Guyatone - WR-2 Wah Rocker

square wave · Post by **square wave** » 27 Jun 2013, 12:55

SW2 completes the dry blend path running from U1B.7 -> C7 -> SW2 -> C18, connecting to the wet path just after R26. The Q2 short doesn't connect to the dry path, it connects between R26 and R6.

LooseCannon · Post by **LooseCannon** » 27 Jun 2013, 13:23

Ohh sorry my mistake, the blue line threw me off so I thought Q2 with the "i" connection of SW2.

LooseCannon · Post by **LooseCannon** » 27 Jun 2013, 13:24

BTW, what NPN could be used for Q3?

square wave · Post by **square wave** » 27 Jun 2013, 13:55

Without opening a Wah Rocker and seeing what they use, I couldn't tell ya. What I would do is try several different standard types (2N5089, MPSA18, etc) and see if they have any significant effect on the sound.

LooseCannon · Post by **LooseCannon** » 27 Jun 2013, 16:09

Will do, thanks!

atreidesheir · Post by **atreidesheir** » 28 Jun 2013, 00:29

be very careful. I opened one of these up for repair 5 yrs ago and the the wiring inside is incredibly flimsy. I replaced all of it. because most of it broke just from opening the enclosure. and this warning is from an owner of these micro pedals and loves them. The rubber flange is pretty sturdy and no big deal, but the wires used in these is really really flimsy.

LooseCannon · Post by **LooseCannon** » 28 Jun 2013, 06:58

Thanks for the warning, i'm gonna build one from scratch, not modify an original. But it's good to know for anyone else who might wanna modify one.

LooseCannon · Post by **LooseCannon** » 28 Jun 2013, 18:51

ok i have another unknown: the diode going to the 9DC, any idea what should go there?

square wave · Post by **square wave** » 28 Jun 2013, 18:58

The symbol indicates it's nothing special (i.e. not a schottky or zener) so I assume it's just a standard polarity protection diode. Try a 1N4004 or something similar.

LooseCannon · Post by **LooseCannon** » 29 Jun 2013, 04:47

Thanks for all of your help square wave.

I've almost finished breadboarding it, i'm not sure about R28 going from the second terminal of one of the potentiometers to ground, does "blank" mean there's no resistor there? Then why put a resistor in the schematic there in the first place? Maybe there was one there in a previous version and then removed?

So if it's going directly to ground without a resistor it means that C11 going to the second terminal of VR1 can connect directly to ground as well, correct?

Thanks again.

square wave · Post by **square wave** » 30 Jun 2013, 06:58

I'm guessing the "blank" R28 is actually an omit; that is, they weren't sure if they would need a resistor there before they sent the PCB off to be fabbed, so they created a spot for one, just in case. It's common practice in PCB development.

looselectron · Post by **looselectron** » 22 Feb 2014, 09:09

Greetings from Japan! I've enjoyed the WR2 for years, and wanted to see if there was any difference between the original WR2 and the somewhat rare Stevie Salas SWR-2. I thought I was lucky to get an SWR-2 for only $30...until I powered up, no and sound came out!!!

Comparing the two, all the components values are the same on the main board, but the daughter board (EK 356-2) with the control pots is slightly different. The WR2 has an additional 10k resistor from the wiper of the DECAY pot to the inner lug (closest to the other pot) of the THRESHOLD, in addition to a 1k from the outermost lug (R27?).

: WR2 pot board; WR2 pot board.jpg (47.14 KiB) Viewed 1503 times

The SWR-2 just has a single 1k resistor on the back of the board connected to the lug of the 1M Decay pot.

: WR2 pot board; WR2 pot board.jpg (47.14 KiB) Viewed 1503 times

I'd like to do a sonic comparison but still haven't gotten it working yet, so any suggestions for tracking down the problem and getting it working again would be much appreciated!

AAntonio · Post by **AAntonio** » 06 Mar 2014, 11:17

the layout version, does it work?

Guyatone - WR-2 Wah Rocker [schematic]