Mxr Distortion + [Practice layout not working]

[rockaffe]

Hi all, I know that there are many layouts of this pedal, but I'm starting to learn to create my own and, after some successful attempts with simple schemes (rangemaster, fuzz face, lpb1) I've moved on to something slightly more elaborate. And of course, it doesn't work
I used this diagram as a reference:

https://barbarach.com/wp-content/uploads/2022/01/MXRDistPlus_LM741_Schematic.png

This is the layout I came up with:



And this is the vero:



Not having an LM741 available, I used a TL061 (pin to pin equivalent)

Pin 1: 0.02   
Pin 2: 4.35
Pin 3: 4.66
Pin 4: 0.00
Pin 5: 0.01
Pin 6: 8.70
Pin 7: 9.30
Pin 8: 0.00

I hope someone can help me sort it out.
Thank you!

[antonis]

F - 10 cut (under 10k resistor) "isolates" IC1 out..!!
(no connection with 1μF series cap, hence dead quiet..)



P.S.
Your circuit needs some refinements, like R6/R7 lower values, C1/R1 repositioning, etc..
(but firstly let it work and then we'll see..)

[rockaffe]

F - 10 cut (under 10k resistor) "isolates" IC1 out..!!
(no connection with 1μF series cap, hence dead quiet..)



P.S.
Your circuit needs some refinements, like R6/R7 lower values, C1/R1 repositioning, etc..
(but firstly let it work and then we'll see..)

Thanks for your answer, unfortunately even with your advice it still don't work...

[antonis]

What's the voltage on pin 6 now..??

[rockaffe]

What's the voltage on pin 6 now..??

0.71

By the way I had made that cut after trying the layout without it, then for some dark mystery I thought that was the problem and I made the cut

[antonis]

What's the voltage on pin 6 now..??

0.71

Could we see the solder side of your board..??

P.S.
I presume you took pin 6 measurement with IC in socket and ciruit powered on..

[antonis]

For your convenience ..



P.S.
What exactly do you mean by "it doesn't work"..??

[rockaffe]

What exactly do you mean by "it doesn't work"..??

I mean that I have a small signal on the output.
However, you probably nailed the problem: there were some bad welds and cleaning them from an output of 0 gave a small signal.
Tomorrow I'll try to rebuild it from scratch and see what happens.
Anyway, is the layout done correctly given the schematic I linked?

Thank you so much for your time!

[antonis]

Anyway, is the layout done correctly given the schematic I linked?

Apart from that unnecessary F-10 cut, I presume it's fine..

P.S.
A "small"(*) signal might indicate Distortion pot not grounded..
(IC1 working as a unity gain buffer..)

(*) smaller than about 1.2 Vp-p with Volume pot FCW..

[duck_arse]

disappearing posts?

I see two things. your built board has the IC socket upside down. doesn't matter as it isn't polarised, until you next re/insert the IC - trouble. and the layout shows a 47nF cap whereas your build has 4n7 fitted in the gain leg. this will crimp your style somewhat. reduce the vibes and all.



and seeing as you are at the learning stage of layouting, now is the time to start doing it proper. don't be stretching parts, drop them in at their natural pitch. the 1uF cap should sit on 2 or 3 holes, not 10. same for resistors - 1/4W should be over 5 holes, 6 if you must, but never 10. 4 holes is right out, and will get knuckles rapped.

[Axldeziak]

don't be stretching parts
4 holes is right out, and will get knuckles rapped.

If it works, it works.
And a resistor is fine at 4...
Rap my knuckles and I'd do it on purpose, with 10 smaller mixed value standing resistors chained together, (carbon and metal living in sin together) jumper wired with a coat hanger wrapped around the pedal 6 times. Long ways. And soldered with plumbing solder and a zippo lighter.

[ElectricDruid]

If it works, it works.

...and if it's ugly, it's ugly!

There's a role for *something* here beyond merely functional. The best schematics/circuits/layouts have a certain elegance and simplicity about them, like nothing needs to be added, and nothing could be taken away.

[rockaffe]

Anyway, is the layout done correctly given the schematic I linked?

Apart from that unnecessary F-10 cut, I presume it's fine..

P.S.
A "small"(*) signal might indicate Distortion pot not grounded..
(IC1 working as a unity gain buffer..)

(*) smaller than about 1.2 Vp-p with Volume pot FCW..

So, I waited for some lm741s to arrive and reassembled the circuit. Now it works, even if the output volume is quite low (when activated the amp volume drastically decrease). Could it depend on the fact that the original schematic has a 10k potentiometer while the schematic I followed uses a 50k one?

[duck_arse]

...... the layout shows a 47nF cap whereas your build has 4n7 fitted in the gain leg. this will crimp your style somewhat. reduce the vibes and all.

have you attended to this yet?

the 50k pot will less-load the circuit output, and would increase the output level available, if anything. but the clipping diodes do just that, clip the output to "a" maximum level. if that level isn't enough for your purpoises, you could add a boosting stage, like last Q from a big muff or superfuzz or lpb1 etc. or clip with leds instead. [this is one of the whys we always ask for the circuit diagram - we can then point and say -- look.]

[rockaffe]

...... the layout shows a 47nF cap whereas your build has 4n7 fitted in the gain leg. this will crimp your style somewhat. reduce the vibes and all.

have you attended to this yet?

the 50k pot will less-load the circuit output, and would increase the output level available, if anything. but the clipping diodes do just that, clip the output to "a" maximum level. if that level isn't enough for your purpoises, you could add a boosting stage, like last Q from a big muff or superfuzz or lpb1 etc. or clip with leds instead. [this is one of the whys we always ask for the circuit diagram - we can then point and say -- look.]

I'm almost ashamed to say it, it wasn't the pedal's fault, it was the faulty amp input. Everything works perfectly. Thanks to whoever helped me

[duck_arse]

...... the layout shows a 47nF cap whereas your build has 4n7 fitted in the gain leg. this will crimp your style somewhat. reduce the vibes and all.

have you attended to this yet?

have you attended to this yet?

[rockaffe]

...... the layout shows a 47nF cap whereas your build has 4n7 fitted in the gain leg. this will crimp your style somewhat. reduce the vibes and all.

have you attended to this yet?

have you attended to this yet?

Yes, i did.