|HP 41CL, thoughts...pics...part 1 (new pinout cap picture)|
Message #1 Posted by Geoff Quickfall on 13 June 2011, 8:11 p.m.
in one word "incredible".
well some more thoughts first. My donor is serial numbered 1933Axxxx (thanks Gene) making it a very early example with the "tall keys" keyboard. I used this donor because the case is pristine as is the battery module block and battery posts. The logic pca is dead, and I still haven't trouble shot it as yet. I also wanted to use the 'oldest version of 41C' that I had, just to contrast with the newest technology supplied by Monte.
After a thorough cleaning I was preparing to install when I read Monte's warning to READ the installation manual. Usually I don't! This time I did!!
According to Monte's installation instructions there is a warning about differing revisions on the LCD display. Revision F LCD panels need an installation of a .01uF from the OS1 pin out on the keyboard pca pinout. The ground is pin two of the keyboard logic pca. These two pins can be found at the LCD pinouts at the top of the keyboard pca also (see the pinout diagram at bottom of posting). This LCD pinout would be the easiest area to attach the 0.01uF capacitor. I will do that tomorrow.
the HP 41C serial numbered 1933A which is below the cutoff of 1954A. This means that I need to add the 0.01uF cap. Note the shinier keyboard bezel. Missing is the textured matte surface of later 41Cs.
Opening the case and placing the back aside, here are the sequential shots after removing the 41C original logic PCA:
Close up of the wired connector recommended by Monte and others:
The AC ball and springs connector as well as the original nuts that hold the oldest HP 41C logic pcas:
Close up of the original PCA obverse and reverse followed by Montes new 41CL:
You can see the quality in Montes 41CL, wonderful:
While you are here, clean the wire wrap connector with a soft natural brush stroking it the parallel to the wrapped wire. Also clean the battery-module block on all three sides. Insure continuity and that the pressure foam is still expanded. Clean contact surfaces of the keyboard pca. Dry and blow off dust when reassembling:
Now adding the serial bus port and double sided tape to hold the wire in place:
And now the CL in position:
Tomorrow, using Monte's emailed instructions and this excerpt from the HP41C manual illustrating the rev 7 LCD drivers attachment point and pinouts for the LCD:
Here is a close up on the revision 7 LCD drivers, as evidenced by the plastic caps as opposed to epoxy blobs:
As I said, standby for further!
edited as per typo indicated by Gene and other stuff.
Edited: 14 June 2011, 12:33 a.m.