Musings and comments about our common interest
I have now an old HP41c where the upper circuit is pressed down to the zebra connectors via nuts. Now, it is difficult to ensure an even pressure and I am having problems with some of the digits. But if we force the nuts, I may break the post - as it has happened in other cases. These are the situations our new piece (wait until we can put it on sale) is made for.
This piece is intended to be put on the lower posts (where it fits tight to aid in case of cracked posts) and gives the necessary mm. of thickness so that the back side of the original type can pass the pressure on the circuit so that it stands firm on the zebra connectors. This negates the use of nuts, which can be changed only a couple of times, lest they break the thread of the post (or the post directly, as it has happened to me a couple of times). I am testing different thicknesses to find which will be the final product.
Say goodbye to the nuts!
We have now prepared a couple of new products designed to solve more HP41CL repair problems. We will discuss today the first one.
Our bent to do c to CL conversions has led us to specialize on full nut repair, instead of half nuts. But some of the tools and methods are also valuable for half nuts too!
The first of the new items we have created is the adaptor to replace screwed nuts in the original HP41C. You may have seen one of this: the processor circuit is secured to the main board with metal nuts around the lower screw posts. The problem with these: it is very easy to destroy the thread, since he read was formed by the action of the nut on the first attachment, nearly 40 years ago!
In the later units, the processor was secured in place by the pressure of the back side through two cylinders collated to the case. If you have one of the old cases, and you have broken the nut thread, you need to find a solution to push the circuit down against the zebra connectors. This is such solution.
We have created a nylon piece that fits tightly around the lower screw posts, with a small bezel to ease the port entrance, and occasionally making a broken post able again. This piece translates the pressure from the back side of the calculator down to the circuit. Don't need to find the right height, or to adjust the angle: it will work - every time.
The piece has sides! As the back side has an angle compared with the circuit surface, we needed to create this angle to the piece. Therefore it can only be put one way.
As the color here really doesn't matter, we have created the price in the cheapest, clearest color from 3D printing: white.
I hope that is piece helps some of you fixing your beloved calculator!
I am receiving many request to repair Clamshell (28c, 19bII, 18b) or Pioneer-type (42s, 17bII, 32s and many more calculators). Opposite to the previous models, these were built NOT to be repaired. The parts or the body are thermo-soldered, and opening them means typically breaking these bonds - which are quite difficult to repair in an aesthetically correct way.
There are some websites that talk about this. Most notably you can see repairs for a HP17bII here:
And here also (about a HP42)
I have finished the current batch of 41CL from Systemyde. Time to reorder. Please show your interest if you would like to buy one. If not, it’ll take longer to receive the board. I am only purchasing as many boards as interest shown from customers. I will order another one this time since the damned loss of my calculator during the latest business trip. Every time I think about it, it drives me mad.
It seems that many people are attracted to this calculator, but they do not dare to assemble theirs. On one side, they may have an old HP41c laying around, but for personal reasons, they want to keep it as is; on the other hand, to spend over 100€ in a bet in Ebay (where you can end up with a non functioning calculator, or one with deficient aesthetics) is a risky proposition. And they do not feel comfortable opening their calculator to do it.
While I am very satisfied by doing this work, I would not like European calculator amateurs to be put off to buy from us to get this wonderful calculator. I encourage them to try by themselves. If they fail, they always have professional repairers that can finish off their job properly.
Just a couple of hints to a successful HP41CL conversion.
- The contacts between the battery module and the circuit itself (on both sides)
- The contacts in the ports
Once you have assembled your own CL, you will enjoy a sense of achievement (even though it was so easy), and admiration on how can a 30 years old machine be so well designed. As well, you will feel grateful to Monte Dalrymple and his outstanding achievement.
But if you still do not dare to do it, even after the above, please contact us at email@example.com for quotes and pictures of the donor calculators. We’re more than happy to help!!! As well, we’re willing to buy your malfunctioning full nut HP41c or cv.
Now I am looking for a way to produce overlays for all the software we now have in a convenient way.
Last but not least: software. I do not know what you will fill your CL with; but I draw the Library #4 software suite from Angel Martín, including the PowerCL, Sandmath 44, advanced matrix #4, OS additions and others. Programmed mostly in Mcode, these change your calculator to a very different animal.
PS: Gardermoen airport has informed me that they have found the HP15c LE that I have lost the past week. Not all is lost! However, I had already opened another one, so I will give it to one of my children.