Beginner Needs Help: "Micro" Switch Swap?

[rbarone]

Hello All & Thanks for any & all support.  If possible, I'd like to replace the existing micro switch on a pedal with a standard stomp box switch.  I don't know if it's possible, or if it is, how to wire it up correctly.  The micro switch has 4 contact points & is soldered directly to the board.  Would like to post up some pics to illustrate, but don't know how...  thank you

[GibsonGM]

Hi Rbarone, and welcome!  Yes, it's POSSIBLE, but you also have to think about how much real estate you have to work with (space for the new switch).  They are pretty bulky compared to micros!!

Yes, pics are certainly in order.   Upload them to your favorite site like Imgur or photobucket....come here, make a post, click the "picture icon" on the post toolbar.   You'll see "{img}{/img}" come up in braces.    Place the URL to your pic in between the brackets...the code just means "start image" and "end image".        Click "Preview" and you can see if it worked before posting.

We'll look for your post and tell ya what we think!   Many have done this, like I said, real estate...be sure to show the enclosure etc. to see how much space is in there...give the full name of the effect so we can find a schematic, too, please.

[rbarone]

Thanks Gibson.

Here are the pics.  As you see, it's a behringer pedal...  the "tube modeler".  I own 3 different Sansamps, & this thing is shockingly similar in performance, albeit, a cheaply built knock-off. 

Real estate isn't an issue..  I'll put in an enclosure to suit.

[duck_arse]

rbarone - looks like you've got the pic posting mastered right kwik.

if you head over to geofex, and search up "the technology of JFET switching in boss and ibanez pedals", it will explain the workings and the moddings of your bypass. it was nice of behringer to add the component values to the board, innit?

and welcome.

[rbarone]

Thanks Duck -  good & thorough article, though some of it was over my head...  I guess what I really need to know then - what type of replacement switch (SPST etc etc) & which lugs get wired to which spots on the board.

[GibsonGM]

As you can see, not too difficult at all, just that the new switch will be a LITTLE bit bigger, ha ha...

[slacker]

If you look at your first picture you'll see that the top two legs of the switch are both connected to the big filled copper area and the bottom two legs are connected together by the thin trace running between them, so there's really only two connection points not four, so it's being used as a SPST. You probably want a normally open "NO" momentary SPST switch but without testing it or seeing a schematic I can't say for sure. Do you have a meter that you could test the switch with to find out for sure?

[rbarone]

Slacker - I see...  yes, thanks.  I do have a meter.  I apologize for not knowing how to perform such a test.  Can you please advise?

[GibsonGM]

You can use the ohmmeter or continuity function...continuity is easier (the "beeper" setting).   

If the switch is not broken, just connect your meter to 2 legs opposite each other - it should do nothing.  When you press the switch closed, you should get a beep from the meter (or, you will see the ohmmeter setting 'engage' from a non-moving meaningless display to some VERY low value of resistance that will probably settle to zero).     

This is a continuity test.  No continuity w/switch open ('not pressed'), and continuity if it is pressed (closed).   99% likely that is a normally open switch...it connects 2 separate 'pathways' (circuit traces) as Slacker described.

[rbarone]

Thanks!  Well, I'm getting a beep from both opposite pairs, with the switch engaged & disengaged.  Does that make any sense?

[GibsonGM]

Same same, no change?   Only if the switch is broken, and locked in a closed position.   Or if it somehow works of of 'diagonal' tabs, LOL...not too likely IMO.   
Or do you mean one set acts in the opposite way from the other?



While you have it open like that - can you heat & suck all the solder off that switch contact area?  It's hard to see what's going on, and I can't find a schematic online...

[smallbearelec]

Hi--

You need to figure out which two points on the board are connected by the switch. Those small tactile switches are almost always normally open, in which case the stomper you want is this:

http://smallbear-electronics.mybigcommerce.com/momentary-spst-no-soft-touch/

Solder wires to the points on the board and try touching them together quickly. If you get switching action, you are good to go with the stomper.

[Jdansti]

Be very careful to avoid damaging the pads where the traces are when you desolder the existing switch.  I don't know what your soldering skills are, but I'll assume you're new at this. If it were me, I'd use a solder sucker tool and/or copper braid and remove as much solder from the four pads as possible. Then I'd try to remove the switch. If you're having trouble getting all of the legs free and pulling the switch off, you might be able to cut the legs off of the switch with some small cutters (this would be on the top side of the board where the body of the switch is) and desolder each leg separately.

Here's a good video showing the copper braid and sucker tool methods.

[rbarone]

Many, many thanks...  I'll pick up some copper braid before I have a go at it then.

[GibsonGM]

Yes, as John pointed out, be careful man.  Don't want to overheat the traces on the board. If you are committed to doing your swap, gently remove the switch (or cut, as also suggested).     

If you can make some light orienting marks on the switch before removal, it will allow you to test it again after it is out...maybe just a line on the side, make note of how it lines up.    It almost HAS to be a NO switch, which grounds the trace running up the middle to the ground plane.

I have found the bulb sucker to be enough, YMMV tho.  Don't hold the iron on the pad for too long! 

[duck_arse]

erm, can we back up a little? do you not want to just bypass the bypassing circuit w/ a clunk-clunk footswitch? as per RG's article, you don't need to mess w/ the switch section, you only really need to find where the signal in's and out's the switching section, and wire thse points to the hard bypass switch.

D2, 3, 4 will most likely connect to the switch fets, so follow those tracks.

from looking at the board, the upper two contacts switch with the lower two contacts when pressed (NO or NC, who knows?). the easiest way around that switch would be to cut that long trace up beside the red blob.

[rbarone]

Thanks Duck -  Are you saying that I don't necessarily need to remove the original switch, but instead, just by-pass it?

[duck_arse]

I will say that if you want me to.