a grab bag from some Russian transistor seller on ebay...foolish not to check it first. I thought I'd add some "Russian mojo," and I guess I did in a way  Thank you Stickman, I was running out of motivation and it would have been awhile til I found that myself, if at all.

So it basically works now! And being someone who can't be satisfied for even a moment, I immediately have a complaint lol. I'm disappointed that the lowest Rate is about 2 Hz. For some reason I had it in my head that it got much slower.

Would it be possible to shift the entire rate range downward? or somehow make the lowest rate something like 0.5 Hz or even slower, by changing some values? I'd love to get a barely perceptible, drifting cassette tape kind of sound.


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## slowpogo (Sep 18, 2021)

I didn't try messing with the trims yet -- I realized they might affect the rate range(?). I'm still not entirely sure what the trims do without docs but I'll give that a shot.


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## Stickman393 (Sep 18, 2021)

Got ya covered here:

These photos were NOT particularly easy to find on the interwebs.


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## Chris411 (Oct 6, 2021)

slowpogo said:


> The LED is common cathode, it's part 2306B from Small Bear.
> 
> 
> I tried a working 3207 from my Low Tide build and got the same behavior. I've actually not had any problems with Banzai but it's good to know others have.


I would note here that I ordered a Common Cathode LED from small bear, but what arrived was actually Common Anode when I tested it.


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