So I have been working on my quarantine family and basically building 10 pedals at the same time. First 8 fire right up. Then I get to my 2 Blueshifts. Both are completely dead. Not a single sound so it would appear I have fundamentally done the same thing wrong, maybe. Built one with stock bypass and one with minimal bypass.
Two quick questions.
1. Is there a mechanical connection between the boards? By that I mean I don't have the boards connected by header pins. I've used a different larger enclosure and have laid them flat.
2. How is the larger board grounded and how does it get voltage? The small board gets grounded and has the 9v connection.
From the looks of some of the previous builds, there are some header pin connections between boards. :-\
Did you use wires where the header pins would normally go?
Yes, the header connections are definitely required! If you're not sandwiching the boards and instead doing them side by side in a larger enclosure, you'd need to run wires between each of the header pin pads. (Some of them are just grounded on one side and used for structure only - but you'd be on your own to figure out which ones, so it's safer to just run all of them.)
It may pick up extra noise though, I don't know. All the wires that would normally be less than half an inch in length are now going to be ~4".
Well I am actually glad to hear this! Easy fix. Thanks.
Well the good news is I have sound. The bad news is no chorus effect. Trimmers and toggles don't change the sound at all. Time to troubleshoot.
Finally dug into this. Swapped out the BBDs but no dice.
Bypass works and when you kick it on volume goes up, LED comes in but no chorus.
Anyone have thoughts on what might be the top few issues?
Quote from: Scruffie on November 08, 2020, 12:53:04 PM
Voltages
;D As soon as my wife is done dragging me around looking for 6 cabinet knobs :o I'll get some. Since there are a gabillion IC's I'm hoping you just want the BBDs or all gabillion?
Quote from: TNblueshawk on November 08, 2020, 03:46:43 PM
Quote from: Scruffie on November 08, 2020, 12:53:04 PM
Voltages
;D As soon as my wife is done dragging me around looking for 6 cabinet knobs :o I'll get some. Since there are a gabillion IC's I'm hoping you just want the BBDs or all gabillion?
After that traumatic experience, I'll let you off with just the BBD's to start ;)
Alright Scruffie, it was so traumatic, should see the price of 6 knobs!, I couldn't read voltages yesterday.
Here are the following voltages: I'll show the range of large fluctuations otherwise I'll pick the halfway point of those that don't have a large fluctuation.
IC3: IC4: IC8: IC9:
1: 0 6.43 6.45 0
2: 3.1 3.1 3.08 3.1
3: .87 0 0 2.97
4: 6.02 3.1 3.09 6.02
5: 6.43 4.5 to 5.9 4.3 to 5.9 6.43
6: 3.08 .5 to 1.9 .6 to 2.0 3.08
7: 2.9 3.72 to 5.05 3.8 to 5.0 3.95
8: 2.9 6.02 6.02 3.97
Bias on IC3 is too low but otherwise, in range.
Next up, companders.
I'm a cruel mistress.
Quote from: Scruffie on November 09, 2020, 08:04:45 PM
Bias on IC3 is too low but otherwise, in range.
Next up, companders.
I'm a cruel mistress.
I don't scare easily ;D
I did have it biased properly per the docs at one point but I think I fiddled with the trimmers after and thus the bias being off on IC3.
IC2: IC11:
1: .95 .78
2: 1.84 1.86
3: 1.84 1.86
4: 0 0
5: 1.84 1.86
6: 1.84 3.07
7: 2.94 3.07
8: 1.84 1.86
9: 1.84 1.86
10: 1.84 3.07
11: 1.84 3.07
12: 1.84 1.86
13: 9.21 9.21
14: 1.84 1.86
15: 1.84 1.86
16: .95 .78
Do you get any tone change when you adjust the switches?
Just checking the BBD's aren't passing audio but static... best way to check that would be audio probe on pin 7/8 of the BBD.
Otherwise, voltages for IC1, 5, 7 & 12.
Quote from: Scruffie on November 10, 2020, 12:40:02 AM
Do you get any tone change when you adjust the switches?
Just checking the BBD's aren't passing audio but static... best way to check that would be audio probe on pin 7/8 of the BBD.
Otherwise, voltages for IC1, 5, 7 & 12.
Nothing changes the tone. Not the switches nor the trimmers. I get no static in terms of when I kick it on but have not probed. I'll get the probe out tomorrow.
When I kick it on there is a slight volume increase and the tone has a slightly brighter tone . But after that nothing changes it.
It reminds me a few years back when say you might get some bad BBDs that pass signal but don't do anything else. I got the Cool Audio and other ICs from Smallbear so I feel they are good.
I'll report back tomorrow.
Ok, so I probed all the IC's actually. First, both BBD's pass zero signal on pins 7 and 8. Quite as a church mouse there. Of the 12 IC's the following are the only pins to pass signal.
IC 1 - pins 2 & 7
IC 2 - pin 5 barely audible but still there
IC 11 - pins 4 & 12
IC 12 - pins 2 & 6.
All other IC's and pins pass no signal or really any noise at all for that matter. No static etc...
Voltage readings:
IC 1: IC 5: IC 7: IC 12:
1: 0 3.77-5.09 .6 - 6.0 ( quite the swing) 4.6
2: 4.6 .9-1.64 3.28 4.6
3: 4.6 1.5 2.1-4.5 4.6
4: 0 0 0 0
5: 4.6 3.31 3.31 4.6
6: 4.6 3.31 3.31 4.6
7: 4.6 2.2-4.5 2.5-4.1 4.6
8: 9.21 6.24 6.62 9.21
Okay, you've gone a bit off course with your probing.
IC2 pin 7 is where you should listen for audio, should be loud and compressed.
Then, assuming that checks out you can follow to Q5 emitter and then pin 3 of each BBD.
If you get signal at pin 3 of the BBD and it wont pass at pin 7&8 with adjustment of the bias trimmer, might have to consider the BBD or clock again.
IC1 pin 1 voltage reading I'm going to assume is a mistake.
So pin 7 on IC2 is dead. No sound. Swapped it out for another Cool Audio V571 no dice.
Yeah that was a mistake. Pin one on IC 1 has 4.6v
Want pics at this point?
Sure, post some up of that area.
Had to step away from this one as I was getting irritated. I decided to reflow all the joints to be sure and then I got static. Went over it again and I had 2 solder bridges that I must have done when reflowing. Now I'm back to where I was. Here are some pics.
I can't imagine trying to figure out the audio path on this thing. Still dead at pin 7 of IC 2 as well as pins 7 & 8 of the BBD's.
Scruffie, I don't expect you to spend a ton of time on this (or any for that matter). Feel free to bail if it is just too deep. I'll just have to lick my wounds and move on from this thing.
(https://live.staticflickr.com/65535/50614261028_51bf6cdd72.jpg) (https://flic.kr/p/2k7BjqU)
(https://live.staticflickr.com/65535/50615113722_400898bcfb.jpg) (https://flic.kr/p/2k7FFUw)
(https://live.staticflickr.com/65535/50615113732_41db1eef17.jpg) (https://flic.kr/p/2k7FFUG)
It's not as complicated as it looks, no different to any other delay circuit really, just everything's split and doubled but to reach the BBD's, the signal must past through IC2.
I see tantalum capacitors, you didn't get them from Tayda, did you?
Maybe get a toothbrush and some alcohol and clean off some of the flux. You might spot something you missed. Also, my build of this circuit didn't work right away either. But, it is well worth the effort. It is a very nice chorus. For what it is worth, my initial attempt had a bad ground wire.
You are missing the two (3 pin) headers in the middle of the boards.
Agree with EBK, you should definitely stick with this one, it's worth it.
Quote from: Bio77 on November 17, 2020, 10:24:00 PM
You are missing the two (3 pin) headers in the middle of the boards.
I was just now wondering about those myself.
Oh, is that what those are for, yeah, that sounds important.
1. I don't recall if I got the tants from Tayda. I got parts from multiple places when I loaded up to build all these. Are they notoriously bad?
2. Holy crap! The middle pin headers :o. I was so focused on the connecting the outside pin headers I didn't see the forest from the trees and looked right past that :-X
Well I'll report back once I connect those.
I once tacked the outside pins on all the sockets on a Rust Bucket and then left it at that. I trouble shot for hours staring at the board to make sure I didn't have any bad solder joints. In my brain I guess I wasn't looking for MISSING solder joints.
So I'm not about to throw any stones :-)
Success! Just about peed myself.
So I fiddled with the trimmers after starting at 3.4v but have a question. Is this a subtle chorus? I ask because the switches change the sound a little but not a lot. Same with the trimmers. I'm wondering if I need to look at some other things to get more 'lushness'.
I realize by separating the boards I sort of created my own monster so I'll own it if by doing that I may have altered things.
Thanks for the sympathy thoughts Gordo ;D
I don't know if I'd call it a subtle chorus pedal, it doesn't really sound like most others. If you have a scope to calibrate the pedal with, that will make it A LOT easier to do. Since this has two BBDs in it, the first BBD is easy to dial in (the pedal starts to chorus) but the second BBD is harder because it's sound gets placed "on top of" the other's chorus sound. If you don't have a scope, I guess the best way to describe it is that when the second BBD gets dialed in, the chorus sound gets "thicker".
A scope makes it so much simpler though ..
Hope this helps
BTW, switch "4" will give you the most pronounced chorus sound. The Blueshift kills when used as a stereo chorus. The "lushness" comes in when used in stereo
Awesome, congrats!
You do need a scope to get it perfect but around 3.2-3.4 sounds right and should give you a nice sounding pedal. Once you get the trimmer above a certain threshold you won't hear a big difference, it will just start to clip when the input is too large.
Not sure I would say this is subtle sounding, but it doesn't have a dramatic warble like other choruses. That's what the two BBDs are all about.
If you don't have a scope, just audio probe pin 7 & 8 of each BBD while adjusting its bias.
Quote from: danfrank on November 19, 2020, 04:10:53 AM
I don't know if I'd call it a subtle chorus pedal, it doesn't really sound like most others. If you have a scope to calibrate the pedal with, that will make it A LOT easier to do. Since this has two BBDs in it, the first BBD is easy to dial in (the pedal starts to chorus) but the second BBD is harder because it's sound gets placed "on top of" the other's chorus sound. If you don't have a scope, I guess the best way to describe it is that when the second BBD gets dialed in, the chorus sound gets "thicker".
A scope makes it so much simpler though ..
Hope this helps
BTW, switch "4" will give you the most pronounced chorus sound. The Blueshift kills when used as a stereo chorus. The "lushness" comes in when used in stereo
Thanks for the explanation as it was spot on.
Quote from: Scruffie on November 19, 2020, 11:23:10 AM
If you don't have a scope, just audio probe pin 7 & 8 of each BBD while adjusting its bias.
I don't have a scope but I think I've got it dialed in real close.
However, what does it mean when I get zero sound out of pins 7 and 8 of the BBD's, IC's 3 & 9?
Quote from: TNblueshawk on November 19, 2020, 04:27:53 PM
Quote from: Scruffie on November 19, 2020, 11:23:10 AM
If you don't have a scope, just audio probe pin 7 & 8 of each BBD while adjusting its bias.
I don't have a scope but I think I've got it dialed in real close.
However, what does it mean when I get zero sound out of pins 7 and 8 of the BBD's, IC's 3 & 9?
That they're not passing signal and you have no effect... when working, you should hear clean undistorted vibrato on each chip there.
Quote from: Scruffie on November 19, 2020, 04:33:13 PM
Quote from: TNblueshawk on November 19, 2020, 04:27:53 PM
Quote from: Scruffie on November 19, 2020, 11:23:10 AM
If you don't have a scope, just audio probe pin 7 & 8 of each BBD while adjusting its bias.
I don't have a scope but I think I've got it dialed in real close.
However, what does it mean when I get zero sound out of pins 7 and 8 of the BBD's, IC's 3 & 9?
That they're not passing signal and you have no effect... when working, you should hear clean undistorted vibrato on each chip there.
I still get no signal from the BBD's on pins 7,8. I can say with 100% certaintly some type of chorus signal is passing through. Can't tell you how but when you click it on an off there is a audible difference but that explains my subtle comment earlier. I also get no signal from pin 7 of IC 2. I do get signal from a few other spots that I mentioned earlier in the thread so I know my audio probe works.
Scruffie, could a tant cap issue be the problem?
The signal always passes through a pre/de-emphasis network, while they're supposed to be neutral, they pretty much always audibly impact tone, so that could be what you're hearing?
The signal has to pass through IC2 pin 7 to reach the BBD's and the output of the BBD's is pin 7&8, if your audio probe is definitely working and there's not something weird going on, you can't possibly have any modulation.
Could a bad cap on the compander be the cause? Possibly... I mentioned Tayda tantalum capacitors because last time I tried to use one for digital power filtering it ended up injecting noise rather than removing it and I've avoided them since, I've also heard of their electro's simply being shorts.
Signal comes from IC1 pin 7, goes in to the companders input at pin 6, comes out at pin 7.
Ok thanks. I'll be out of town for the next several days so I'll pick back up on it then. Thanks Scruff.