Switching woes

[ed]

Hello everyone,
I know this has been discussed a lot but here goes:
I have built a few effects with the help of a friend and have consistent switch pop so I guess I must be doing something wrong. For example this great layout by Mark : http://tagboardeffects.blogspot.gr/2014/05/skrydstrup-r-overdrive-odr-2.html
I've built the buffered version however the switch is popping. I've tried several 3pdt's and a few relay-switches to no avail. I've read a lot on the subject and tried some things but still can't figure the cause. Any suggestion would be greatly appreciated.
Thanks

[Beaker]

There is a thread titled "Switch popping" on page 2 of this forum. Worth a read before you proceed any further.

[ed]

Thanks Beaker, I've already read the thread and I'm pretty sure my situation is different. I measured dc at the jacks and it's pretty much zero. In my case the pop is louder when switching off (output mismatch?).

[Beaker]

Best thing to do is post up a picture of the inside of your pedal. We may be able to spot something.

[ed]

Ok, here goes :


thanks for taking the time.

[Silver Blues]

If that's your pulldown resistor mounted directly to the jack, this actually doesn't achieve anything - it must be directly at the circuit input after the switch.

Nice build though, it's quite nice and neat. I'm also going to give you the tip I always give people, don't try and solder your links to the copper on the bottom of the board, install them top-down and solder the free ends as if they were components. It makes life so much easier and lessens the possibility of error or improper joints.

[Beaker]

Not to mention accidental short circuits if the insulation melts or gets cut.

Which switch wiring scheme are you using? I can't quite work out what wire is going where.

Also what brand or type of switch are you using as I don't recognise it?

[ed]

Thanks Silver. I put the resistor at the output jack as it is on the original (so that it is part of the buffer -always after the effect- whether the effect is engaged or not. Thanks for the tip.

[ed]

I'm using the wiring scheme that Mark suggests for buffered bypass on the link in my first post:
"The input socket connects directly to the input of the bypass buffer.  The output of the bypass buffer then goes to ODR-2 input and daisy chains to the 3PDT stomp switch, lugs 1 and 4.  The output of the ODR-2 will go to 3PDT lugs 3 and 6, and the output socket connects to 3PDT lugs 2 and 5."
I don't know the brand of the switch; it is a generic 3pdt probably of Chinese origin with a smaller boby and softer switching. I've tried a few different 3pdt's with no difference in noise whatsoever.

[Beaker]

Oh yeah, the empty lug because you are not using an LED threw me.

So if you tried different types of switch, it's not that then.

One suggestion is to try wiring an extra ground wire between the input jack ground lug, to the output jack ground lug. It is generally seen as good practise in pedals, eliminating the possibility of one or both jacks becoming isolated from the enclosure (if they work loose or if you have paint build up around the holes). This can be another source of either humming or switch popping.

[ed]

Actually, I am using an LED (it is mounted between the pots) on the last pole. I had the extra wire from the input jack ground to output jack ground and removed it just to hear if it makes any difference (it didn't).
Jacks are pretty tight. Thanks for keeping up with me.

[Ciaran Haslett]

Hey Ed

I had some popping problems with the Heartthrob Tremolo.  I ended up putting pulldown resistors on the switch lugs at both circuit input and output to stop it.  Worked a treat!  Although your situation is much different.

You could try rewiring the switch to ground the OD output like this

but I've no idea what that would do to your input signal

You could go all out and wire up Pulldown resistors everywhere or add (more) blocking caps in series with all circuit outputs.

Bear in mind though...I have next to no idea what I'm talking about!!

Good luck

[ed]

Ciaran,
thanks for the suggestion but I've already tried this. I have pulldown resistors both at the input and output. However, I noticed that when the effect is switched on or off, the DMM's voltage reading at the jacks momentarily jumps and then drops back to zero. Is this normal? Maybe a case of leaky electrolytics, I don't really know.