HELP w/ TC ELECTRONIC SCF Unit ~ Wiring 'Ex. Bypass' Question

[RJB_SOUND_DESIGN]

Hey PEDAL PCB members,

I'm strugglin' to figure out how to rewire the external bypass jack on my old TC ELECTRONIC SCF unit. It's a standard 3.5 mm (AUX) Cliff mono jack. I'm currently using a custom bypass switch (simple dpst to mono jack) and I'm trying to bypass the unit with the ex. bypass jack. However, it doesn't appear to be working. Here's a couple pictures of it...

Please let me know if you guys have any suggestions / recommendations as to fixin' the unit. I'm hoping to have it fixed before I play at the Whisky A Go-Go in Hollywood in 2 weeks! Thanks, everyone!

- Ryan / RJB Sound

 

[chris.knudson]

Maybe it's me, but I'm not sure I understand what you're asking. I think you're trying to bypass the expression pedal input on a TC Electronics SCF Chorus Flanger Pedal. So my first question is why? And, the second question is what are you trying to achieve -- full on, full off, somewhere in between?

 

[RJB_SOUND_DESIGN]

Hey chris.knudson,

The reason I'm trying to use the external bypass on my TC ELECTRONIC SCF is because I set it on top of my amplifier (mainly because it has an AC power cord ~ I usually keep everything that has an AC power cord close to a multi-plug setup near my amps so I'm not using 10 ft. - 25 ft. power cords to and from my pedal board). The purpose of the external bypass it to completely bypass the effect (on - off, off - on). I hope this helps. Thanks!

- Ryan

 

[chris.knudson]

Hey chris.knudson,

The reason I'm trying to use the external bypass on my TC ELECTRONIC SCF is because I set it on top of my amplifier (mainly because it has an AC power cord ~ I usually keep everything that has an AC power cord close to a multi-plug setup near my amps so I'm not using 10 ft. - 25 ft. power cords to and from my pedal board). The purpose of the external bypass it to completely bypass the effect (on - off, off - on). I hope this helps. Thanks!

- Ryan

Ok, I understand what you're trying to do. Have you taken it out of the enclosure? It should be a simple fix, but without seeing how it connects to the circuit, I don't know where to have you start. Also, have you had it working before with that switch? That pedal takes a momentary switch, so if your dpst switch is a latching switch, I don't think it will work.

 

[chris.knudson]

@RJB_SOUND_DESIGN Any updates? I know you have a gig coming up, and I want to get you up and running in time for the show.

 

[RJB_SOUND_DESIGN]

Hey @chris.knudson,

Sorry for the late reply! It's been a crazy week gettin' everything ready for this upcoming gig. So, I wired the new Cliff jack the same as the original one. The reason I replaced the original 3.5 mm jack (which wasn't the original Cliff jack found on this unit ~ probably replaced by the previous owner for whatever reason) is because it's plastic case was damaged. However, the new jack SOMEWHAT works. Here's a few pictures to show what I'm talkin' about...

I'm using a George L's 3.5 mm mono plug for the external bypass switch. The other end of the cable is a George L's 1/4" mono plug going into a mono jack, which is then connected to a DPST switch. I also replaced the switch with a simple momentary SPST switch, per your suggestion, and have still had no luck. It appears that once the tip of the plug makes contact with the "tip" lug on the jack, it'll turn on - off and off - on. The 3.5 mm plug has continuity when turned on - off via the DPST / SPST switch. Maybe it's my switch mechanism? Let me know what you think. Thanks again!

- Ryan

 

[chris.knudson]

Hey @chris.knudson,

Sorry for the late reply! It's been a crazy week gettin' everything ready for this upcoming gig. So, I wired the new Cliff jack the same as the original one. The reason I replaced the original 3.5 mm jack (which wasn't the original Cliff jack found on this unit ~ probably replaced by the previous owner for whatever reason) is because it's plastic case was damaged. However, the new jack SOMEWHAT works. Here's a few pictures to show what I'm talkin' about...

I'm using a George L's 3.5 mm mono plug for the external bypass switch. The other end of the cable is a George L's 1/4" mono plug going into a mono jack, which is then connected to a DPST switch. I also replaced the switch with a simple momentary SPST switch, per your suggestion, and have still had no luck. It appears that once the tip of the plug makes contact with the "tip" lug on the jack, it'll turn on - off and off - on. The 3.5 mm plug has continuity when turned on - off via the DPST / SPST switch. Maybe it's my switch mechanism? Let me know what you think. Thanks again!

- RyanView attachment 63476View attachment 63477View attachment 63478

Yeah, I think it might be your switch. You just need a momentary switch to trigger the bypass. In other words i't only on briefly while you push it.

 

[RJB_SOUND_DESIGN]

Hey @chris.knudson,

Still no luck with a momentary switch. The ONLY thing that turns the unit on - off is removing and re-inserting the 3.5 mm plug into the ex. bypass jack.

- Ryan

 

[chris.knudson]

All I've been able to find is this... https://toneprints.com/media/218428/tc_electronic_scf_stereo_chorus_flanger_manual_english.pdf
I don't know that much about the momentary switch that this pedal uses, but there are normally open and normally closed switches. The only guess I'd have is to try a normally closed momentary switch. If you have an 1/8" cable that you can sacrifice, you could try just shorting the leads in both an on and off position to see if you could get the pedal to do anything. The fact that it turns on and off makes when you reinsert the cable makes me suspect the switch, but so far I have nothing.

 

[Feral Feline]

How'd the gig go?

Any further progress on this switchery? (I know, it's unlikely given the busy holiday season).



Always wanted one of these OG units, never found one before Internet sent prices through the roof.
That's why I'm hoping @Robert gets a PCB sorted.