Microswitch cleaner advice.

Thread Starter

SteveHow

Joined Jul 2, 2012
80
Hi,

I am restoring a Fostex DMT-8 Multitrack recorder and a few of the micro switches are intermittent. I believe its due to age as its a couple of the most used controller switches namely STOP.

I was wondering if anyone would recommend a good contact cleaner that might be worth trying rather than replacement as it's quite a job doing so. I might add that I am reluctant using any solvents as last time I did use a so called "contact cleaner" in a POT it seemed to have dunked it up making it sticky. ( it was never slide smoothly again). So I am after a proven well known product that really does work. (If possible)

20180327_204205.jpg
 
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AlbertHall

Joined Jun 4, 2014
11,533
I don't think you will get any kind of switch cleaner into that kind of switch so I fear the only option is replacement. It looks like this board doesn't have plated through holes so replacement isn't too difficult.
 

Reloadron

Joined Jan 15, 2015
6,137
I don't think you will get any kind of switch cleaner into that kind of switch so I fear the only option is replacement. It looks like this board doesn't have plated through holes so replacement isn't too difficult.
That would also be my thinking. Most contact cleaners will likely react with the rubber membrane materiel and destroy the switches. Removing and replacing is not that difficult and switches like this are not really designed to be "cleaned".

The switches are more commonly called Tactile Switches and are relatively inexpensive. Here is an example of a mixed size package on Amazon for under $10 USD. Actually next time the wife does Amazon I should get that package just so I have some. :)

Ron
 

AlbertHall

Joined Jun 4, 2014
11,533
On replacement ensure they are all oriented the same way otherwise observe the orientation on removal, else the SW will be permanently ON!!;)
Max.
The ones I have come across have the pins in a rectangle not a square and so if the pins fit the board they are the right way round. 180 degrees rotation is OK, 90 degrees is not.
 

ebp

Joined Feb 8, 2018
2,332
Assuming the vacant positions are the same as for the actual switches, those switches are somewhat oddball by current standards, since they have only 2 pins. Most of the currently popular types are 4 pins - they have what amount to built-in "jumpers" to facilitate PCB layout.
 

AlbertHall

Joined Jun 4, 2014
11,533
Assuming the vacant positions are the same as for the actual switches, those switches are somewhat oddball by current standards, since they have only 2 pins. Most of the currently popular types are 4 pins - they have what amount to built-in "jumpers" to facilitate PCB layout.
You may be right. I can't see the pins around the sides of the switches which you normally can.

There are some 2 pin switches available
 

KJ6EAD

Joined Apr 30, 2011
1,581
The intermittency may be the result of actual switch failure but it's equally likely to be solder failure. The solder joints of PCB-mounted pushbutton switches, especially on unsupported portions of the PCB, are prone to cracking from repeated board flexure.

Assuming the vacant positions are the same as for the actual switches, those switches are somewhat oddball by current standards, since they have only 2 pins. Most of the currently popular types are 4 pins - they have what amount to built-in "jumpers" to facilitate PCB layout.
On replacement ensure they are all oriented the same way otherwise observe the orientation on removal, else the SW will be permanently ON!!;)
Max.
…and the remaining switches on the row or column stop working because you lose the jumper.
 
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MisterBill2

Joined Jan 23, 2018
9,526
"Contact Cleaner" is for removing the gunk that builds up on motor starter contacts. never use it on electronics. If you can find CONTROL cleaner that is safer, but on many occasions I have had success with plain denatured alcohol .
 

MrChips

Joined Oct 2, 2009
24,452
There a 2-pin versions and there are 4-pin versions. The 4-pin push-buttons I have encountered are not on a square footprint. Hence you should not have a problem when replacing on a PCB.

When prototyping, you can easily make a mistake and connect the wrong legs.

upload_2018-3-30_14-47-41.jpeg

 
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