Musings and comments about our common interest
While taking a look to Eric Rechlin's hpcalc.org site, I have learned that there is a Valentin Albillo's articles and documents site within too.
Valentin Albillo was one of the original HP calculator users in Spain - together with Fernando del Rey. He wrote a lot of articles and quizzes on all kind of HP Calculators - from the early ones to the HP71. He even collaborated to write Spanish-speaking HP application books (for example, for the HP34c calculator.
If you are interested in something more than the hardware, you're doing yourself a disservice if you don't add Valntin Albillo's site to your favourites!
Some personal highlights:
But there are literally hundreds of them!
Eric Rechlin, of hpcalc.org fame, has created (with the help of many but mainly based on his own gigantic effort ) what can possibly be the biggest HP calculator related document site.
You can acces it in this URL:
You can filter by language, author, source, related model and free text. Well organized and including many new scans. The list of documents is in continuous expansion and lists more that 1180 pdfs.
I have checked the quality of some of them and it is magnificent! I am far from checking all of them, or even a sizeable part of them - but many of those I have tested have been OCR'd, so that you can look for specific text - what would not happen on manuals taken as image only (many of the manuals that I have been using in the past). The difference is huge - mainly when you are looking for something in particular.
I wish you enjoy your visit to Eric's site - and that you can find what you were looking for!
We are now designing an adaptor to put two AAA batteries in a Spice machine. The Spices were the HP32E, HP33E, HP33c, HP37E and the HP34C - the top of the series.
The Spice machines were designed as low cost compared with the HP65-HP67 series, and as replacement of the Woodstock series. In opinion of many HP experts, too many corners were cut to manufature them - several internal connections rely on pressure exerted by the screws that close the box - while in previous units the box screws did not have circuit integrity functions. Therefore, these machines have higher fatality rate than other models.
One of the issues that plague the HP Spice is the battery bay. The original rechargeable batteries wear down, but the problem for the replacement is that the normal AA size is 1-2 mm too long for the machine - and you break the machine in the medium term. Ignacio Sánchez suggested to design an adaptor that used two AAA batteries - where the size challenge does not exist.
(continuing with the story: after the Spice series, the lower range was inherited by the Voyager series - for many, the most perfect calculator design ever, with the HP12c and the HP15c as the main examples)
We have applied the same solution that we created for the lower posts to the upper posts: a grip that clips on the keyboard circuit, and strengthtens the grip with the introduction of the screws.
In the case of the upper posts there was a requirement to drill anyway - so it doesn't change the original procedure. But the piece has the same 3-petal grip that we use for the lower post:
The connection strengthtens when the screw is put in, since it makes pressure to the sides of the post and makes sure it doesn't move. We plan to put it in production already!!
During the last week I have tried to repair (or install CL circuits on calculators) many calculators: 17 of them, of all types and flavours!
Again, repair statistics are quite stable, but there is a jump between 1st and 2nd:
All in all, a good week where we have managed to repair 13 of the units, there are still 3 to go and one completely unserviceable! Some have already been sent to their lucky owners.
Now I have a pile of calculators to fix. Many of them have corrosion points in the circuits and -above all- in both sides of zebra connectors.
No matter how thick the corrosion layer is, our recommendation is to put some drops of Caig DeOxit 100% (although other formulations (5%) may work too) and let it act for a little while. Then you can remove the crust of corrosion with a flat small screwdriver. You will be surprised because most of the crust will go and you will see the yellow colour of the copper below!
There are some areas where the corrosion is more difficult to remove: the parts where the main current happens. The additional resistance that builds up with the initial corrosition creates some heat that burns the debris in the metal path and makes it much more difficult to remove. One of the main causes is the "dust" that comes from the disintegration of the fabric inside the vinyl cases.
(By the way: it is a good practice to wash the vinyl cases to remove the dust. Use normal soap and doit by hand)
This product barely leaves any residue, and although it is quite expensive lasts a lot (if you use it drop by drop).
This product is typically used in audiophile circles to improve the conductivity of the Hi-Fi connections. I discovered there but it can be used in any case the connection is not good. It is one of the products you feel proud to recommend, like in "you will thank me to bring this to your attention.
We have detailed with pictures in our book how to repair the most typical card reader repair: the "gummy wheel" problem. This appears when the original material that was used to move the card disintegrates into a gooey mess. This is covered both in the book but also on a number of other websites.
We have found also another type of damage: a similar disintegration in the material between the engine axis and the endless screw that transfers rotation to the wheel. It shows in the noise of the transprt (which is the endless screw skipping over the engine axis). This will appear in the next version of our book. It basically consists on:
I will include pictures once I have done another fix.
Some interesting units arriving! Some will need repair, but altogether very interesting details! a family picture:
We have been using for already a couple of years our lower post repair piece. It is designed to replace both lower posts of the HP41c, since these are often broken in the full-nut HP41c clculator, and which are key for the calculator work since they hold in place and under pressure the nut processor circuit. The idea for the part was to have a single piece for both posts - the attachment on one side provides torque resistence for the other side and vice-versa.
This has been quite a success but it requires good alignment of the piece with the original holes, and it depends heavily on the glue quality. If the pulling force was too strong, we risked to have the piece off the keyboard circuit. This is despite having given a wide gluing area.
We have created a new low post repair part that requires some drilling of the rest of the original post, and introducing "claws" inside the hole. The piece is designed so that when the screw enters in, it pushes the 3 "petals" of the claw to clip below the keyboard circuit - making it much less dependent on the glue!. It is really strong - the longer the screw the stronger it is. Definitely an advancement over the previous method. What you lose having to drill deeper the original posts, you gain ensuring a perfect alignment, and a much better resistance to pulling forces.
Here are some pictures of the piece (sorry for the bad lightning conditions!) and 3D-renderings too: