HP-65 1508A04995 restoration and ideas to share

[albertofenini]

Hello everyone

we have started to restore an HP-65, and I'm attaching few pictures
Nothing on the cosmetic side, we have worked more on the functionality side

we wanted however share two things and ask the forum about a curiosity

inside the unit there were two labels, a bigger one that was loose inside the unit
and a smaller one attached to the card reader unit

it appears the unit was repaired in the 84, and we were curios to know if the
codes on the label can be translated in the equivalent repair work performed,
any idea ?

we basically have only cleaned the unit and rebuilt the gummy wheel

while doing so we have dropped a drop of the spray lubricant that we have
pictured (@Administrators we are not whatsoever related to this product and/or
its sale, if this is not convenient please let us know and we will remove the picture)

this particular product is way better than what we used before (the WD-40) as it
is "dry" and has made very very quiet the motor, so we wanted. to suggested

also, we have found useful to mark with the tip of pen (red in this case) the
position of the pin that keeps the gummy wheel attached to the card reader unit,
a correspondent mark has to be done on the card reader

we believe it can make easier the alignment procedure

also, after the answers we had got about the correct size for the o-ring
we had purchased a silicon tube ID 1/8" OD 1/4" which in metrics sets the
OD at the value of : 6,35 mm

this more or less the equivalent OD of a 006 o-ring which has an ID of 2,90 mm and thickness
of 1,78 mm OD = 2,9+1,78+1,78 = 6,46 mm

In the pictures you will notice the tubing cut and mounted on the wheel

However, even with a drop of glue, the ID is slightly too big for the wheel
and it slips without transporting correctly the card

We went back to the o-ring (pictures will be updated soon) and it worked fine

As anyone ever used the tubing approach and has experienced a similar problem ?

Will keep posting, next works to be done is to clean the keyboard plate as
the upper row is working intermittently and change we "clutch"

Also one of the pins for connecting the external charger is missing and has been
replaced with what looks like a needle to ensure the contact necessary for running
on battery

Take care and thanks for any idea you will want to share !

Pictures can be found here : HP-65 1508A04995

[albertofenini]

Update

Added photos for the o-ring, the cleaning of the keyboard pcb, the polish of the display and the matte finishing for the faceplate

Still missing the “clutch”

Hope it can be of help for someone

Take care !!!

Pictures can be found here : HP-65 1508A04995

[Mike S]

Thank you Alberto for your, as always, excellent 65 photos and notes.

Sorry, I can't shed light on you labels question. Could you though, tell us how you polished the calculator display window?

Quote:Added photos for the o-ring, the cleaning of the keyboard pcb, the polish of the display and the matte finishing for the faceplate

Mike

[albertofenini]

(06-11-2024 02:14 AM)Mike S Wrote:  Thank you Alberto for your, as always, excellent 65 photos and notes.

Sorry, I can't shed light on you labels question. Could you though, tell us how you polished the calculator display window?

Quote:Added photos for the o-ring, the cleaning of the keyboard pcb, the polish of the display and the matte finishing for the faceplate

Mike

Sure we can, but first two things must be said :

@Administrators : once again, we are not affiliate with any of these vendors ad if the post is not appropriate please remove it
or notify us and we will remove the pictures showing commercial products

Try these at your own risk, we do not take any responsibility for whatsoever damage
can these products cause to your devices

That said :

PLASTIC SHELL (mostly the lower half)

"Mafra All Purpose Cleaner" comes from the world of car detail (that's another passion we have), it can be diluted 1 part of product 5 parts of water, usually used
for cleaning plastics from the interior of the car, and it works quite well on the external shell of the calcs, we have NOT used on the front place as it could permanently damage the lettering

Should you not be able to find Mafra products, any products from car detail for interior plastics should do, we have found these much less aggressive then the degreaser found at the supermarket we used before

After that, only on the lower shell, we apply some "Pronto", is a liquid wax usually used for wood forniture, apply a couple of drops and with some cotton distribute,
it will give a nice and pleasant finish, remove the excess and let dry, it is not oily
which is what we like

DISPLAY

"Sidol" is an almost liquid polishing cream, usually used for polishing silver or metals we had excellent results with the display
Just apply a drop of two, distribute with a cotton and let it dry

Then we use a Dremel accessory 423S at the minimum possible speed (5000 rpm on our unit) as you do not want to overheat and ruin the display

Depending on how deep are the scratches you may want to use some sandpaper first
start with something like a 600, possibly with water, and then go up to step by step up to a 2000 always
with water

Then apply the cream polish process and it will look like new

Remember to protect very well the surrounding silver trim or it will worn out

We like, to leave some age signs, it must look restored but not made like off the shelf,
but that it's just us you can obviously do it as you like it more

FACEPLATE

For the front place use a drop of very very light soap and warm water, do not use hard brushes or similar things or you'll ruin it for good, rinse and repeat

After the dirt has been removed, and after you have masked and protected the trim and the display you can apply few layers
(we do it five times but we let the faceplate dry in between) of "Tamiya TS80", it will give a matte look very very nice

For these and many others tips credits must be given to a lot of other authors here in the forum from whom we have learned reading their beautiful posts,
list would be too long to name them all but we will be for ever thankful as their support is unbelievable

Hope this help, take care

Updated pictures can be found here : HP-65 1508A04995

[Mike S]

Appreciated your helpful reply on cosmetic repairs to calculators.

I note you mentioned using sandpaper possibly dampened. I often use what I term, 'wet and dry' paper (on the back it says 'waterproof silicon carbide abrasive paper').
This lasts much better after wetting than sandpaper.
600 paper seems pretty rough to use on a calculator's plastic window.
You'd need pretty deep scratches to justify that I'd have thought.

I will (very gently) try your idea of using a silver/metal polish on the screen of my 49g+.
I read someone's observation that the 49g+ screen could be scratched just by looking at it!
Mine has fine scratches on its inside surface that I think were worsened when I used a watery toothpaste to treat it.
Newer calculator screens are surely not as tough as the classics'.

[teenix]

I wonder if those car headlight plastic lens restoration kits would do the job.

cheers

Tony

[albertofenini]

(06-14-2024 03:54 AM)teenix Wrote:  I wonder if those car headlight plastic lens restoration kits would do the job.

cheers

Tony

Hi Tony, good to hear from you

It may, but the two thicknesses of the plexiglass are totally different
also the headlights are finished with some transparent lacquer, but it
would be worth a try

I do have a few units that will totally need your advise, but I'll post them separately

take care !

[John Garza (3665)]

For display scratches, I've had good results with Novus 2. For extreme cases Novus 1 followed by Novus 2. And a coating of 'Future Wax' as a last resort will fill all scratches and leave a smooth finish. Though it's difficult to find these days.

-J

[JohnRausch]

Wenol polish works perfectly on the screen. Red is more aggressive the blue, but both work well.