Aion Refractor B100K dual gang issue

[rmsmarr]

Hello

I've just completed a new Aion Refractor build with the switch PCB included for a 125b enclosure.  Everything seems to be working fine except the operation of the gain control.  At zero to the left it's full gain as I turn clockwise moves to clean tone. Is that the way it's supposed to be?   I've got them in backwards before.   According to the PCB Board and the Drilling template there is only one pin orientation for placement and it would be impossible to reverse the pot. 

Any help appreciated.

[bluebunny]

Welcome!

it would be impossible

Anything is possible around these parts.      Got any pictures?  We'd love to see them.

[Laguna]

It sounds like the pot is backwards
If it doesn't fit backwards, you can solder some wires so you have room

[rmsmarr]

Thanks.
  I believe it is backwards and I'll have to use a dual gang with solder lugs to correct it.  I was hoping someone else had worked the board and could confirm the error.

[EBK]

Did you solder the pots to the wrong side of the board?  I've built a Refractor, and nothing operated backwards when I fired it up.

[mth5044]

Did you solder the pots to the wrong side of the board?  I've built a Refractor, and nothing operated backwards when I fired it up.

That seems like the only way it'd be backwards.

I believe this 125B refractor is a new layout, so perhaps different than one you have built!

OP have you contacted Aion?

[aion]

After I saw this I cross-checked my prototype and went back through the PCB design files. Everything is as it should be, so it's not a layout issue.

In any case, I haven't seen this particular issue before and am not sure how it could be caused by a mistake during building, especially since it uses PCB mount pots (so only one pot orientation & no wiring). I would want to be 100% sure that the problem description is accurate. For instance, there could be an issue with the clipping diodes or something else in the drive section that is making it sound clean, and maybe the full-clean setting has higher relative volume, so it ends up sounding more gainy in comparison.

This is just a wild example - but I think we're beyond obvious solutions so we might need to get creative. Even a broken pot can't really display characteristics of reverse wiring, so I would be surprised if a pot swap fixed the issue.

[bluebunny]

At this point it seems we are now speculating without any real data.  Kevin has suggested that the layout is proven to be good.  Time for pictures to see what you've actually built and perhaps a visit to the sticky "Debugging" thread for some real numbers.

[rmsmarr]

Update: 

I've pulled the pot and checked it out of the circuit.  It is functioning as it should.     I measured the voltages on the ICs and they all seem to be with in spec.   Although,  it was not distorting as it should .  I will be meticulously checking all the part values  and especially with the gain stage.

Thanks

[rmsmarr]

Replaced the diodes with Russian D series.  Rethinking the issue.  Maybe the pot is working as it supposed to.  It's my understanding that as you turn the gain up with the dual gang pot it mixes more distortion and less clean signal.   Maybe I hearing boosted clean and as  I turn the gain up it gets softer because the distortion isn't kicking in so I think the pot is working backwards and maybe its just the distortion signal not kicking in.  I again checked all of the on voltages on the three ICs and they are all spec.  Any Ideas about tracing the gain signal on the board or where it might be failing would be appreciated.

Thanks

[Tony Forestiere]

It's my understanding that as you turn the gain up with the dual gang pot it mixes more distortion and less clean signal.   Maybe I hearing boosted clean and as  I turn the gain up it gets softer because the distortion isn't kicking in so I think the pot is working backwards and maybe its just the distortion signal not kicking in.

That sounds like a perfectly plausible scenario.

[Slowpoke101]

Check the polarity of C16. It is usually a 1uF Tantalum capacitor and it is very easy to install it incorrectly.
It can cause some very odd problems and I wouldn't be surprised if this is the problem.

[thermionix]

Check the polarity of C16. It is usually a 1uF Tantalum capacitor and it is very easy to install it incorrectly.
It can cause some very odd problems and I wouldn't be surprised if this is the problem.

Yep LOTS of Refractor threads with this problem.  Not the Refractor's fault, though.  Tantalums have the positive lead marked instead of the negative, like you usually see with aluminum electros.  There is a + sign, but the printing is so small you'd miss it if you didn't know.  Also tantalums are much less tolerant of reverse voltage, so they might fail completely instead of just sounding a little off.

[rmsmarr]

I replaced C16 with a tested value Tantalum cap and placed the longer lead marked with  + to positive square marked hole.  Should I look at other caps in the gain stage?  Any usual suspects besides C16?

[Slowpoke101]

Have a browse through this thread;
https://www.diystompboxes.com/smfforum/index.php?topic=119579.0

It does cover testing the distortion stage with an audio probe and checking circuit connectivity around the dual gang pot. The thread is rather long and does ramble but it may help.

The centaur circuit can be a pain to troubleshoot as a fault in any one stage can effect other stages. But it can be sorted out and makes for a very nice sounding pedal.

[rmsmarr]

Well:

The dual gang is responding properly now.  I replaced some caps and re-flowed all of my solder joints and made sure there were no bridges.  Voltages on the ICs are to spec.  I'm using Russian D series diodes with a forward of .29.   When I turn the gain up there does not seem to  be much crunch if any.   It's more like a booster with a little color.   Any Ideas why I'm not getting a lot of crunch?

[tedsorvino1]

Depends what do you mean by crunch...
I mean, Klon is used mainly as a fantastic (not so clean) booster or a great foundation drive (1st- 2nd stage).
But still it has a good amount of gain for crunch. But no way something really driven.
Keep in mind that it works better with a driven tube amplifier.
I 've built a refraktor a year ago, and it's always on as a first stage gain. I 've also tried KTR and Soulfood.
All really good pedals.

[EBK]

When I turn the gain up there does not seem to  be much crunch if any.   It's more like a booster with a little color.   Any Ideas why I'm not getting a lot of crunch?

Booster with a little color is a pretty good description, from my limited experience with the circuit.  Don't go cranking that gain up all the way looking for crunch though.  It is better used as a marinade than as a finishing sauce.   

[rmsmarr]

I'm running it thru a fender princeton using a tele.  It's not getting anywhere near the crunch I've seen on youtube demos.

I ran a signal thru the pedal and used a a tracer on IC 1 & 2

On IC1 I got solid tones on every pin except 4 & 8

On IC 2  I only got solid tones on pins 1 & 7

I had all pots turned maximum clockwise

Still not hearing any distortion.  Where I'm hearing tones they are soild and clean.

[thermionix]

I have similar-Vf Russian D9Es in my Refractor, and it definitely gets dirty.  Less than a tube screamer, and totally clean with the gain knob down.  I'm not using hot pickups, just standard P-90/PAF types.