How to describe this switch for finding replacement? - Page 1
Forum section: electronics / projects

author: Skyfox
author_rank: Regular Contributor
timestamp: March 03, 2018, 10:31:47 pm
content: I sure seem to have a knack for working on repair projects that need parts that are impossible to find. It can never be a simple capacitor or something, huh? Anyway, I'm trying to find a DPDT pushbutton momentary switch and I can't find it anywhere. It's the first attached picture, the one with the silver body and yellow plunger. As you can see, the pins come out at a right angle to the direction of the plunger, and follow another right angle to be pointing back the same direction of the plunger. It's so when it's mounted on the board, the plunger can stick out through a hole in the opposite direction. It says MSC but there is no other part number or description on it.The closest description I've found for the mounting type is through hole right angle vertical (Digikey's description). But that results in switches that look like the second attached picture, with the red body. As you can see, the pins come out the back in line with the plunger, and then make a right angle so that when it's mounted on the board the plunger sits parallel to the board. This isn't what I need at all, and I can't even find a switch style where the pins come out straight out the bottom of the switch at a right angle to the plunger so I can bend them myself.Anyway, how would I describe my switch for searching purposes? I've tried looking for "180°", "double right angle", "opposite", "reverse", and "down", but turned up nothing. I've also looked on Digikey, Mouser, MCM Electronics, Jaycar, Jameco, Tayda, Ebay, Amazon, and a few other sources and didn't find what I'm looking for.

author: Gyro
author_rank: Super Contributor
timestamp: March 03, 2018, 10:36:17 pm
content: Wow, that's an unusual one! What's the problem with it?Fixing might be an easier alternative, especially if it is momentary action.

author: Gregg
author_rank: Super Contributor
timestamp: March 04, 2018, 12:11:38 am
content: I would first try carefully taking it apart and if it is not repairable find something like these:https://www.ebay.com/itm/2-Pack-DPDT-Push-Button-Switch-Alternate-Action-PC-Mount-18017/281549869808clip the leads off the old switch near the body and solder them to the new switch.

author: danadak
author_rank: Super Contributor
timestamp: March 04, 2018, 12:51:52 am
content: Use one of these, something similar, and make your own leadformpieces to solder onto its pins .....Regards, Dana.

author: Skyfox
author_rank: Regular Contributor
timestamp: March 04, 2018, 04:55:09 am
content: Gyro, the problem with it is the contacts were going out. It's the hook switch from a phone, and it was making only intermittent contact when the phone was off the hook, and when there was actual dial tone it was making tons of static.Gregg, good idea about doing some solder surgery with those replacement switches. Those ones you linked are the first ones I've found where the plunger is actually at a right angle to the leads, which is strange that it would be hard to find considering it makes the most sense in design for the plunger to be sliding inline with the internal contacts. Thanks for the link!

author: Gyro
author_rank: Super Contributor
timestamp: March 04, 2018, 10:43:00 am
content: QuoteThat's what I suspected as you mentioned momentary action - with alternate action, mechanical wear of the mechanism would have been the other possible failure mode.The contacts on those switches are fairly robust and basic, probably without any specific contact platings and prone to oxidation. I think you have a very good chance of a lasting fix with some decent switch cleaner - you should be able to work it in along the plunger axis of the switch with repeated actuations. You can clean off any excess before re-fitting. Caig Deoxit seems to be the most popular around here.If the moving contact pressure really has got bad, then try finding a switch of the same make or construction, dismantle by bending the tabs and use it for donor parts, just keeping the base board with its leadframe.

author: texaspyro
author_rank: Super Contributor
timestamp: March 05, 2018, 04:41:20 am
content: Carefully drill a small hole into one side of the switch (use a hand drill or pin vice, be careful to drill just deep enough to just clear the case material. Finding the best place to drill takes some intuition about where in order to avoid drilling into import stuff like contact pivot points.Clear shavings from the bit often, and drill with the drill bit pointing up into the case so drill shavings don't fall into the case). Then spray some contact cleaner / DeOxit into the hole. Cycle the switch a couple dozen times, shake out as much contact cleaner as you can, blow some canned air into the hole, shake it out again, and cover the hole with some tape. Works for sealed relays, too.

author: BrianHG
author_rank: Super Contributor
timestamp: March 05, 2018, 05:39:45 am
content: This looks closer, but, you just need to solder your own leads with good thick solid core wire to make it match your yellow button.https://www.digikey.com/product-detail/en/c-k/PN21LENA03QE/CKN1192-ND/262659

author: floobydust
author_rank: Super Contributor
timestamp: March 05, 2018, 05:53:16 am
content: Alps makes push switches.You can remove the cam to make a push on-push off, into a momentary action. Mouser carries some of them, eBay for the rest.

author: Skyfox
author_rank: Regular Contributor
timestamp: March 05, 2018, 04:19:25 pm
content: Thanks to everybody's input on this! I have looked into the push on-push off type that I could modify to make momentary, but still haven't found anything that would be a good replacement.The main question is still open, though: is there any specific or industry-standard description for the style of button in the picture where the leads are reversed to point in the same direction as the plunger?

author: westfw
author_rank: Super Contributor
timestamp: March 06, 2018, 09:26:04 am
content: Digikey has some tactile switches with "mounting style": "through-hole, reverse"But I don't see any other switch styles with a similar description.

author: Skyfox
author_rank: Regular Contributor
timestamp: March 06, 2018, 03:19:30 pm
content: Thanks for the info!

author: senso
author_rank: Frequent Contributor
timestamp: March 06, 2018, 04:03:29 pm
content: Quote from: texaspyro on March 05, 2018, 04:41:20 amEasier to just unhook the small 4 prongs and open the switch up, clean it, put back and fold them back again, its a 2 minute job.

author: texaspyro
author_rank: Super Contributor
timestamp: March 06, 2018, 06:08:56 pm
content: Quote from: senso on March 06, 2018, 04:03:29 pm