Maplin alpha dpdt small size foot switches

[numpty]

I would like to warn people about using these in their stomp boxes, as switch contacts fail after a short time of usage. Grease in the in the upper chamber( where the plunger is) eventually gets forced downwards into the contacts causing intermittent electrical contact.I'm not sure whether this is a problem if used at the higher current flow and voltages for which they were designed for but it certainly is in a stomp box context. Even careful soldering won't stop this, as they pack far to much grease for the job into them.

[k_laakso]

I used those switches in my first projects, and they have failed one by one.. got quite pissed when three broke at the same time... And the werent even cheap..

[drewl]

Found this problem with some Fulltone switches.
Can you take them apart and clean out the grease?

[numpty]

I have dismantled them, thats how i found out about the grease problem. They are difficult to reassemble as there are tiny plastic plungers ,springs and rockerlinkage which are hard to align.But  I did degrease it and managed to reassemble it and it worked, but casing was a bit loose, so it didn't seem as if it would be that reliable after that.I tried a some super glue on the case but it got inside and glued the guts together, so I bined it!

[drewl]

Some of the cheaper switches have 4 metal tabs with flanges that hold the plastic casing together.
I've had good success by wrapping a piece of buss wire around the switch and soldering it in place to hold the whole thing together.

[Mick Bailey]

Just bought quite a few of these from Rapid. Bummer...............

At least they're only £1.40 there.

[zombiwoof]

On a related note, how do those Taiwanese copies of the old Arrow X-wing  DPDT's hold up?  I notice that the descriptions of them always seem to suggest that they may not be the best for reliability.

Al

[Dragonfly]

are those the same as these ones that small bear sells ?

http://www.smallbearelec.com/Detail.bok?no=23&sfs=9ebd0571

[earthtonesaudio]

On a related note, how do those Taiwanese copies of the old Arrow X-wing  DPDT's hold up?  I notice that the descriptions of them always seem to suggest that they may not be the best for reliability.

Al

I have one that's about 4 months old (used about 2x/week) that has become intermittent.   

are those the same as these ones that small bear sells ?

http://www.smallbearelec.com/Detail.bok?no=23&sfs=9ebd0571

Looks like the ones the OP is talking about.  Maplin stocks them, anyway: http://www.maplin.co.uk/module.aspx?ModuleNo=35032&doy=27m3
NOTE: these are different from the Taiwanese X-wing variety.  I thought they were supposed to be more durable than the x-wings...?


I'd like to know an actual number of switches that have people seen fail?  One or two doesn't necessarily mean it's a defect, but a couple dozen might.  Also if you are like me, the first couple switches you wired up may have been slightly overheated due to poor soldering technique.    I actually melted a contact off an x-wing, then reheated it and shoved it back in (that might have something to do with why it is intermittent now).

[Mick Bailey]

Alpha must have sold millions of these switches over the years - wonder if this is a batch problem? I haven't had one fail (yet.......) I like them because of their small size.

[Mark Hammer]

I have posted about this more times than I care to remember.

The grease holds the rocker contact in place during assembly.  I imagine it also serves to damp and stabiize movement of the rocker contact so that switching is less "jittery".  But it is NOT required for the switch to function electronically.

The failure rate implied in this thread is excessively high.  Higher than any large manufacturer could tolerate and still be in business.  So how is it that a company could produce a switch with this high a failure rate and still have customers?  Because their commercial clients don't have the same failure rate that we hobbyists do. 

So why do us hobbyists have such a high failure rate and commercial clients don't?  Because they will use highly efficient soldering techniques and we apply heat to the joint for so long that the grease liquifies and spreads out over the surface of the rocker contact, creating a barrier for proper electrical contact internally.

So what can you do about it?  Simple.  When you go to solder the lugs on the outside: 1) if it is possible, make sure the lug you are soldering is not in electrical (hence thermal) contact with anything else, 2) WAIT between soldering the additional lugs so that there is no heat buildup, 3) pre-tin the lugs and whatever wires you are going to solder to the lugs so that the eventual joint is produced quickly.  A bit of liquid flux and a higher heat iron helps a lot.

Worse comes to worse, you CAN gently pry the tabs off the switch chassis, and clean the grease off the rocker contacts with some alchohol.  That will restore contact capability.  Just don't lose any parts in the process.

[numpty]

I was aware of this when I soldered the switch and hopefully avoided excessive heat build-up .However about a year later or so, they failed, but not from excessive usage.I still think that the plunger forces grease downwards. The grease is for lubrication only so a tiny amount is required, the switch I opened was packed with the stuff. Maybe its best to avoid this type of switch as there many others to choose from, although i live in the uk, I will be trying Aron's next.

[spudulike]

Used these regularly for Vex-style enclosures (ie 1590 used sideways so space is an issue) - no failures yet.
All gigged, oldest one is 2yrs now.
Odd.