Blue Yonder Schematic Question

[jdduffield]

I am attempting to build a Blue Yonder from the schematic. For Q1 and Q2, I’m using 2SK30A JFETs. I’ve noticed it is working, but quieter when the pedal is engaged in comparison to it being bypassed. Is there a resistor value I can swap to affect output volume?

Also, leg 1 of these trim pots go to ground, right? (See photo)

 

[jdduffield]

Just a follow up. I put a booster circuit in front of it, which has a single transistor boost to bring the overall volume up. What I’m noticing now is that the gain control never did work properly. When the gain is all the way down I hear nothing (which is as it should be). However, when I turn the gain up about a quarter of the way, I get a clear output, but then any position above that “audible but clean” position sounds exactly the same both in terms of crunch and volume.

 

[jdduffield]

Another question I have is around the JFET legs. Is the 1, 3, 2 meaning the leg number? (See photo) I think it does and I have the legs of the JFETs like this, where leg 2 and 3 are swapped. (See photo)

 

[anevilspar7an]

Unswap the legs of your JFETS, the board is laid out for the correct pinout.

 

[bluedmc777]

Are you saying the pedal is quieter engaged but you failed to say where your volume and gain levels were set. I assume you mean it’s quieter even with both maxed? Can you not reach unity gain? Did you bias the pedal?

 

[jdduffield]

Are you saying the pedal is quieter engaged but you failed to say where your volume and gain levels were set. I assume you mean it’s quieter even with both maxed? Can you not reach unity gain? Did you bias the pedal?

Yes. Both maxed. I tried biasing both to 4.5v. I’m not used to JFETs and I think maybe that is my issue. I tried different JFETs and the result is the same. I tried the rat ones, and various 2SK30s. I tried reflowing the solder on everything.

The post above says the legs don’t need to be swapped, but maybe I wasn’t clear that this is on protoboard, not a PedalPCB circuit board. I just wanted to try building a simple overdrive and downloaded the schematic and went from there.

I’m also using P90s in my guitar which has a low output volume to start. I’ve been wondering if maybe my circuit is working but just doesn’t sound good because of the guitar I’m using.

 

[bluedmc777]

Were the jfets you initially used the same as the ones listed on the BOM? If not did they atleast have the same pin layout? If yes to either of those I wouldn’t think you’d need to swap the pins.

The Blue Yonder really doesn’t have a lot of output. I can dime the level on mine with the gain down low and still be just above unity gain from what I remember. Also, try biasing to where the pedals sounds good to you if you’re having trouble until you figure out what the issue is. Don’t expect Alot of gain out of the pedal though.

 

[Nostradoomus]

Where did you get the 2sk30s? You can get the proper 2sk208-R at mouser, albeit in an SMD package.

 

[Feral Feline]

...

Also, leg 1 of these trim pots go to ground, right? (See photo)

No, the pot is wired as a rheostat, not a voltage divider. Leg 1 is not connected to anything.

It's good practice to not leave the leg floating, though, that way if the pot's wiper fails for some reason, the pot would go to max resistance;
so you would/could/should tie leg 1 to leg 2, in this instance.


Can we get some pics of you build? (use lots of light)
Also a copy of your layout would be helpful in the troubleshooting procedure.

 

[jdduffield]

Where did you get the 2sk30s? You can get the proper 2sk208-R at mouser, albeit in an SMD package.

I’m not sure but I think Amazon.

 

[jdduffield]

Can we get some pics of you build?

I’ll try to remember to do that tonight.

 

[anevilspar7an]

I’m not sure but I think Amazon.

Just going to say never trust transistors off of scamazon, they will almost always be something else.

 

[anevilspar7an]

You can sub in a J201, just mind the pinout. Another option is to grab some 2SK208 from here: Aion FX, Kevin over there is a reputable source of what parts he can get.

 

[jdduffield]

Just going to say never trust transistors off of scamazon, they will almost always be something else.

I actually agree with this. I’ve started buying from mouser. These particular ones I purchased as a noob years ago.

I will say though, when I put the Rat JFETs in, which are from mouser, the results were the same. So, I think I’ve got something wrong with my circuit build.

 

[jdduffield]

I need to buy a DCA Pro to test JFETs. Just haven’t done it yet.

 

[jdduffield]

Can we get some pics of you build?

I imagine it will be too difficult to tell the issue from photos, unless it is glaring. Also, the little black board is an output booster that I added after the fact, hoping it would help. It brought the volume up, but didn’t solve anything as the gain pot was still not doing hardly anything.

 

[Feral Feline]

I was expecting a vero layout...


Hoo boy, that is ... daunting.
Not impossible, but certainly difficult.


Do you have the DIYLC program? That would enable you to draw up a copy of that particular board with its layout.

OR you could photo-shop the backside of the board onto the front (layered and flipped so it matches) and then we could see what's connected to what.


Also, curious... why did you specifically choose to put the boost before the main circuit?
If you wanted the main circuit's sound, only louder, it'll work better putting the boost after the main circuit.

 

[Nostradoomus]

 

[jdduffield]

I was expecting a vero layout...


Hoo boy, that is ... daunting.
Not impossible, but certainly difficult.


Do you have the DIYLC program? That would enable you to draw up a copy of that particular board with its layout.

OR you could photo-shop the backside of the board onto the front (layered and flipped so it matches) and then we could see what's connected to what.


Also, curious... why did you specifically choose to put the boost before the main circuit?
If you wanted the main circuit's sound, only louder, it'll work better putting the boost after the main circuit.

Not sure if the juice is worth the squeeze. I may just retire this to the box of “not working” experiments… and try again later.

 

[Locrian99]

save yourself the headache and order the board. When i first started I did vero builds, i realized why when there is a board available hell if its not I just lay one out in diptrace and order it now. Vero is too time consuming to save a few bucks. Support the guy who traced the schematic for you too.