Request for help on AION Refractor build

[Stickman393]

Hey all.  Stickman here.  HVAC TECH by day, prolific chaos generator basically the rest of the time.

Speaking of which,  I have an AION Refractor Klon clone on my bench right now that has me stumped.  I built it from a kit, carefully checked and double checked component values, checked and double-checked polar orientation, re-flowed all the joints, struck the circuit board with my forehead in an attempt to show dominance.

No dice.  I'm at the end of my technical skill.  Halp.

Here's the symptoms:

When the e-switch is set to true bypass and the pedal is OFF, everything is gravy.  Cause it's just jack to jack.  So at least that's good.

When the e-switch is set to buffer bypass and the pedal is OFF, I notice a significant drop in volume and a the guitar takes on a  lo-fi grainyness.

Switch the pedal ON, and the signal gets even weaker, is slightly more distorted, but it still retains the grainy, lo-fi character from the buffer bypass mode.  The knobs...work....ish.  Sorta. Unplug the input jack and the thing squeals.  Cool.

So....looking at the schematic...my attention has been on the components surrounding IC1, as this is the common point between the buffer bypass and the effect output. 

THAT'S NOT TO SAY THAT I HAVEN'T FLAILED A LITTLE BIT.
Here's what I've done so far:

Replaced R1, R2, RPD, R26, R27, & R29.  Also, C1, C2, C3, C5, C17 through 22.

Also: IC1, 2, AND 3.  I also gave it my blood, mostly in an appeal to the dark gods of metal.

I measured everything after I pulled it: everything was within spec.  I also traced out the connections point to point with my meter...nothing out of the ordinary.

Here's my IC VOLTAGES, all taken in VDC
IC1:
1: 4.58
2: 4.58
3: 2.73 (decreases from a starting value of 3.73, used MAX function on meter to determine starting value)
4: 0v
5: 4.56
6: 4.57
7: 4.50
8: 9.11

IC2:
1: 4.58
2: 4.57
3: 4.57
4: -8.83
5: 4.57
6: 4.58
7: 4.58
8: 16.62

IC3:
1: 9.11
2: 4.63
3: 0
4: -4.34
5: -8.83
6: 4.24
7: 5.75
8: 9.11

FOR REFERENCE, these are the voltages AION has posted previously for a fully operational unit:

IC1 - TL072
1 = 4.49
2 = 4.49
3 = 3.54 stable, 3.95 initial (cap charge bleeding down through the meter)
4 = 0.00
5 = 4.49
6 = 4.49
7 = 4.49
8 = 9.00

IC2 - TL072
1 = 4.55
2 = 4.49
3 = 4.49
4 = -8.59
5 = 4.49
6 = 4.49
7 = 4.44
8 = 16.23

IC3 - TC1044SCPA
1 = 9.00
2 = 4.59
3 = 0.00
4 = -4.22
5 = -8.59
6 = 4.09
7 = 5.59
8 = 9.00

Pin 3 on IC1 sticks out like a sore thumb.


Any guidance, ideas on where to start looking, would be appreciated.  THANK YOU!!

[duck_arse]

hello, and welcome to the forum.

how many refractor threads do we have now? it's always nice to include the build docs FOR YOUR BUILT VERSION, and circuit diagrams, etc, otherwise people lose interest, look elsewhere.

IC1 pin 3 will read low because of meter loading on the 2M bias resistor. your measure is fine. however. your R28 value neeeds rechecking - it might have changed from the version docs I have local. it might very well be putting the crimp on your day.

[antonis]

how many refractor threads do we have now?

IMHO, already far more than enough..

[dilettanti]

I was planning to make a very similar post when I get home Monday. I just finished a Refractor build (from the kit), and like yours, it bypasses just fine - but I get no signal at all in buffer mode or when the footswitch is engaged. There's a bit of static, that gets louder as each pot is turned up. My IC voltages all seem fine (all about 10% lower than the values listed in the build docs, but I measured with the gain knob turned down). I've triple checked for solder bridges, and all resistors seem reasonably close to spec. Diodes and caps are properly oriented. I know I still have a lot of diagnostic work to do, but I predict I'll be begging for help.

[Stickman393]

10-4, good point re: build docs.  Shoulda thought of that.  Attached.

I noticed...re: # of refractor threads.  I had looked through the previous posts before I posted...negative.  nada.  Coulda missed something, but hey, I'm here to learn.  You want an exiting topic, I got a DC-2 clone that's 99% done...just...uhhhhhh...trying to figure out how to cleanly tie all the grounds together with my gigantic fingers.  I'm pretty sure that one's rigged to explode as soon as I plug it in.

[idy]

Wow, lots of replacing. So sorry. You are right that problem probably is at/around IC1a.

No need to replace, but confirm values for R3 and R4, another path to ground (with C2) for signal.

I would suggest a signal probe (instrument cable with cap in series on hot lead, alligator clip to ground, plug into cheap small amp, plug a looper into input of pedal, begin probing. You are right that the problem probably is at/around IC1a. Until the buffer is working, no point poking around elsewhere. This could be as simple as a bad/missing ground wire!

Re: your DC-2: With lots of grounds just solder all together with one "extra", cover with shrink tube or tape, the one extra you attach to your best ground (probably a jack.) Some folks like to attach them all to a star lock washer instead and have that go around a jack.

[Stickman393]

A'ite, I may be on to something here.

I'm trying to think outside the box here...I noticed that my footswitch daughter board is slightly different from the one in the documentation pictures.  Possibly a new revision?  Could there be an error in the daughter board?

Or...switches. Maybe I got unlucky and one of the two is mechanically defective.

A
So, I'm going point to point with a meter.

I found one interesting little tidbit when checking continuity, from Buffer out to J. out with the effect bypassed and the slider set to buffer bypass.

I'm getting 68k between those two points.  Huh?  I checked and double checked how I had the switches set, and even checked in all four switch orientations, I consistently get 68k unless I'm in true bypass, bypassed, where I read infinite. Attached a edited drawing to illustrate what I mean...I should see close to 0 ohms in this configuration between these two points.

I'll see if I can dig a little more into the daughter board point to point...try to figure out exactly what's happening here.

R-28 is good 100k, measures out at 100K.  Will look at R-3 and R-4 as well.  Thank you all for the suggestions so far.

[idy]

The schematic is hard to read because there already trick bypass of the Klon now has a true bypass switch. You should see 68k from buffer out to output jack when the effect is engaged, and continuity when bypassed. You should see the opposite when measuring the effect out and there output jack.

Basically, in stock mode, the buffer and effect are always connected by 68k to the output jack. Switching modes then shorts out one of those resistors and, in bypass, grounds the effect signal right after IC1B, where the clipping diodes are. The idea is by never making a complete break in the circuit, less pop when you engage/bypass.

Switches....they are very sensitive to soldering heat and can go bad. but replacing them kind of means tossing the board they are soldered to and starting over. First be absolutely sure you are not getting the open/close circuits you need. Make sure you are not looking at the switch sideways! (or didn't solder it in the board sideways!) Do you know how a switches terminals are numbered? And how they work?

SW1 (A, B, and C) is the toggle slide switch for buffer/true bypass, right?
FS1 is the stomp bypass/engage, right?

Annoyingly, the (full) schematic you posted does not include the full foot switch. It includes the two poles that actually do the bypassing, but does not include the part that selects indicator LED or  "muting" at the clippers. Those two things go together: either the LED is going to ground= LED lights and sound goes to next stage, or the signal is grounded and the LED goes dark. Schematic shows a little "DSW" there, but no switching. 

[Stickman393]

I can read schematics, interpret them, apply them to the real world.  I'm also able to look up data sheets and gather information like pinouts, HFE, blah blah blah.

That said, I'm far more comfortable working with AC and Loads than I am with DC and semiconductors.  Part of working in HVAC: 95% of the stuff I troubleshoot is electrical in nature, but I typically don't have to work with DC unless I'm working on an inverter or a simple controls circuit.

Most of the time it's pretty obvious when a semiconductor fails in my field.  It's hard to get the smoke back in the board.

Back to my refractor...

After double and triple checking my work, I've discovered that the daughter board is missing a trace; I erased the connecting line from the attached schematic.  From Buffer output to pin 6, confirmed both with a meter and under magnification.

Easy enough to put a jumper in there...but...It doesn't explain the problem with the effect ON.  At least not as far as I can tell.

[idy]

I would try jumpering it. Honestly I can't trace how that schematic works. I tried copying it out and tracing bypass and engage for the two configurations don't know. It certainly is missing a few things, perhaps it is f-ed up in other ways.

I would also try looking at someone else's schematic.... but can't find one that has switchable buffer/true bypass.

Others have had success with that pcb... I think....

[duck_arse]

I want to say that it's good to see you care enough to have bent all the resistors so they show the printed value uppermost, but I also want to say "bloody things, they need colour bands" because the most important part of that resistor value, the K, is all that is missing. rubbed off?

and by all means, refractor builders with a problem not answered in an existing thread should start a new one, but it seems many newcomers first build is a klone of some sort, and end up, well, with a thread.



oh, and welcome to the forum, dilettanti.

[Stickman393]

Shoot, AION got me spoiled in regards to resistor identification.  I had been using xicon metal films ever since I first started building, then I see these red things with the value printed directly on em.  Now I'm ordering Vishay Dale RN series by the 100s and PRP PR series TC50'S for all my builds.

Which...overkill, yeah.  I agree.  I'm a hobbyist, not a professional builder.  What, you mean to tell me that those gold electrolytics are better in the "audio path" despite having inferior longevity stats?  Nevermind that I don't know much about how a capacitor operates in a circuit when we're not taking phase shift and power factor into the equation.  I'll just throw my wallet at this money sink, thankyouverymuch.

Only thing about the aion resistors, though, is that the ink seems to be alcohol soluble.  Ah well.

dilettanti, could you check your refractor against my measurements?  With the daughter board unplugged, the effect bypassed and the e-switch set to buffer bypass, could you measure between the output jack and the buffer out pads?

I'm just curious if this could be part of a production issue.  Not that I'm throwing shade at Aion, they got a good operation over there.  Mistakes are bound to happen. 

EDIT: As I've been searching through the previous threads on this subject I'm seeing a lot of boards that look am awful lot like mine.  I'm becoming increasingly skeptical of my hypothesis that this is a PCB related problem.  I suppose the next step is to build an audio probe, re-flow the switch joints.

I've attached my mock up drawings of each of the four switch positions, too.

[dilettanti]

Sorry for disappearing - I realized I had to do a *lot* more work to diagnose my own problem. Turns out I had lifted a pad at R2 (on the C1 side) - almost certainly my own darned fault. I had to jumper between C1 and R2, which is a challenge with such a packed PCB. In doing so, I lifted *another* pad - this time on C1 (on the R1 side - ugh). I didn't want to wire in another jumper, especially with the components so close, so I just created a solder bridge between R1 and C1 - but because of R1's orientation on the PCB, I effectively removed R1 from the circuit. But it works now!

To the extent you're still having problems finding the issue, I cannot recommend an audio probe strongly enough. I built one to connnect an instrument cable into my amp with my multimeter probes - see pics on Reddit. Using this was straightforward - I just plugged my looper output into the pedal's input, clipped the probe's ground connection to the input jack, and touched the signal probe to the various compents in the buffer chain, starting at the very beginning (RPD, R1, C1, etc.). It was clear pretty quickly that my problem was with the trace between C1 and R2. Super easy to put together, super easy to use, and it identified the exact location of the problem for me. I now have a working pedal (just missing R1 from the circuit, but whatever).

Good luck!

[aion]

Here is the omitted part of the switch wiring -


The only difference from a normal 3PDT bypass routine is that the "D.SW" point is grounded in bypass mode where the switch would instead be grounding the circuit input in most other effects. I usually leave the LED pole off of schematics just because it's always the same and it cuts the visual clutter, but yeah, in this case it's very slightly different in execution than most others.

I'm just curious if this could be part of a production issue.

Always tempting to consider when hair is being pulled out by the fistful! But I'm currently sitting at only 3 or 4 confirmed PCB production errors in almost ten years (etching errors, or once a metal shaving that was stuck under the solder mask)... so while it's not impossible, it's extremely unlikely and I wouldn't spend too much time on that branch of the troubleshooting tree.

The voltages do look OK. IC1 pin 3 is entirely dependent on the multimeter used (different types have different loading), so if the "max" function showed 3.73V then I wouldn't worry about where it levels off and stabilizes.

When I have weird problems I always go through and touch up every one of the solder joints (either the whole PCB or in just one area of the schematic if I suspect it's a localized issue). That fixes it more often than you'd think, even if the joints look good visually.

And I would second the audio probe suggestions. You can rule out the switch board if you're not getting signal at the "FX Out" pad on the main board - and vice versa, you can isolate the switch board if you are getting signal at the main PCB out. But beyond that you can figure out pretty easily what part of the circuit is causing it.