|Halfnut dismantled (with images!)|
Message #1 Posted by Vieira, Luiz C.(Brazil) on 27 May 2003, 4:17 a.m.
let's see how long will this provider keep my images...
Well, here it comes. This is a comparison between halfnut (left) and fullnut (right) PCB, front view. The small black holes in some of the fullnut PCB's holes (nine) indicate the difference between them, concerning to their respective cases. I have successfully used an HP41CV's halfnut PCB in an HP41C's fullnut case. I had to remove the small plastic "posts" where indicated by the black holes.
This is a back view of the halfnut's PCB; that's what you see when opening the calculator. The red-and-black wires shown in the top of the image were added to connect external batteries; they do not actually exist in the calculator. Also, both electrolytic and tantalum capacitors were positioned that way so I could scan the image; actual position is shown in the small additional image.
This shows the halfnut LCD removed from the mainboard. If you look at previous picture, you'll see there are eight small metal strips around the LCD's hybrid chip (upper, part. # 5061-7255), four in the top (easily visible) and four right below the hybrid itself (not so easily visible, they are like dark mark in four round holes). It's necessary to slightly unfold them in order to remove the LCD. What you see below the LCD is the not-usually visible set of connectors from the hybrid 5061-7255.
I decided to go further and removed the LCD driver from the mainboard in order to try to find sny problems, like short-circuited or open trails, cold soldering... but I found no trouble. This HP41CV's halfnut PCB returns .END. REG 63 after SIZE 000, calculator memory cleaned. It should return .END. REG 319. I rebuilt everything back and it is working fine for an HP41C!
These images show a sequence where a fullnut LCD is disassembled. The two small "lockers" (black flat fasteners) are made of plastic, and are easily removed. I must warn that it's necessary having careful hand and fingers movements; if you force too much, you may bend the metal bridges or even break their soldering tabs, permanently damaging the LCD assy. After inspecting aligned pads for both LCD's I got to the conclusion that fullnuts' and halfnuts' LCD's are not interchangeable; I mean the LCD itself, the glass parts, not the drivers. (sorry, Gordon)
As I'm having more information, I'm posting. I hope these images help others.
Feedback is always welcome.
Thanks and enjoy.
Luiz C. Vieira - Brazil