LED indicator causing clicks

[Peter Snowberg]

In high-speed digital land you simply cannot afford to skip the cleaning step. I've "repaired" many things simply by cleaning up old flux. Many fluxes absorb moisture with time so everything works great for months until....

[brett]

Hi.
What do you use to clean up?
This is a mystery to me.
(CMOS DILs scare me a bit by forcing close rails on high impedance devices.)\
What's best - ethanol, acetone, white spirits

[Peter Snowberg]

What's best - ethanol, acetone, white spirits

Yes.

It depends on the chemistry of the flux. Some fluxes are designed to clean up with hot water while others dissolve well in semi-polar solvents and some seem to want to cling on unless you use a non-polar solvent.

Grab a board and try what you have on hand with an old toothbrush.

I've used xylene and denatured alcohol with good success but it always seems to leave a thin coating unless there is serious washing.

Just about every chemical company that deals with electronics makes some sort of flux cleaner. These work really well.

Don't be scared by CMOS, just use good grounding procedure for your work area. Use a CMOS safe iron if you have a variable temp station, always wear a ground strap, and keep chips in anti-static rails or foam until ready to populate the board. The largest problems with CMOS chips and flux crud are almost always in oscillators, PLLs, or high impedance inputs with weak pull resistors.

[brett]

Thanks for the info on cleaning.  I'll get some acetone.  By the way, go easy on that xylene, it'll wipe out your liver or give you the big C.

Don't be scared by CMOS, just use good grounding procedure for your work area. Use a CMOS safe iron if you have a variable temp station, always wear a ground strap, and keep chips in anti-static rails or foam until ready to populate the board. The largest problems with CMOS chips and flux crud are almost always in oscillators, PLLs, or high impedance inputs with weak pull resistors.

You're kidding me, right.    Maybe not 

[The Tone God]

Thanks for the info on cleaning.  I'll get some acetone...

Acetone...bad.

http://www.diystompboxes.com/smfforum/index.php?topic=36309.0

Andrew

[Peter Snowberg]

As our Tone God just proclaimed, acetone is a bit too heavy duty. It works great for stripping lots of stuff, including some component packaging. It will dissolve a few too many things.

Xylene is much less aggressive but you still have to watch it around plastic. The same goes for denatured alcohol.

Commercial flux stripper goes to work on the flux but leaves almost everything else untouched.

[formerMember1]

outside the box.... that's the ticket.

I have tried all the split resistor etc methods above years ago, and they almost always don't work. Same with the problem of using the input jack ring for battery ground - if you plug into the power jack that connection is not used, and the pedal still pops, so that idea won't help. I have split grounds, even used different power supplies for LEDs and it's never easy. Keep on plugging and you will find something that works with ONE PEDAL, but it won't work for your next circuit though

Thank gosh you said this.  Becuase i have tried those things also and they don't do anything IMHO too.   I started to wonder why I was having these popping problems with LED's and no one else did for awhile now! But i see others too have the same problems... I even used Grounded input and that didn't do it either. 

[jrc4558]

a) we trust builders who post here. we dont trust just any builders. i think its obvious why
b) so would it be better to use solder w/o the rosin core and just dip the iron into the separate rosin while soldering? (i am doing so with tube amps, because the diameter of the fine electronics solder is too small to fill one eyelet w/o rolling off a couple of feet)

[Connoisseur of Distortion]

this is interesting. what kind of resistance will a 'flux trace' have? enough to mess with biasing in a JFET pedal??

[zachary vex]

to test  your theory, if you have one, use a small screwdriver to simply scrape away the flux between the connections.

[Peter Snowberg]

JFETs have an input impedance in the many teraohms range. Flux residue has a lower resistance.

It's not the flux so much as it is the carbonized remains of flux.

[grapefruit]

I tried a single transistor circuit to slow down the switching signal. There's a circuit and description for it here...

http://members.optusnet.com.au/~stewpye/bypass_switching.htm

I don't have a pedal here that has the led current popping problem to try it out with but the waveform looked smooth on the cro. Hopefully someone can try it out and let me know how it goes. Yeah my website sucks. I'd never tried to do one until today.

Stew.

[amz-fx]

I tried a single transistor circuit to slow down the switching signal. There's a circuit and description for it here...

I did one of these as well, but with a mosfet...  I haven't tested it yet:



regards, Jack

[gez]

Hope this doesn't come across as rude, but doesn't this defeat the object of the exercise?  One might as well use a DPDT switch with RG's millennium circuit (simpler/cheaper). 

[Unbeliever]

.... or the high-brightness LED + large series resistor? Even if the LED is $1 instead of 0.10c then...

[amz-fx]

Hope this doesn't come across as rude, but doesn't this defeat the object of the exercise?  One might as well use a DPDT switch with RG's millennium circuit (simpler/cheaper).

This is a slow-on/slow-off click reduction circuit, not just a switcher, that I designed as I was working on the article, just for info.

The DPDT Rat-type switching could be used with a slight mod of the circuit but it might still pop or click.  Here is an example of how it would be wired:



regards, Jack

[gez]

This is a slow-on/slow-off click reduction circuit, not just a switcher, that I designed as I was working on the article, just for info.

Understood, but my own (limited) experience of RG's circuit is that leakage and gate capacitance gives you slightly slower turn on too.  All good stuff though, and thanks for sharing your ideas...and others. 

[Paul Marossy]

We started getting POPPING problems on a pedal that we have sold hundreds of with no problems.
Bad switches? I was able to mearure a voltage on the switch, bleeding though from the LED switch contact.
I studied and found the only change was solder... I had ordered
water soluble flux type solder by mistake. Cleaning off the flux stopped the popping.
Threw the solder in the garbage. Don't buy that solder!

Just something to add this. I have traced several malfunctioning circuits to the solder flux itself being the problem. I even fixed my friend's 3-channel Mesa Boogie Nomad that wouldn't switch channels properly - you could hear the relay clicking back and forth, but it wouldn't change channels properly. All I did was take out the footswitch PCB from the housing and cleaned off the BIG blobs of flux around the LEDs and it was fixed! A year ago, I would have never thought something like that was possible! 

[gez]

I don't normally use LEDs and the last time I did the circuit didn't use true bypass so none of this was an issue.  But, for my next box...

Soooo, I ordered the brightest LED Rapid had - 10000 mcd - and tried it out today.  It's down as orange in the catalogue but, thankfully, glows red.  With a 47k stop resistor it's bright enough for my needs. 

Thanks for the info Zachary, much appreciated! 

[puretube]

did I "heard that"?