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DIY Stompboxes => Building your own stompbox => Topic started by: JPGraphX on September 12, 2013, 02:08:22 PM

Title: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 02:08:22 PM
Hi,

I have built a Chimaera BFD. I'm trying to debug it. I got sound when pedal is off and I also have sound when pedal is on. But I don't have a lot of gain, and it seems to be reversed. More gain at 0. I double checked my dual gang, and it's perfectly wired..

Any idea?
Thanks
JP
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 02:09:30 PM
(http://img.tapatalk.com/d/13/09/13/uda4utyp.jpg)
(http://img.tapatalk.com/d/13/09/13/ara6yta2.jpg)

I have to clean my PCB..
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 02:22:19 PM
I replaced 1N34a GE by 1N914 until I received my 1n34a
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 02:34:30 PM
Okay Here is an update, I cleaned my PCB and didnt change anything. What I've found is that my amp was too Low volume. (Im testing on my small crap amp). At high volume I got a lot of Overdrive. But my dual gang pot is still reversed lol
Title: Re: Chimaera debugging
Post by: SmoothAction on September 12, 2013, 02:44:40 PM
I noticed my builds becoming better (and working straight off the bat) when I started to really take my sweet, sweet time on them. In nature I'm not a patient person, and it reflected in my earlier work. I spent more time debugging (a great learning experience in itself) than actual building of said pedal. I figured if I slow waaay down and get in a "zen" mode I would have more success. I absolutely did.

We all want a working pedal. I'm a "I want it NOW" kinda guy, but putting the effort in before you fire it up is crucial. The only advice I can give you is to go through the debugging page, like always, and be patient AND precise when building. It does look like your solder points look a bit dull, may just be the photo though.
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 02:48:27 PM
I think I have improved a lot my solder in the Last month. But as I said, pedal is working great but potentiometer is working reverse..

Here is a picture of my cleaned PCB.

(http://img.tapatalk.com/d/13/09/13/ge9e3yvu.jpg)
Title: Re: Chimaera debugging
Post by: SmoothAction on September 12, 2013, 03:00:28 PM
Recheck pins 1 and 3 on your gain pot in relation to the pcb terminals. Sounds like they are reversed
Title: Re: Chimaera debugging
Post by: SmoothAction on September 12, 2013, 03:01:19 PM
Yea the board looks great now! Nice n clean.
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 03:01:44 PM
On my PCB they are wired, 3,2,1. Same on pot, 3,2,1 (back view)
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 03:02:45 PM
Thanks! That's my best build. But pcb was reverse gain at left and volume at right and I wanted it to be like the original so it looks not very great (wire)
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 03:20:59 PM
When my potentiometer is wired, can I test it with multimeter? I read 0 to 100 on the Gain1 and 0 to 20 then 20 to 0 on the gain 2
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 03:22:51 PM
Is this normal because I'm wired or it mean my potentiometer has over heated? Because it was good before I install it (I tested it!)
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 06:06:25 PM
I dont get a lot of Overdrive..
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 06:31:23 PM
Okay Here Last update: I reversed lug so my potentiometer is now working Ok and By the way I changed my pot..

Final result ; it is working but Im not getting as Overdrive as I should, I'm pretty sure (I get a lot more from my maxxon)
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 12, 2013, 06:40:50 PM
I measured IC voltage and they are very close to someone else results.. So anyone got an idea?

Please!
Title: Re: Chimaera debugging
Post by: midwayfair on September 12, 2013, 11:29:27 PM
When you say you "aren't getting a lot of overdrive" are you saying that you
a) Don't have much DISTORTION when the gain knob is turned all the way up?
b) The gain knob does not increase the OUTPUT when you turn it up?

If it's a, it's probably because you used silicon diodes. It's going to be cleaner because your clipping threshold is higher.
If it's b, there's something else wrong. The gain pot should boost a lot.

Also, this is not a "high gain" pedal. There isn't a ton of distortion even when using the correct diodes. It's made to push an amp into its own overdrive. The added distortion in the gain control is just icing.

Also, although you can't post the schematic here, it would still be polite to post a link to the build document so people can see the layout you're working from.

You'd also probably get more responses if you posted your voltages.

Finally, you boxed up your circuit before testing it. This just adds more factors to the equation - the switch, the box itself, the wiring ... it's always a good idea to test a PCB on a test rig before you put it in the box. It doesn't have to be fancy. You can make a test rig for less than the cost of that PCB with a breadboard and some jacks.

Finally, saying that something "doesn't work" but that you're sure you've wired it correctly is ... a little illogical. If it was wired correctly, it would work correctly, right? It's possible that there's a mistake on the silkscreen. You have to go by schematics as a backup. The pictures you posted don't allow us a clear, unobstructed view of the wiring, which makes it impossible for us to verify that you did it correctly.
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 13, 2013, 03:46:07 AM
Thanks for you great info and tips. I know this is not a high gain pedal, but I was expecting more distortion with the knob all way up with the many sample I've heard. I have used almost all the exact same component..

My diode can change a lot my distortion?

For my build info: http://www.grindcustomsfx.com/forum/viewtopic.php?f=2&t=180 (http://www.grindcustomsfx.com/forum/viewtopic.php?f=2&t=180)

And for my voltage at IC:

           IC1          IC2              IC3
1    +4.63V    +4.6V        +9.24V
2    +4.64V    +4.63V      +4.62V
3    +3.55V    +4.63V      0V
4    0V             -9.24V         -4.63V
5    +4.63V    +4.63V      -9.22V
6    +4.63V    +4.63V      +3.97V
7    +4.61V    +4.66V      +5.29V
8    +9.27V    +17.02V    +9.25V

I don't have my build with me right now, but these voltage are very very close to what I get when I measured them.

Thanks!
JP
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 13, 2013, 03:56:50 AM
I said it was wired correctly because I followed the pcb, but there is an error on it for the gain pot wire order. So it was reversed. But I'm a mechanical engineer, so I'm doing my very best to learn and improve at electronics but I'm still not good enough to follow schematics..!
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 13, 2013, 03:14:32 PM
I've found 1n34a, I will test them now to see if it is my issue
Title: Re: Re: Chimaera debugging
Post by: JPGraphX on September 13, 2013, 04:58:48 PM
Yeah Sorry http://www.grindcustomsfx.com/forum/viewtopic.php?f=2&t=180