Problem with Aion Comet (BOSS DS-1 Clone)

[matt_crooks]

Hi all -

I'm trying to build 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:

[PRR]

Welcome.

An excellent trouble description. But looking at the build documentation, I am totally puzzled how the dual-opamp version works. The schematic shows a dual-opamp fragment but not how it replaces the single opamp.

Maybe someone else here knows?

[aion]

Yes, the Comet schematic doesn't actually show the connections for the dual version, but if you look at the factory DS-1 schematics for the old and new versions you can see how it's done (mine is the same & supports both versions). Don't have links at the moment but I can dig them up later.

Sorry that's not as clear as it could be - I didn't want to visually connect them on the schematic because I was worried that people would see them as being part of the same circuit when it's just one or the other.

[caspercody]

You used the vintage values, but are using a TL072 for the modern sound.

I made one of these using TonePads layout, and I made it using the vintage IC (TA3176). But there are differences with the components when using one or the other. I do not think you can use the vintage components with the modern IC?

http://www.tonepad.com/getFile.asp?id=78  (for reference to components list for both IC's)

[EBK]

First pic, left side, middle.  What is that bit that looks like a tree knocked over in a storm? (Looks like a resistor is uprooted, taking the pad with it....). I'm guessing it is just a series combination of resistors upon closer inspection. 

[aion]

If using the dual op-amp, make sure to include D6, R23, and R24 and omit R11 and C6. (essentially using the "modern" values for the section immediately around the op-amp)

However, I'd recommend not mixing vintage and modern, instead do all one or all the other. The vintage values are tuned for the SIL op-amp circuit while the modern values are tuned for the dual op-amp circuit. The modern circuit with the modifications is very good, but the EQ may not be right if some of the values are taken from the vintage version.

[matt_crooks]

Thanks, that's what I did... including all the mods, and now it's up and running!

Now I want to track down the original chip and build one to vintage specs.