HP45 power switch lubrication without opening calculator?

[calc-calcs]

I do have a minty fully operational HP45, no keyboard bounces whatsoever, everything works perfectly, and immaculate battery contacts. Calculator being used with an aftermarket 3xAAA waterhosko battery holder with Panasonic/Eneloop cells, and keeping/charging battery outside of the calculator when not in use. It gets some use once in a while, but nothing really that much on a regular basis.

The only minor issue, if it can be called that, is that I have noticed on this calculator since I got it about 3 years ago that the power switch seems to need slightly more force to make it slide to the on or off positions. Switch action is always very positive and there seems to be no bad contact at any point at power on/off. Drag is not really that much like it feels excessive, but I had other classics over the years and I don't recall the power switch being as stiff as this one. Although really something one can live with unless the calculator would be used on a every day basis. I am just mildly concerned that this added drag might be indicative of added wear and tear on the switch.

Question is, anybody else encountered this situation? Would it be advisable or even possible to "slip in" a bit of lubrication to the switch through the front panel opening? so as not to have to peel off the back label (also in mint condition) in order to open up the calculator. And if so, what to use for lubrication? (The usual Deoxit D100?).

The last question would be, is it possible that this slight stiffness might be actually due to lack of use for some time before I got it, or perhaps even lack of use since new? The calculator has the obvious signs of normal use in that the silver stripe above the switch is somewhat worn out in the usual manner, although on this one the wear seems to be less pronounced compared to other HP calculators of about the same vintage I've seen out there.

Thanks.

EDIT: correct spelling, add info.

[teenix]

The switch is quite basic in operation.

A contact connects via rounded edges onto the plated circuit board pads and fits into a recess under the switch moulding. It is bent in such a way as to provide outward pressure onto the board when assembled.

The plastic switch (from memory) slides over a plastic protrusion tensioned by the spring contact which gives it the snap on, snap off feel. I doubt the board contact would offer much resistance to movement although thick grime can build up over time.

Rather than just push it sideways, you can push down slightly on the switch as you move it from off - on - off and this will relieve pressure on the switch to the underside of the case which reduces the "snap" to off or on.

I don't think they were manufactured with any, but maybe a tiny bit of lubricant on the plastic applied as you mention may reduce the drag between the switch and the underside of the case top, but I'd be careful about too much.

Not sure about which type of lubricant though, something that doesn't hurt plastic and won't dribble onto the circuit board underneath.

Other than that, it might just need a clean up.

cheers

Tony

[calc-calcs]

Yes by applying slight downward pressure (very carefully) the switch resistance almost goes away. There is actually not much inward travel but it seems to be enough to make things slide easier. Thanks for the suggestion.

I wish there was an easy way to access the switch to do a cleanup/maintenance. Can't open these calculators up without at least having to bend up the corners of the back label that covers two screws. And I am definitively trying to avoid that.

Years ago I had another 45 that needed a good general cleaning inside and out, only this one had already been opened before so no big deal. I took it all apart, even the keyboard, washed and cleaned all the keys etc. I seem to remember that the power switch contacts slide directly over two pads on the circuit board, and the switch was lubed with silicone grease.

[g8241CV]

IIRC I used DeOxit on my HP-35 switch as a two-fer (lube, attempt at contact cleaning) with no ill-effect, some smoothing of the action. Small amount. No expert, and may be wrong. Just suggesting.

[rprosperi]

DeOxit (Red) is an excellent cleaner, and good to use to ensure your contacts are clean, but not a long-term lubricant.

Use a lubricant made for electronics, such as Lubriplate (found on eBay, Amazon, etc.) and yes you can simply (carefully of course) put a small amount into the power switch slot and work it in by simply sliding the switch back and forth (but remove power when you do this, there's no reason to stress electronics with 50 on/off cycles).

It could be a bit messy, as it's more of an ointment than a liquid, so be sure to clean up the surrounding face and also the exposed area inside the switch slot, to prevent accumulation of dust into the greased area.

[GreyUser]

While you could use some thin viscosity plastic safe lubricant, as mentioned, it will make a mess of things and you risk finish loss on the case area surrounding the switch. I’ve done it and while it kind of sort of works, it’s just not worth the risk IMO.

HP did lubricate the metal to metal switch contact area with a white grease. There was no lubrication on the plastic slider. What happens over time is that dirt works its way into the slide openings and creates wear on the two locking ridges on the slide and in the track area molding in the case top. That dirt now inside the slider area creates wear tracks in the case top which increases the friction of the slide, leaving you right where you describe, it takes more force to operate the switch than originally required.

The best solution is to buy a replacement label, pop it open, clean and lubricate things and reassemble leaving out the two screws under the label so that it is easy to open in the future. I always leave the screws out of the units I’ve repaired, the case bottoms are so stiff you’ll never know the screws are missing.

FYI, you can lift the top corners of the original label with minimal scaring to get the two screws out, it’s well described in forum posts here and in the old forum content.

One last thing. On the classics without card readers, there is zero danger recharging the batteries in the calculator - as the battery is isolated from the calculator when the charger plug is in place. It’s a different story with the 65 and 67. The card reader chip in the 67 is supposed to withstand an open battery but I wouldn’t trust that feature with some forty years of age.

[burkhard]

(10-04-2020 04:11 PM)rprosperi Wrote:  Use a lubricant made for electronics, such as Lubriplate (found on eBay, Amazon, etc.) and yes you can simply (carefully of course) put a small amount into the power switch slot and work it in by simply sliding the switch back and forth (but remove power when you do this, there's no reason to stress electronics with 50 on/off cycles).

A point of clarification here. "Lubriplate" is a brand that makes MANY different products, most of which you don't want to put on electrical switches. Their flagship product which they have sold for many decades and the one that you will get if you use that generically just say "Lubriplate" to a guy at an autoparts store is one of these. It's for car door hinges, windshield wiper mechanisms, and the like.

The specific Lubriplate product I believe Bob is advocating is their DS-ES grease, which is a fairly specialty item, but easy to find online. Here's the link to it on the Lubriplate web site.
https://www.lubriplate.com/Consumer/Cons...name=DS-ES
I've used this myself in the manner he suggests on Classic series calculators and it works.

[AndiGer]

I also have a 45 with a power switch that moves a little hard. If I press it slightly inward to switch on/off the calculator it moves smoothly. I never concerned about. Serial is 1349S5... Maybe it depends on the production series.

[calc-calcs]

GreyUser:

Yes that makes a lot of sense of dust getting into the works over time, thank you for the detailed explanation about the mechanical switch operation. Guess eventually will have to open up the calculator when things get too tight, but for now a solution seems to be to slightly press down on the switch while flipping it. Besides, it will not be seeing a lot of everyday use anyhow. And after rethinking it, I also agree that probably not a good idea to try getting some lubrication into the switch through the top slot.

Interesting idea about leaving out the two screws under the label, should be OK as long as the calculator stays safely on a desk and is not dropped, as I assume the overall impact resistance and stability might be affected by leaving out those two screws. I'm guessing HP put them in there for a good reason, but if one is careful, not a bad idea to leave them out for future convenient access to the innards. I've seen some people cutting two holes into the label over the crews, but to me that would not be an acceptable solution.

BTW, where would you get a new back label? Guessing there must be people out there making reproductions. Any members here making those?

About the batteries, I am aware that the classics have a dual separate charger and power circuits coming from the wall adapter, plus the contact between the two positive (lower) contact pins so as to separate the battery while its charging. Still I like to leave any heat generated by the charging process away from the calculator, and one never knows if that even one of those modern NiMH cells might have a slight outgassing episode, even tough they are better behaved than NiCDs. But why risk it, so I think its best to play it safe with battery charging and always do it outside of the calculator.

Speaking of charger damage, its a shame how many Woodstocks have been damaged (unknowingly) by sellers on ebay that find them and just automatically plug in the charger to test them. Then the ACT gets zapped and display does funny things, or nothing at all, and it gets listed as untested for parts only. Quite often I would send them a message explaining how and why they damaged the calculator, in hopes that they wise up, and the next time they will not do the same thing and at least one more calculator that has been sitting quietly in a drawer for 30-40 years does not get instantly zapped, and manages to survive the "ebay experience". Almost all of the sellers usually thank me for the information. Although many HP2x have been brought back to life thanks to the excellent Panamatik ACT, including one of my own HP25's.

[calc-calcs]

(10-05-2020 01:33 PM)AndiGer Wrote:  I also have a 45 with a power switch that moves a little hard. If I press it slightly inward to switch on/off the calculator it moves smoothly. I never concerned about. Serial is 1349S5... Maybe it depends on the production series.

Mine is a 1509S02...

And yes, slightly pushing down on the switch seems to nicely relieve the added drag.

[rprosperi]

(10-05-2020 01:07 PM)burkhard Wrote:  The specific Lubriplate product I believe Bob is advocating is their DS-ES grease, which is a fairly specialty item, but easy to find online. Here's the link to it on the Lubriplate web site.
https://www.lubriplate.com/Consumer/Cons...name=DS-ES
I've used this myself in the manner he suggests on Classic series calculators and it works.

Thanks very much for the clarification burkhard, that is the exact product I have and use (I learned about it from Katie here, years ago) and I was not even aware of the other products. And btw, one tube is a supply for many lifetimes, so get the smallest one you can.

I also agree with the comments GreyUser made, as internal application is better and less messy, but if the owner doesn't want to open the 45, I think this is best if done carefully.

[calc-calcs]

Its sold for $5.93 at the manufacturer's website.

https://www.lubriplate.com/Products/Grea...5-OZ-TUBE/

Yet if you search for it on ebay the lowest price is $16.85 for the exact same size 1.75 oz tube. And they won't send to PO Boxes, clear indicative that they are damned drop shippers.

[rprosperi]

(10-05-2020 02:42 PM)calc-calcs Wrote:  ...Quite often I would send them a message explaining how and why they damaged the calculator, in hopes that they wise up, and the next time they will not do the same thing and at least one more calculator that has been sitting quietly in a drawer for 30-40 years does not get instantly zapped, and manages to survive the "ebay experience". Almost all of the sellers usually thank me for the information. Although many HP2x have been brought back to life thanks to the excellent Panamatik ACT, including one of my own HP25's.

Me too! I often send this exact kind of note when I see a Woodstock or Spice listed as "untested / for parts / as-is" and a power adapter is in the listing. Most sellers indeed have thanked me for the insight, and to make the point more clear I typically tell them to state in the new listing (if they ever find another) that the unit has NOT been plugged-in to avoid damage. Together we may save many vintage treasures for future owners. Good to know there are other folks out there trying to save these!

[ijabbott]

Would pressing down on the switch and blasting it with a squirt of canned "air" do any good? I was thinking it might dislodge some of the dust clogging the switch mechanism.

[Dave Frederickson]

(10-05-2020 09:29 PM)ijabbott Wrote:  Would pressing down on the switch and blasting it with a squirt of canned "air" do any good? I was thinking it might dislodge some of the dust clogging the switch mechanism.

Probably not. It's likely that the old grease has hardened and needs to be cleaned away with some solvent. Then a little Lubriplate ES-DS will have it switching like new.

[GreyUser]

Repro labels can be found on eBay. Sellers are listed in the parts thread in the articles section.

https://www.hpmuseum.org/forum/thread-10769.html

[Dave Frederickson]

(10-06-2020 05:19 PM)GreyUser Wrote:  Repro labels can be found on eBay. Sellers are listed in the parts thread in the articles section.

https://www.hpmuseum.org/forum/thread-10769.html

Be aware that while these are excellent labels, they are not exactly like the originals in that they're missing "Made in USA" or something.

The back labels can be replaced with a little work.
https://www.hpmuseum.org/forum/thread-46...l#pid41414

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