Hi, Steen;
there are two "EXTERNAL" differences between the soldered and solderless Spice (all HP3x-series) types: the weight and the keys "movement amplitude" (I cannot remember a word for this... Sorry!). Unfortunately you'd better having two units so you could compare.
Solderless models are heavier because they have a metal plate inside to keep structural "linearity" and integrity. Now that I'm mentioning this fact, it woobe a good idea to simply measure both weights... ;) If there is a non-destructive way to check for metal parts (metal detectors?), maybe this would also be useful. As a brief comparison, if measuring with your own hands, solderless units without batteries are about the same weight as soldered IC's units WITH batteries installed (I have two units in hands right now). Anyway, still not a good information...
Keys in solderless units need a wider "angle" to reach the contacts. This is because their contacts are provided by "plastic bubbles" under each key; they use a flex circuit and the (amazing) solution was using a single plastic assy with the contact surfaces and circuit trails for the IC's and both contacts for keys. The "bad news" is that the cooper in the bubbles seems to suffer a "movement stress" and tend to "crack" in old, too-used units. I saw a few calculators with this sort of trouble, but it happens. I think a brief "description" of these angles will help you better:
- choose one of the keys in the first row (e.g.: prefix keys) and look at one of its side while you press it;
- observe the face that's closer to the display when the key reaches the end-of-course;
- if the mentioned face has more than half of it hidden in the keys' hole, it's a solderless unit;
- if just a small part of it (less than a half) is hidden, i.e., it moves a little bit only, it's a soldered unit.
Units with soldered IC's have metal caps for key contacts, the same kind used in the HP41 series. That's why they need a different "angle".
Hope this helps identifying your unit. And if it is a solderless unit, chances are you have a bad contact somewhere in the many contact surfaces. To open it... well, that's another story. If you have no clues about where to go after removing the two screws under the batteries "door" and you realize there's something still keeping both upper and lower halves togehter, hold on for a while.
Let us know if you need guidance to "accomplish the mission".
And congrats! Among the LED-display models, I consider the HP34C along with the HP67/97 and the HP55 as the best ones. Yes, I know that are others like the HP65, all Topcats... But many of them are great collectible items and, except for the HP55, these are some of the easiest to find.
Luiz (Brazil)
Edited: 26 Dec 2003, 1:36 a.m.