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Cleaning Pushbuttons on sx-1250 (and others)

rsmcatskills

rsmcatskills

New Member
I'm in the bowels of the beast now cleaning the switches. Those pushbutton function and filter switches are a challenge and I walked away after completely ripping apart 1 of them saying I don't think I ever want to do this again. But, it was a learning experience. Can I assume that that is not normal SOP and all cleaning is standardly done without taking the switch apart down to the copper slides and Deoxit and lube from outside are sufficient ? However, it did enable me to polish the contacts and the copper slides. I don't see that I accomplished all that much and the risk far parts loss and or damage is pretty high. Time to do all those switches would be pretty high. Thoughts anyone.
 
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Welcome to the restorers club grasshopper. Don't forget to use preserv-it on them to hold onto all your hard work longer.

If you have to ship a unit after doing just a deoxiting there is the certainty that some of the contacts will be jarred by shipping and stop riding in the clean grooves the deoxit plowed through the corrosion on the stationary contacts. Then they have to be either worked until they regain the clean path, or the new path is deoxit plowed.

IF the unit is a personal one that will be treated gently, then you can probably get away with just deoxiting.

Yes it takes a long time and a light touch to do that without destroying them. Desoldering them from the board, disassembling them such that there is no damage and they can be reassembled, getting the corrosion off the contact metal, reassembling everything, TESTING the contact resistance BEFORE reinstalling them (it's far easier to correct problems at this point rather than later) while actuating them multiple times to be sure they make consistent contact. To get accurate resistances (20 milliohms), use 4 wire (Kelvin contacts) ohms, where the current is carried through one set of contacts and the voltage is read

Tip: the sliders have only one useable contact area, so deoxit plowing on THEM is the preferred method, after the stationary contacts are back to bare metal.

Observation: THAT'S why I have an ultrasonic cleaner.
 
Ok ... I have kelvin clip milliohm meter at work that I have access to so I can do that. Can I ask - on the one I disassembled I needed to bend 4 little tabs that hold the plastic "top" at the front of the switch to get the guts out... is that correct- seems a little archaic.
 
rsmcatskills said:
Ok ... I have kelvin clip milliohm meter at work that I have access to so I can do that. Can I ask - on the one I disassembled I needed to bend 4 little tabs that hold the plastic "top" at the front of the switch to get the guts out... is that correct- seems a little archaic.
Click to expand...

Yup, carefully bend them, they really weren't intended to be disassembled.
suitekids said:
Observation: THAT'S why I have an ultrasonic cleaner.

What is the solution in the ultrasonic cleaner?
Click to expand...
It is different for different contact materials. And they are toxic. I do have some chemical engineering education (engineering core curriculum, it was enough).
Then they have to be neutralized by other solutions, and then finally cleaned and then ultrasonically rinsed with condensed steam.
If I had a DI water still I would use that with it's high electrical resistance water.
The contacts don't look great and shiny (corrosion does that, and mechanical polishing, even pencil erasers, removes material, and with flashed as opposed to plated contacts, there's little to spare), but they measure out well.

There were some nasty threads / post wars with management about AK's liability when people started to post their own DIY cleaning brews before Deoxit came on scene. Nasty toxic, DANGEROUS stuff. Don't want to tear open all of those old scars.
 
I see, similar to the watch cleaning process, a solvent bath, then a neutralizing bath, then a type of water wetter dryer, then a trip to the oven, It smelled like carbon tet in the first bath, very dangerous stuff
 
I had a 1010 a few years back with the Phono function switches acting up. Still causing issues I had nothing to lose, so I tore into them and did the MTF treatment (Not the ultrasonic). Wow! I did every switch on that unit and Bam!
Single biggest difference to that restoration. It's now a must (For me) for a top notch restore, it's some work but well worth it. Bar none!
 
My 1010 gave me a fit too with all those push buttons right under the dial, dust and dirt magnets, hardest one to clean thus far, little shelves to catch everything air born, I also have half a dozen spare board that maybe I'll pull the push button switches off the board and practice on dis/re assembly. Can't hurt right?
 
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I spent 3 hrs tonight and got 4 done- some learning curve involved but like anything else you find little tricks as you go. I'm wondering why I don't just replace them - looks like there are lots of Alps switches out there. After looking at the ones I cleaned under a stereo scope I can tell that they might get tolerable but they will never be perfect. MFT advice was good to check with a 4 lead micro-ohmmeter - I would have put together one of them with the slider spread slightly - was jumping up to 100mOhms . Boy those things are fragile and full of crap - Talking myself into looking for new ones - or at least replacements.
 
are there Alps exact replacements??? that would be just too cool, even at 20 bucks a pop, small price to pay in my opinion for what you get
 
Sure looks like it - Ill have to do a little home work when I get the time. I found some on Ebay and at Newark but I have to compare dimensions and I think Id want to rip one apart just to see how its made. I'll let you know
 
The push on and push off switches may be replaceable, but the interlocked gangs may not be possible. Not with over the counter / stocked at the distributor switches. Special runs maybe, to replicate the structures molded into the shaft - but that takes a $$ investment.

The thing to remember is that the switches are soldered to the board, then mount the U shaped frame, which THEN supports the board with threaded holes and screws. Thus there are multiple mechanical considerations. Probably not insurmountable but difficult. Yes, it would be nice to go with new switches...
 
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