Help for noob switch-mod of guitareffect

[hvedemelsbof]

Hi Electro-tech. I'm in need of a little help building my new guitar-effect rack!

Basically what i wan't is that my effects must be switched on automatically, when power is present, since i'm going to wrap it all up in an aluminium box and put the potmeters of the pedals on the outside. I won't be able to reach the pedal switch. One of the effects is build to switch on automatically, when powered - the other one is not.

I found some schematics and PCB layouts of the 'bad' pedal, with the switch being the most important:
**broken link removed**

The switch is basically just making contact, but it won't work to just constantly pressing it, while turning on power - it seems like it has to 'feel' that the switch is off before it works (i'm thinking it might be something about the capacitor close to the switch?).

So what do i do to get the effect switched on when turning on power? It doesn't matter if i can't switch it off, since i'm going to have it in a true bypass loop anyways.

The schematics
The PCB
**broken link removed**

Have in mind that i'm very noob in electronics - i know how to solder and read a multimeter - that's about it

I'm not english if you haven't figured it out yet So sorry for bad spelling.
Thanks in advance!

Hvedemelsbof
(Denmark)

 

[Blueteeth]

Tube screamer fan eh?

Well, do you wish to modify the medal so that it will ALWAYS be on, or just so it's default state is 'on' when its powered up? The first option would mean that, if you use it 'outside' of your rack, you'll never be able to bypass it.

Good call on the schem and PCB though, makes it far easier to see 'how to mod'.

Like almost all active bypass pedals, the audio is routed through JFET's, controlled by a two-transistor monostable multivibrator. Latch on, latch off style.

The simplest way I can think off is to swap the wires connecting to D13 and D14. You can either do this on the 'function switch PCB' at the bottom left of the schem, or on the 'output PCB'. I'm assuming these two PCB's are connected via a two-pin plug (P410 on the schem), so simply swap these connections.

Why? Well when one JFET is on, your 'clean' single is sent to the output (in bypass), when the other is on, your 'dirty' signal is sent. When you first power the pedal, the multivibrator defaults at a state when the bypass JFET is on and the other is off. Swapping the connections between these means the default is 'on'.

I'm pretty sure that'll do it, plus, no modifications to the actual PCB's required, just the connector, so its completely reversible

Blueteeth

Ps. Your English is better than mine.