Fix a Stuck Sliding Switch

[Reaper]

I recently picked up a Panasonic RC-95 clock radio. I love old VFD clocks, and this one is really nice! While not a flip clock, the part I'm having trouble with is also used in the older clocks.

I just finished restoring the clock, and everything works great. The switches were very dirty and making poor contact, so I cleaned them with contact cleaner. Now they function properly but some of them are very stiff to move. If I move them by only touching the side of the switch they are easier to move, but if I'm pressing down on them at all they are very stiff. I have some dielectric silicone lubricant with PTFE, so I put a small drop of that on the ball bearings on the side of each switch. That helped a little but they were still stiff, so I put a small amount on the switch contacts and worked the switches back and forth. They are more usable now, but still stiff. Is there any way to fix these switches, or are they just heavily worn?

[gschmidt958]

I've taken apart switches with mixed success, sometimes I have ruined them. If you care to go further, I found this on EEVblog.

Re: Electronic's knob would like to fix possible broken radio slider switch

« Reply Groups on: March 01, 2022, 05:49:10 pm »
CAUTION: If this is the first time you're attempting to take a switch apart to service it I'd give better than even odds on you making it worse!

If that's the type with two open ends, it should be possible to desolder it and bend the sides out slightly to free the Paxolin base plate. You'll find two contacts in recesses in the bottom of the slide actuator, which will probably drop out of their slots, and may even stay on the fixed contacts staked through the baseplate. Beware of the spring detent mechanism jumping out - there may be a tiny ball bearing with a spring behind it in a hole in the side of the actuator.

Nothing can be done to service the contacts other than carefully cleaning them and possibly squeezing the moving contacts slightly if wear has made them too loose on the fixed contacts. The inside of the shell can be cleaned with a mild abrasive to remove corrosion.
Use PTFE dry lube on the inside of the shell and a trace of plastic compatible non-silicone dielectric grease on the contacts and detent mechanism. Reassemble carefully, checking the baseplate is fully seated and the slider slides, before nipping up the sides to retain the baseplate.

[Reaper]

Yes, it's the sliding type with two open ends. I sprayed contact cleaner in both ends and got the switches working well with regards to contact. However they are very stiff when trying to move them. If you're pressing down on the switch while sliding they get stuck sometimes, and it almost feels like you're going to break something from pressing so hard.

I greased the contacts and ball bearing, maybe I should try greasing the entire inside of the switch casing. The oil I'm using is dielectric and plastic safe, so it shouldn't hurt anything. I have a thicker version of the grease I'm using, it's as thick as vaseline. Maybe that would work better than the lighter oil.

I didn't want to try messing with the switches. If I break one I won't be able to get a replacement easily. The switches on top of the clock don't have the normal rectangular handle, they have a unique shape to the switch. Almost like a long toggle switch. I wanted to keep the aesthetics of the clock original if possible.

[Reaper]

So I took the thicker dielectric grease I had and dipped a piece of solid wire in it. Then I poked the wire through the slot in the switch. I was able to grease the area between the bottom of the switch and the top of the contacts without disassembling the switch. I also put a bit more grease around the ball bearing on the side of the switch. I did this with all of the switches and they move easier now. Still not perfect, but easier to move than before.

This is probably the best I can do without replacing the switches, but the clock is definitely usable now. The switches are still slightly stiff but they work OK.