Interesting stompswitch

[Mark Hammer]

I was trying to find out some info on a work-mates cheapie guitar amp so I could spruce it up for him.  The company is a Chinese manufacturer that produces amps under the name Meridian and Soundking.  While browsing their site, I found some DPDT stompswitches that look about the same quality as the X-wings but are for direct PSB mounting.  http://www.soundking.com/images/upfile/20058229573053646.jpg

http://www.soundking.com/index.asp

Could be useful for somebody here, maybe.  The lugs of the blue 3PDT types are regularly soldered to PCBs but they are not made for it expressly and there seems to be a certain awkwardness and inconvenience in trying to do it.  These seem more tailored to the desired outcome.

[A.S.P.]

http://www.diystompboxes.com/smfforum/index.php?topic=42860.msg401440#msg401440

[$uperpuma]

they look like the Alpha ones at MCM... they work pretty well...although I am not yet skilled enough for PCB mounted switches

[Pushtone]

I got 20 of them from a local supplier.

I was told they are the same ones used in the big Line 6 DL pedals.

They where cheap at $2.50 each but out of 20, four have failed.

They do not like to be soldered more than once. Soldering a second time caused one to die.
The other three died on their own.

Here's a pic of one inside an MXR EF next to a blue 3PDT from Aron.

[Mark Hammer]

1 in 5 failing is not something any manufacturer would tolerate, no matter how much they thought they could pull one over on the unsuspecting public.

My gut sense is that many of these "failures" are the result of the grease inside the switch being accidentally flowed over the surface of the contact due to excessive heat.  Keep in mind there is heat that melts the chassis, and heat that liquifies the grease without melting the plastic chassis.  I have personally taken several "failed" stompswitches apart, wiped the grease coating off the rocker contacts, reassembled the switch, and been rewarded with dependable performance thereafter.

This is NOT a design flaw.  Rather it is a mismatch between the needs of the manufacturer and the construction methods of the hobbyist.  The grease inside the switches appears intended to briefly hold the rocker contacts in place during assembly, reducing "fumbling around time" and thereby cutting production costs.  When used with rapid industrial soldering techniques and adequate cooling, the grease poses no problem, or at least not nearly as often as 1 in 5.  When used by hobbyists, whose 25W handheld Weller may apply just a tad too much heat for a few seconds too long, the grease melts and coats the contacts, resulting in very poor contact...what we call failure.

It really doesn't take all that much to make a consistent and reliable switch, and no manufacturer could last long with the sorts of investment capital required if they couldn't turn out such a product.  The source of product difficulties DOES lie in the product occasionally, but more often in how we try to use it.  If there is any blame to be accorded, it is that we often lack sufficient information to use the product appropriately, and that is probably because such information is supplied to commercial clients but not to individual hobbyist users.

[Pushtone]

Mark, I remember your original post about the grease in footswitches.
When the first one died I was eager to take it apart to look for grease.
I could not detect any build up. Perhaps a film of grease but hard to tell if its there at all.

Also three of the switches died on their own, not during soldering, but several months
after in a working pedal. They died a little at a time.

For awhile they were fine in pedals. Then they would sometimes kill the signal
when switched. Stomping it again would bring it back.
Eventually they died by not working in one of its two positions. No amount of stomping would bring it back.

I returned the four and they were replaced by the same switch but now they have the red dot of epoxy around the lug
just like Aron's. (Wonder were they got that idea?) I haven't used these new ones yet.

I also have seen the same looking switch, I think by CLIFF, but its blue, like the Aron's 3PDT.

Since these footswitches were made for 120V vacuum cleaners I have wondered if they could be "burned in" in a rig that would pump
300v at 6 amps. That should heat them up enough to flow the grease. I've mentioned this before. 

[Mark Hammer]

When the first one died I was eager to take it apart to look for grease.
I could not detect any build up. Perhaps a film of grease but hard to tell if its there at all.

Also three of the switches died on their own, not during soldering, but several months
after in a working pedal. They died a little at a time.

For awhile they were fine in pedals. Then they would sometimes kill the signal
when switched. Stomping it again would bring it back.
Eventually they died by not working in one of its two positions. No amount of stomping would bring it back.

fair enough.  So now the question this prompts is "What process or mechanisms would lead to that sort of 'clinical history' ?".  If you've taken the switch apart, you realize the mechanism ain't that complicated.

One possibility is that the plastic housing which the rocker contacts sit in is somehow deformed over time such that when it does its see-saw motions it does not come to rest with good contact on one of the side contacts.  It might also be the case that the coating you looked for on the rocker contacts is not the only source of impeded contact.  I clean not only the rockers but the side and common contacts the rockers rest on.  Then I dab them with some of that Stabilant stuff I keep going on and on about.

Another possibility is that the contacts suffer some sort of mild corrosion or buildup of other coatings that otherwise impede good contact.  That may result from environmental conditions as much as the construction and composition of the switches themselves.

[Pushtone]

My supplier claims it was a bad batch and they didn't have issues before this lot.
They complained to their Taiwanese manufacturer and thats when they started to add the red epoxy.
This is the story I got. Time will tell.

I have to give them the benefit of the doubt because they also sell me 1/4" jacks for .78 cents!
And that's one sweet plum!

[darron]

carling makes those... i thought they'd be pretty popular and well known

http://push-button-switches.carlingtech.com/heavy-duty-pushbutton-switch__64.asp