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Snack Snack help urgently needed! Now with PCB pics

Started by EndlessOcean, June 02, 2011, 04:18:44 PM

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EndlessOcean

Hey guys,

I need your help with my snack shack. It works, just nowhere near like it should. It's shrill, icepicky, and does nothing more than increase the volume, give a little bit of breakup and give me insane amounts of treble regardless of the setting. It's mildly overdriven but it's such a horrible sound... so crazily bright and in no way shape or form anything like the Meathead it's designed to imitate.

I didn't build this pedal, someone very generously built it for me, but it's like a very very harsh treble boost and zero fuzz... imagine hearing your guitar played through a tiny 1950s radio where everything sounds like it's coming through a tin can. it's like that.

OH, forgot to mention the fact that I'm picking up radio stations with the knob past 3 o'clock.

Here is the pcb:



Everything is stock with the schematic except Q2 (which says SK3020) which I was told is around hfe 400-500 as I was looking for something with ridiculous amounts of gain/fuzz for use in a collaboration with a techno DJ, which is due to be coming up soon!

The wiring is very well done, it's all soldered neatly and perfectly so there's not a problem with cold solder or anything, as you can see here:



So, what's up here? What can I change to make it sound like an actual DAM Meathead? I checked the schematic/diagram on the madbean pdf and it looks good, except that C1 and C5 (the red ones at the right of the PCB) look like they should be going into the holes at the top of the board and not the ones beneath them, which look like they should be left empty according to this:

http://www.madbeanpedals.com/projects/SnackShack/docs/SnackShack_ver1.pdf

so any ideas guys? I'm really looking to turn this into a meaty beast, as right now it's unusable.

In case you're wondering, I'm using a Les Paul into a custom designed amp (Soldano lead 50 crossed with a Mesa Mk II) so it isn't the guitar, amp, or leads.

EDIT: just checked the datasheet for the RCA Sk3020 (the tranny in Q2), apparently the hfe is 125... could that be responsible for the lack of gain and tinny/buzzy sound?

Edit 2:

I didn't include any shots of the business side of the PCB before since I didn't have any, but now I do. Upon closer inspection (and better lighting) I can see they're are a few solder bridges and also one or two cold solder joints, but I'm not sure if this is an issue.



this might be a better angle of everything:








EndlessOcean


sprayfe

check your transistor pinout on both of those badboys. I've built several of these, they're pretty rockin.


EndlessOcean

I have, it's all good. Q2 has the twisted legs.

I'm gonna make an order for some other trannies, and socket them up to see if it really is Q1/Q2.... if that doesn't solve it, I'm out of ideas.

cjkbug

I'd reflow the solder joints while your at it. more than a couple look suspect. a few looked pretty scorched. he might have cooked a transistor.
I got blisters on my fingers!!!

EndlessOcean

reflow?

Do you mean desolder, and then resolder?

Apologies for asking, but I'm not familiar with the vernacular :(

bigmufffuzzwizz

Quote from: cjkbug on June 03, 2011, 04:32:02 PM
I'd reflow the solder joints while your at it. more than a couple look suspect. a few looked pretty scorched. he might have cooked a transistor.

I agree that some of those joints on the back really don't look good. To reflow the solder joint just heat it up and try to get it to set shiny and hersey shaped. Adding a little bit of new solder helps too because of the flux in it.
Owner and operator of Magic Pedals

bigmufffuzzwizz

These are the ones I would focus on reflowing the most..Do you have an audio probe?

[attachment deleted by admin]
Owner and operator of Magic Pedals

EndlessOcean

No I don't, all I have is a soldering iron and some good intentions.