HP15c CE including Overlay 16c, Firmware change and Programming cable to avoid the DEC bug in HP16c feature, and change debouncing time from 80ms to 100ms to avoid double keys

Includes:

• HP15c Collectors Edition
• Overlay 16c for the NOMAS 16c feature
• Patching firmware to avoid the DEC bug in NOMAS 16c feature
• 100ms debouncing time
• Programming Cable

Overview

The HP 15C was a very popular RPN calculator from the 1980s (1982-1989) that, despite the last units rolling off the line over 30 years ago, is still highly sought after by collectors and users. After a long wait, the HP 15C is now being temporarily re-released as a Collectors Edition.

This special Collectors Edition comes in a nice storage box, including a printed manual like the one from 1984 with a foreword on the history of HP's calculators, written by Włodek Mier-Jędrzejowicz and Gene Wright.

Enhanced version of the classic HP 15c

After a 12-year hiatus, HP is reintroducing the popular HP 15c Scientific Calculator. This HP classic features a unique “Collector’s Edition” script, making it a great gift for collectors and engineers alike. The 15c offers users a high-end and portable, scientific calculator with programmable functions and built-in support for complex numbers, matrix math, numerical integration, and root solving, which makes this device one of the most capable calculators HP has ever made.

Intelligent design, powerful processing

The Collector’s Edition HP 15c maintains the same intelligent design as the original but touts up to 100x faster processing speed. Its compact size and lightweight metal frame allows users to conveniently carry the HP 15c from meeting to meeting. Unlike other scientific calculators, the HP 15c also offers an intuitive, horizontal interface, just like the original.

Rich set of advanced scientific features with more memory

The HP 15c is a powerful problem solver. Programming capabilities include conditional and unconditional branching, subroutines, flags, and editing. Plus, users can program up to 672 steps of calculations for rapid retrieval (increased from 448). The new 15c also offers Direct and indirect storage in up to 99 registers (increased from 67). This handy calculator operates using Reverse Polish Notation (RPN), reducing the number of keystrokes to complete your calculations.

There is 5% discount for 5 units or more, 10% discount for 10 units or more.

The overlay is NOT a HP product. It is used with non-manufacturer-supported features of the HP15c CE calculator. HP and its licensees are not responsible for its use and suitability for any application, and will not give support on its use - go instead to user webs like hpmuseum.org. The overlay is intended just for exploration of the calculator features, and it is designed and produced by The Calculator Store SLNE. There are known bugs in the HP16c mode.

IMPORTANT NOTE: The production units do not have protective plastic on the calculator surfaces, as shown in the video. This was only done on the 5 test units sent to us

New, true leather case for HP Pioneer calculators, including HP17bII, HP10b, HP14b, HP27s, HP22s, HP32s, HP42s calculators. Dark brown color like the original.

The original Pioneer calculators had a vinyl case that resisted quite well the passage of time - and that was designed to be kept in the jacket pocket. It also had the knitting "inwards" so that it occupied the less possible space for a given volume.

Later versions (HP17bII+) have been made in false leather (called PE), which has a very low resistence to external scratches. There are several types but all of them in my possession have now a very bad aspect after few years. For the current HP17bII+, the case is not even suited for jacket pocket, since it has very square corners.

We have decided to create real leather cases that stand the passage of time, made with the same material that pocked cardholders and money holders are made. We have selected a manufacturer in Ubrique (Spain), famous for this kind of work. We sent to them the originals and the calculators that go with it, so that the case you have with you is not something similar that fits well - it has been expressly designed for your calculator

Please take a look also to the leather cases for Voyager (HP12c y HP15c).

Assembled Battery-back port module repair kit for the often damaged flexible PCB in the battery bay (and I/O ports) of the HP-41c range of calculators.

This is the FLAT version, when the screw head domes are broken and grinded down - see pictures.

It is made of a flexible circuit, already collated to an 3D-printed battery-expansion ports module, ready for assembly within your HP41c. Standard colour of the base is black, but it can also be ordered in white (like the pictures)

Instructions for battery and ports module

Open the calculator

First remove the rubber feet. To do so, use a small, flat screwdriver and introduce it beneath the rubber, taking care of pulling also the adhesive sheet that glues the rubber to the calculator. Try to make here a good job because usually you will have to reuse the rubber feet when you're done. Put the rubber feet aside so that they don't hinder the work (they have an uncanny ability to adhere to shirts, tools, calculators and eventually get lost.

Unscrew carefully and slowly the four screws beneath the rubber feet. Turn gently the screws: they operate on plastic that, after 30 years, is very brittle and fragile. It is very easy to break a screw post or "overdo" the thread.

Remove the back side of the calculator and put it aside. For comfort, remove also the intermediate piece between backside and main body. Later we will take care of putting it the right way, since it has two ways.

Remove the old piece

Now it is the time to remove the damaged battery-ports module. To do that, first remove all 4 module covers or modules; then pull the module vertically and carefully, since there are four plastic tabs in the calculator used to secure it, and it you do horizontal movements you can bend or break them. Yes, they have also became brittle!

Sometimes grit and grease have "glued" the old piece to the backside. It will be very difficult to remove it. Be aware that it is NOT glued by design - this is an unwanted effect of grease, grit and time. To remove the piece in this case, try pushing up with a screwdriver on the back module connectors. Increase upward force until eventually it separates from the body. Clean the backside plastic with water and soap or a lenses cleaner. It may happen that one or both of the screw supports are broken. You will have to repair it beforehand with the broken back repair piece.

We assume that the screw supports are broken. Grind down to flat the screw supports with a dremel-like machine with some grinder head.

Once the backside is clean and free, glue the lower side of tthe module with E6000 glue, including putting some in the holes where the tabs are going to be. Then insert the module carefully, making sure that the 4 vertical tabs are not bent. This is done without the module covers in. Be sure that it goes down to the calculator body, and put pressure on the sides with cloth pegs to ensure good contact. Put also the module in to ensure good vertical position. Leave it overnight.

Reassembling

You can now reassemble the calculator. Put the keyboard face down on the table. Then, put the intermediate piece with the open side upwards, taking care that the wider part is up, like "opening up"  (this piece has a slight angle when looked from the front of the open side). This is important for the calculator to close properly. See picture.

Then put the back side on top. You can start by any screw - I usually start by the upper ones. If everything is ok, you will be able to screw through the piece and into the calculator. Screw carefully not to break the threads. If that happens, repair will be substantially more complex and will need the upper post repair piece and some drilling.

And that's it!!

Please be sure to eliminate rusting from the main board with Caig DeOxit (best), WD-40 (not as good) or other suitable cleaner, applied with cotton buds.

Save your HP41c !!

Sponge for the standard HP41c vinyl case. The original cases were designed to carry the calculator and card reader together. However, as these were sold separately, the case was too big for the calculator alone. HP supplied the case with a sponge within the lower part of the case to act as padding. These sponges may have been lost or deteriorated over time, so we have made a replacement with the right dimensions.

New, true leather case for HP Voyager calculators, including HP12c, HP12c Platinum, HP10c, HP11c, HP15c, HP16c calculators.

Note: this is not an original HP product.

The original Voyager calculators had a vinyl case that resisted quite well the passage of time - and that was designed to be kept in the jacket pocket. It also had the knitting "inwards so that it occupied the less possible space for a given volume.

Later versions (including anniversary units) have been made in false leather (called PE), which has a very low resistence to external scratches. There are several types but all of them in my possession have now a very bad aspect. For the current HP12c Platinum, the case is not even suited for jacket pocket, since it has very square corners

We have decided to create real leather cases that stand the passage of time, made with the same material that pocked cardholders and money holders are made. We have selected a manufacturer in Ubrique (Spain), famous for this kind of work. We sent to them the originals and the calculators that go with it, so that the case you have with you is not something similar that fits well - it has been expressly designed for your calculator

Please take a look also to the leather cases for Pioneer (HP17bII and HP42s types) and HP41c cases.

The HP-41C series are programmable, expandable, continuous memory handheld RPN calculators made by Hewlett-Packard from 1979 to 1990. The original model, HP-41C, was the first of its kind to offer alphanumeric display capabilities.

HP41c Tall Keys, perfectly working, with all port covers and no traces of rusting. The serial number is 1944A (meaning it is from 1979) and this unit has the metal keyboard plate instead of textured plastic.

The machine comes with original vinyl case.

Lower Post repair

Material needed

• Lower post repair piece
• Clothes' peg
• Keyboard support for clothes' pegs

Let's assume that both posts are broken or cracked. The effect of this cracking is that the screws do not do their job. Usually, using longer screws may help, but this typically is short lived since the cracks will continue downwards. Once the pressure between both halves is softened, the calculator doesn't work anymore. The solution is to repair the broken posts. 

Old methods to repair broken post is to glue them (but this doesn't hold together too long) and to tie them down with very small gauge copper cable, applying pressure so that it holds together. This may solve some cases, but not when the screw path has been destroyed - maybe due to strong tightening of the screws.

Other repair methods have been proposed, including drilling down the screw and placing in its place a cylinder with screw path, glued in place. We tried this method but there was a problem: the torque used to screw resulted in cracked glue and the cylinder separating from the substrate - every time.

Our method was devised with three goals in mind:

1. Try to avoid the torque from the screw forcing on the glue with the substrate
2. Try to ensure that the front part of the calculator is pulled up when screwing the back side on.
3. Try to be compatible with all known zebra connectors - including our own.

The piece that we have designed requires drilling the old posts to the keyboard ciruit level, taking care of leaving the hole clear. The design on the piece is such that the pin will be glued to the inner part of the rest of the screw post; and the surface of the piece can be glued to the keyboard circuit, so that the torque on the substrate is avoided (it also helps that torque is also resisted by the other post, when using the full piece)

When gluing the piece, there are several precautions that need to be taken:

• Be sure of covering the zebra circuit part with tape -we don't want the glue to cover it.
• Cover also all nearby pin holes of the keyboard. If glue comes into one such hole, the key will not register. In severe cases, the key will be down all the time, glued in place!
• When applying pressure, use clothes' pegs to hold the piece in place, preferably on the outer side.
• To avoid pushing the keyboard down, and only push down the front of the calculator, use the keyboard cover we have designed to support the pegs. Pushing the keyboard instead will result on separation between both halves of the calculator, since the attachment of the substrate to the pin will be at a lower level (the keyboard is linked to the keyboard circuit, not to the substrate)
• Use epoxy glue, type Araldit. 
• Let it cure overnight.
• Remove the tape over the zebra circuit paths.
• Place the zebra connectors
• Assemble the calculator and test.

We recommend to repair both posts at the same time. However, if you are confident on the resistence of the other post, you can use our 1-side piece. As it is symmetrical, it can be used for both posts, just twisting it 180º. Using the full piece, the other post side does not need to be glued - the torque resistence is done by the post itself over a much longer distance.

Alternatively, you can cut the other side of the 2 post piece with a tweezer and glue in place the rest of the piece.

HP41c back port cover - 3D printed by the new HP method - which renders a much better surface quality than typical nylon. Still not identical to the original (this one is blacker) but dimensionally and functionally equivalent.