|Re: HP 34C and HP 48GX questions|
Message #2 Posted by Vieira, Luiz C. (Brazil) on 8 Dec 2004, 6:33 a.m.,
in response to message #1 by Nick Nicholas
I own some Spices (HP3xE/C) and I think it's somehow easy to identify which one is a soldered or solderless unit. The fastest way is by comaparing two units so you can create your own reference, but there is a small keyboard test you can perform.
Pick one key (calculator ON or OFF), perhaps [ENTER] key and slowly press it till it "clicks" and stops. If the key's upper face (not the top of the key) hides itself in a way the top face almost reaches the keyboard level, then it is a solderless unit. If the key moves just a little bit and the upper face keeps half of it hidden and half appearing, then it is a soldered unit. This is because the solderless units have a single flex circuit that "plays the role" of keyboard contacts, circuit trails and IC's connectors, and the bubble caps for each key are somehow "far" from the keys contacts. The soldered units use metal caps almost like the ones used in the HP41 (and HP75C/D and HP71B) for each key, and their "moving range" is a lot smaller.
The other external "difference" is related to the weight. The solderless units have a "heavy" metal plate that assures the IC's terminals are uniformly pressed against the IC's tabs in the flex circuit, and this plate weights almost the weight of the batteries. So, a solderless unit without batteries weights almost the same as a soldered unit WITH batteries.
I also own two HP48G+, one with a blue-dot screen with a pale green background and another with black-dot screen with light gray background (same one used with the HP49G). With the calculators turned to off, it is somehow easy th see the difference by inspecting the background. I'm not sure if it is also easy to check for the difference when you have not seen each type as for having a parameter.
Hope this helps a bit.
Edited: 8 Dec 2004, 6:37 a.m.