LCD Spot Restoration

[hp41cx]

LCD Spot restoration

[mfleming]

This repair approach certainly looks feasible!

The damaged display comes from an otherwise working HP22S. The display from an HP14B donor was used to repair the 22S. The picture sequence shows how I went about using the suggested display repair approach on the leftover damaged display.

The top row of pictures shows the state of the damaged LCD. I used the blade of an Xacto knife to remove the LCD backing shown in the second row. The third row shows how I cut a replacement backing from heavy card stock with a straightedge and knife. I used a spray adhesive on the card stock, then smoothed out the bubbles with a plastic tool. The last row shows the front and back of the repaired LCD. Sadly the 14B donor is no longer available, so I couldn't check to see if the display actually worked after the repair. I have no reason to think the display would not work again.

For anyone interested in trying this repair, removing a display from a Pioneer calculator involves carefully breaking an adhesive seal along the top and bottom of the display that holds the glass to the case. The upper and lower zebra connectors are also held in place on the LCD glass by an adhesive. If you remove the connectors they won't adhere back to the glass, so it may be best to leave them in place when you clean the rear of the display glass.

The spray adhesive I used to hold the card stock backing in place left a visible (though not too distracting) cloudy appearance to the back of the display. It might be better to use a line of adhesive or double-sided tape along the top and bottom of the card stock where the LCD is hidden by the case window from view.

A big thanks to hp41cx for finding and posting this repair reference!
~Mark