Aion Comet (BOSS DS-1 Clone) [FIXED]

[mattc]

Hi all -

I hope it's OK to ask for help on an Aion project here.

I'm building the Aion Comet (BOSS DS-1 Clone)
https://aionelectronics.com/project/comet-boss-ds1-distortion/

The problem is that I'm getting no output at all. 

I used the cap values from the vintage side of the parts list as well as "Mod 1" and "Mod 2", the resistor values all come from the vintage side of the parts list, and used a TL072 for the chip.  I had to combine two resistors in series to get 22R for R7.  I measured them with my DMM outside the pcb and get 22.2R.

What I've done so far:

• I've reflowed all my solder joints.
• I've used an audio probe. 
  
  
  
  • I get signal for R1-R6.
  • R7's signal is really fuzzy
  • I get signal to R8
  • I don't get signal to R9-R12 (I didn't measure R13 on, I can if needed).
  • I get signal for C1-C4.
  • I get no signal at C5.

Using a 9.12v OneSpot, the voltages to the TL072 are

• 1.437
• 1.414
• 1.431
• 0.6
• 1.084
• 1.431
• 1.432
• 9.12

Q1:

• 3.67
• 4.05
• 9.12

Q2:

• 11.9
• 0.599
• 3.89

Q3:

• 3.38
• 3.61
• 9.12

Pictures:

[somnif]

It appears you messed up a bit with the LEDs in the bottom diode section. According to the build doc the middle 2 pads are connected in each section, so you should have soldered them in the outer pads. (for example: https://aionelectronics.com/wp-content/uploads/2016/08/COMET-1-800x600.jpg )

(I don't have a board on hand to verify that, just what I read in the build doc)

May not be the source of your problems, but it is something to be aware of as it will basically leave the circuit without clipping in that mode (no idea what a DS-1 sounds like sans clipping)

[somnif]

Additionally, the "vintage" spec omits R11, and you have something in place there (again, no idea what including it would do). never mind, misread the BOM here, R11 is the vintage proper one.

I'm wondering if going the "vintage" spec but then using the "modern" chip is a cause of your problems?

Looking at the PCB it appears (maybe?) that without R23 and R24 the chip isn't actually connected to the rest of the circuit properly, though I only have a top image of the board so I'm not sure what is going on with the bottom. https://aionelectronics.com/wp-content/uploads/2014/09/ds1_pcb.jpg

I'm sorry I can't say with more certainty as I've not built this beast. Hopefully someone else with a better eye chimes in.

[mattc]

Thanks somnif.  I've gotta run some errands with the kids, but when I'm back, I'll try putting in those two resistors.

[mattc]

I'm wondering if going the "vintage" spec but then using the "modern" chip is a cause of your problems?

Indeed that was the problem.  I misunderstood the build doc.   I thought I could pick and choose between vintage and modern, but that's not the case.  If you use the modern chip, you use all the values from the modern side of the build doc.

Now that I've done that, it's fired right up.  I went ahead and did all the mods as well, and it's a fun little distortion box.  Of course, now I want to find the vintage chip and build one to complete vintage specs.

Thanks for all the help!