Hello everyone,
As some of you know, I have sold a few expanded HP48G calculators. What I would like to do is release the information I have on the upgrades, and in particular, on how to open the HP48 without causing it damage. Of course, I had already posted an earlier version with some photos, and it was in fact based on a method that already existed on hpcalc.org. However, the methods were not precise, so it was not too difficult to recognize the calculator as having been opened. Over time, I have improved upon the technique and am now able to open and close an HP48 in such a way that, and unless you know exactly what to look for, you will likely not be able to discern an unopened HP48 from an opened one. This improved method is well documented.
I have also written a memory upgrade guide that fixes a number of mistakes found in existing memory upgrade guides. There is also no known guide for memory upgrades using a single 512KB chip and using all of its memory banks. Nor is there a guide for upgrades of 1MB or larger. I have written instructions for these upgrades as well.
With this information, pretty much anyone can fix their own HP48 or make memory upgrades to it if they are willing to invest some time and patience.
So now to the problem...
When I sell my HP48 calculators, I do my best to disclose any and all pertinent information about the calculator, especially if it has been modified. However, I cannot speak for anyone else. And what I want to avoid is the situation where someone does a poor job fixing the problems of a unit and pass of his unit as a working unit, only to have an unknowing buyer purchase it and have it break down some short time later. I am trying to imply that the information I have will revolutionize the HP48 industry. However, up to this point, any information on servicing HP48 calculators can be best described as sparse.
At the same time, I like to share information as others can benefit from it.
So... any advice?