48g over-zealous cleaning

[robjordan]

A word of advice. Take care cleaning your HP 48 with isopropyl alcohol.

I found not one, but two 48Gs at the back of a drawer in my parents' house. I'd already acquired a bunch of my late dad's collection as I've written elsewhere. One of them is from 1996 and pristine, another was from 1993 and quite dirty. I gave it a good clean with IPA and it came up looking very nice... except for the letters A to F, which had disappeared. Evidently much less firmly printed than the legends on the main keyboard below.

Shame. :-(

Rob

[Jeff_Birt]

Alcohol is good for removing sticky residue and flux but not my first choice for general cleaning of cases and keys. Alcohol will also fade/dissolve the silver paint many vintage computers are covered in.

For cases and keys, a mild cleanser like Formula 409, or dish soap and water, it a safer choice. It will get rid of dirt and grime but will not dissolve paint.

On the other hand, if you want to loosen paint and not harm plastic than DOT 3 brake fluid is your friend. Soak the plastic in and in a few hours or days the paint will peel right off.

[John Keith]

(06-08-2023 04:22 PM)Jeff_Birt Wrote:  On the other hand, if you want to loosen paint and not harm plastic than DOT 3 brake fluid is your friend. Soak the plastic in and in a few hours or days the paint will peel right off.

Actually some plastics can be harmed by brake fluid. As always, the adage "try in an inconspicuous area first" applies.

[robjordan]

> Alcohol is good for removing sticky residue and flux but not my first choice for general cleaning of cases and keys.

You live and learn! Hands up to my own foolishness. IPA has the nice property that it evaporates cleanly, and it hasn't damaged any other part of the keyboard, which is why I called attention to the relative fragility of the top row of letter legends.

Rob

[olivil]

I've had great luck with naphta (lighter fluid)!

[John Garza (3665)]

Completely disassemble and put case and keys into ultrasonic cleaner with Johnson's liquid baby shampoo and fabric softener (to reduce surface tension)

When dry lightly wipe with damp (not wet!) gun oil cloth to restore the luster to the plastic.

-J

[gwh]

I've also used glasses cleaner sprayed on a tissue with good results and no harm.

[vaklaff]

(06-09-2023 05:27 AM)gwh Wrote:  I've also used glasses cleaner sprayed on a tissue with good results and no harm.

Same here. I read this advice somewhere here in the forum and have been using it since then with success.

(06-08-2023 05:02 PM)John Garza (3665) Wrote:  When dry lightly wipe with damp (not wet!) gun oil cloth to restore the luster to the plastic.

Interesting! Is there a reason for using gun oil specifically? And any specific property or component to look for or avoid?

[John Garza (3665)]

I've also used glasses cleaner (and windex) but disassembly and ultrasonic bath ensures all nooks and crannies are cleaned - a simple wipedown with anything won't accomplish that.

On the gun oil, I just happen to have it handy. In comes in needle applicators for pinpoint application, that's why I like it. But I have used a light spray of WD-40 on a cloth, then wipe the calculator. The goal is not to wet the machine and make it slippery - that's too much. It's that cleaning will reduce the plastic luster - and a light application of oil will restore it.

-J

[John Garza (3665)]

Ultrasonic bath, polished/waxed display, repainted silver trim lines, and oil wipedown will make the machine look like new again.

-J

[robve]

IPA can accidentally spread and flow into cracks and other spaces where you don't want it.

To remove stubborn stickiness from bare plastic or metal, I use hand sanitizer gel with 60%-70% alcohol instead of IPA, because it is a lot easier to locally apply on small spots and to wipe excess off. It works well with q-tips too. Great way to remove ball pen paint and other streaks from plastic without using heavy-duty stuff. Then wipe the surface clean afterwards with microfiber cloth. I never had any damage from using this method.

Higher quality electronic wipes appear to work OK to remove surface fingerprints and modest grime. Be extra careful with surface-printed lettering etc.

Plastic cleaner, such as Novus 7020, works well to clean plastic surfaces and is generally safe.

Do not use Windex, because it can strip paint and damage surfaces (e.g. it can even damage car clear coats and paint). Only use Windex on plain plastic surfaces. I only used Windex once to clean a dirty plastic keyboard frame that had no lettering.

To clean leather and soft vinyl calculator cases and protective covers, I use Leatherique Prestine Clean. It is very gentle on leather and vinyl, yet cleans surprisingly well. Experienced vintage car restorers use it for a reason.

- Rob

EDIT: mention plastic cleaner and warn about Windex. RE-EDIT: mention Leatherique.

[teenix]

Be careful cleaning the battery wells of Classics too, the black serial number printing comes off the sticker quite easily.

cheers

Tony

[John Garza (3665)]

Ajax and Brillo pads....

La da dee...(scrub scrub) I'll get this thing clean or else! ...La da dee....

[Allen]

I've had good luck with "slightly damp" long-pile wash rag or towel.
Lay it on a flat surface and turn the calculator face down and gently rub the calculator on the towel in a circular motion.

From time to time I need a Q-tip (TM) or similar cotton swap with only a little water or diluted alcohol to clean in between the keys. But this should be done with care, as the OP suggests!!

[Jeff_Birt]

I ran into the alcohol issue on a TRS-80 PC-2 printer/cassette interface today (Sharp CE-150). The TRS-80 version is painted flat black. I wiped it down with Formula 409 but there were a few stubborn spots. Not being sure if it was sticky goo or the result of the NiCad battery out gassing. I tried a quick wipe with alcohol on the back, a.k.a. an inconspicuous area, but it was also removing the flat black paint. It was not sticky goo but from the corroding battery pack. At least the PCB and innards were unscathed.

[HP67]

I find Simple Green (the colorless variant) does a great job on all kinds of electronic device housings while being very gentle.

I use it on hifi gear, HP calculators, etc. and have never had a problem. I buy the straight Simple Green (undiluted) from a local distributor and cut it 4/1 with tap water (or distilled, depending on application). Sprayed on a microfiber rag and applied to HP keyboards with the device upside down, it cleans very well and does not seem to leave any residue.

[John Keith]

Simple Green is really useful but it contains the same ingredient as Windex (2-Butoxyethanol) in even higher concentration. Be careful with it on painted surfaces.

[robve]

On a related note, I should add that to clean leather and vinyl calculator cases and protective covers, I use Leatherique Prestine Clean. It is very gentle on leather and soft vinyl, yet cleans surprisingly well. Experienced vintage car restorers use it for a reason and that's how I came to discover it and use it.

- Rob

Correction: it's "Prestine" Clean, not "Pristine" Clean, oooooh marketing guys going nuts with words.

[HP67]

(06-11-2023 06:46 PM)John Keith Wrote:  Simple Green is really useful but it contains the same ingredient as Windex (2-Butoxyethanol) in even higher concentration. Be careful with it on painted surfaces.

Thank you, I did not know that.

Anyway I have used it quite a lot and it has earned fame for me by never damaging anything.

I wonder if perhaps the European formulation does not contain that, or, the fact I dilute it 4/1 with water reduces the concentration to non-damaging levels, or something else.