To clean - or not to clean ... ?

[ThomasF]

Hi,

I recently managed to buy a classic HP35.

I knew from the ad that it was an old one (1143A....) and with a frontplate without the "35" – so probably from the second production version since no red dot.
When I got it (with original case, manual and charger, even the (un-posted) service-card dated "1972-10-12" was still there), I realized it was quite a pristine device. As far as I can see, the device has never been opened (the backpanel seems to be the original one (“Made in” etc. is on the small label between the bottom feet) without any bent corners). All visible screws are "white" compared to “black” ones on newer models.

It even has the 2.02 bug

There is some silvery color missing on the frame above the switch but no scratches and even the rubber feet looks fine. But since it has probably been in an office for many years (and probably forgotten in a drawer since then - luckily without battery!) it is a bit dirty.

So, what would your advice be? Should I disassemble the unit and clean it, or leave it as it is? I’m eager to get it cleaned – but I know that even how careful I am – the backplate will probably not be the same again.

It is working perfectly - all keys, display and the switch, and I intend to keep it in my collection, but curious how you would have done.

Cheers,
Thomas

[isanchez]

Hi,

Congrats for the finding! It is really a remarkable calculator.

I collect these calculators and I have a large amount of them.
In my opinion: Do not open it, if not necessary, which is like saying: if it works fine, do not open it, moreover if it is necessary to break or put in (serious) risk aestethical aspects, which is the case.

I would distinguish between external cleaning and external restoring. I like to keep clean the calculators (some people talk about keeping the "patina", I talk about removing the dirtiness) and only in some cases, restoring. I.e. there is a big debate about restoring the silver lines in HP35 or not...this is a personal decision. ;-D

Enjoy your HP35!

Kind regards

Ignacio

[ThomasF]

(03-18-2021 08:10 AM)isanchez Wrote:  Hi,

Congrats for the finding! It is really a remarkable calculator.

I collect these calculators and I have a large amount of them.
In my opinion: Do not open it, if not necessary, which is like saying: if it works fine, do not open it, moreover if it is necessary to break or put in (serious) risk aestethical aspects, which is the case.

I would distinguish between external cleaning and external restoring. I like to keep clean the calculators (some people talk about keeping the "patina", I talk about removing the dirtiness) and only in some cases, restoring. I.e. there is a big debate about restoring the silver lines in HP35 or not...this is a personal decision. ;-D

Enjoy your HP35!

Kind regards

Ignacio

Thanks Ignacio!

Yes, that is probably a wise/safe way to go. I will carefully clean the external, there are dirt etc on top of the keys and on the overlay, as well on the body itself, but I will refrain from opening the device.

I have no plans to try and "restore" it, I think it is ok to look used - gives some history to the device (after all it is almost 50 years old now!), but the "filth" could be removed - so it looks like someone takes good care of it.

As with all my calcs, it should be nice to have in your hand and should be used every now and then - not just being locked away!

Cheers,
Thomas

[aurelio]

Hi Thomas and congrat for you "new" calculator!!
I'm actually agree with Ignazio but I don't understand why you need to disassemble the unit to clean it, is it so deeply dirty?
is it possible to share with us at least a pic ?
About the silvery color missing on the frame, as Ignazio said, there are different opinions.
Personally I think that to restore is quite easy only with the third series, after removing all the original silver from the bar.
Even if you have to retouch a small dot on the previous models, it is more difficult, cause the colour, usually, you do it with a chrome marker pen, never matches perfectly the original one and sometimes the remedy could be worst than the desease....
For this reason I'm agree with the people that remove completely the "survived" silver, in those cases, leaving the frame completely black....



Cheers,
Aurelio

[ThomasF]

(03-18-2021 11:29 AM)aurelio Wrote:  Hi Thomas and congrat for you "new" calculator!!
I'm actually agree with Ignazio but I don't understand why you need to disassemble the unit to clean it, is it so deeply dirty?
is it possible to share with us at least a pic ?

Hi Aurelio!

Thanks for your comment!

Haha, no - it is not "that" dirty! But I have seen some people disassemble and clean e.g. all keys etc, and it was that that was on my mind when I saw the calculator.

I'll try and add a picture - but I guess it is hard to get a correct picture. Most noticable is the side of the calculator, but also the sides of the keys (I have cleaned the top of the keys a bit).

Best regards,
Thomas

[aurelio]

Ok Thomas and thank-you for the pics, what a beauty!!!
For the keyes I suggest to clean them with water and soap: soak a cotton bud with the mix and clean all around them, holding the calculator upside, to avoid drops inside.
For the frame leave it "as is", if you like, you can print a Dymo label ('70 style )with HP35 v2 2.02 BUG and cover the left side of the frame.

Here, in Italy we say "eye does not see heart does not hurt", you will love it anyhow

[[kby]]

is this a US model? I don’t think I’ve seen a charger that looks like that before.-kby

(03-18-2021 12:07 PM)ThomasF Wrote:  

(03-18-2021 11:29 AM)aurelio Wrote:  Hi Thomas and congrat for you "new" calculator!!
I'm actually agree with Ignazio but I don't understand why you need to disassemble the unit to clean it, is it so deeply dirty?
is it possible to share with us at least a pic ?

Hi Aurelio!

Thanks for your comment!

Haha, no - it is not "that" dirty! But I have seen some people disassemble and clean e.g. all keys etc, and it was that that was on my mind when I saw the calculator.

I'll try and add a picture - but I guess it is hard to get a correct picture. Most noticable is the side of the calculator, but also the sides of the keys (I have cleaned the top of the keys a bit).

Best regards,
Thomas

[CY-CL]

This is a very early German-Swiss Charger… 00035 – 70001. They were here delivered (Germany and Switzerland) sometimes with a Red Dot Hard Case.

The great finding is the Charger!!! Congratulation!

[ThomasF]

(03-18-2021 06:17 PM)[kby] Wrote:  is this a US model? I don’t think I’ve seen a charger that looks like that before.-kby

Hi!

Funny you noticed that!
I was working with selling and repairing calculators between 1982-1994 and I had never seen one of those either, first I thought it was a home-made thing.
But no, it is a original HP charger for Europe, model nr 00035-70001 (110/220V).
So, apparently also sold in the Nordic countries.

   

Cheers,
Thomas

[HP67]

I am squeamish so I clean any used item I buy very thoroughly. I can recommend the Simple Green brand cleaner for external cleaning.

I am very impressed with this chemical. I buy it in concentrate and dilute it around 1:10 in a spray bottle.

What is impressive to me is that it cleans thoroughly, and yet it does not remove labeling, markings etc.

I had some amazing luck with a local product cleaning HP 48s. It was also germicidal. But I don't have it here. I used Simple Green on several HP 41 models with no damage.

[hpchris]

Very nice!