FA-1 clone pedal, i need help...

[heathfball20]

Ive built an FA-1 clone using the Prism circuit board from aionelectronics.com .

Here is my issue, when the pedal is put together, it powers up and has sound however, the sound is distorted. Bypass works as it should.

I accidentally ordered pots that have detents. Didnt know until i had installed them. But it seems that the pots are the issue. They crackle and buzz when i touch them which sounds like a grounding issue, but im not sure if that explains the terrible sound.

I have checked for solder bridges by going inbetween with a razor. Reflowed weak looking solder joints, rewired, everything looks correct. Im stuck on the pots though.

Sorry so short. Let me know if you need more info for diagnosis.

[PRR]

> pots... They crackle and buzz when i touch them

The pot shafts should be in a grounded metal enclosure, so should not crackle.

The pot terminals are usually very sensitive circuit points, and *will* amplify all the crackle and buzz on your body. So don't touch them when using the pedal.

[heathfball20]

When the knobs are on and they are tight to the enclosure, the pots cut the sound in and out when i turn them. And the sound is super distorted. I know it naturally has a lot of gain, but its supposed to be a boost. The pre amp volume on my amp is pretty low so i can get a nice clean sound.

[heathfball20]

I ordered new pots that are smooth turn rather than detented. 1 because i prefer smooth pots and 2 i hope to eliminate the possibility that it is the pots. I have no doubt that the PCB is done 100% to the build sheet Kevin provides through his site.

To be more specific, i turn the trebel pot, the sound cuts in and out, same with the volume pot. Not so much with the bass pot.

[aion]

The pots are insulated against the PCB, right? I usually use the pot covers from Small Bear, but you can even just use a piece of cardboard.

Next step would be to post a photo, and then the voltages on each of the pins of the op-amps.

We'll get it going! It's a great circuit, definitely worth the time to debug!

[heathfball20]

Yes, the pots are insulated from the pcb using those very same covers from small bear. I will get a pic posted. ASAP. I used the HW1457 ICs rather than the 8 lug op amp IC. So I need the voltages from each pin on both ICs?

[heathfball20]

http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/image_009.jpg.html?g2_imageViewsIndex=1

[heathfball20]

Voltages I wrote down.
http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/image_010.jpg.html?g2_imageViewsIndex=1

[heathfball20]

The first URL is the pic of the PCB
The second is the voltages of the ICs I drew up and the transistor. The flat side of the transistor on the right of the circles

[heathfball20]

I guess this helps better, now that ive read the  debug page.
Q1
C=8.71
B=0.68
E=4.40

IC1
P1=4.08
P2
P3=4.10
P4=0.00
P5=0.63
P6=4.28
P7=4.33
P8=8.71

IC2
P1=2.81
P2
P3=3.31
P4=0.00
P5=0.26
P6=4.28
P7=3.80
P8=8.72

D1=8.71
.

[heathfball20]

Schematic
http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/FA-1+schematic.jpeg.html?g2_imageViewsIndex=1

[idy]

The transistor should be an FET, which pinout is SGD, not EBC. The type of FET is probably not critical as it is a buffer, but the pinout should match (or be bent to match) the layout.
The voltages on the ICs look about right, 0 on pin 4, close to 9 on pin 8, and half voltage on pin 6.
I can't see C14, but C13 is missing. The Opamps should have these two caps.

It's a neat build. Hope you don't have to remove the pots.

I've built a few of these, I think at least one on a "prism" board, but only used the old-fashioned single op-amps in single line packages on one that i don't have here so I can't compare voltages.

[heathfball20]

Ahhhh!!!! I went back and read on C13 & C14. I totally got it backwards. I misread that big time!  They are supposed to be left empty if i used a 4558 style op amp. Lol, thank you for bringing that to my attention. Lets see if 2 100pf caps will do the job.

[heathfball20]

Idk how i missed that studying the schematic as long as i did. Lol. Staring me right in the face and i didnt pay attention.

[heathfball20]

The transistor is Fet. SDG. The EBC is from my copy and paste from the debug page. I didnt think to change that.

So i just soldered in the 100pf caps in C13 & C14 and IT WORKS!!!! Thanks to my negligence and your genious, together we made this work!

I really appreciate it. It sounds sooooo good!

[idy]

Some days you eat the bear, some days the bar eats you. It's always easier to see someone else's mistakes.

That's a pretty useful pedal to have. I ended up using it for a vocal mic, just to get rid of the boominess on a headset, brighten up my breathy voice.

I tried briefly to add clipping diodes and turn it into an OD, but didn't play enough to make this work. I also think of experimenting with the freqs of the B and T, or adding a midrange.

[aion]

Awesome - glad you got it working!