Had this calculator for some time now. Can’t remember how I got it, but it didn’t work as it ran on batteries and not solar power. I never had the time to open it up back in the day, so I stashed it in a storage banker’s box. I found it recently after looking for some supplies, and thought I would take a crack at it.
First things first. I needed to remove the six small screws located on the back of the unit. After removing the chassis, I replaced the LR44 type button Lithium batteries. Luckily, the unit did turn on, but unfortunately, the LCD display did not function correctly. When you test it for functionality, it is best to just use the number 8, since it uses all the lines that conform to the single contained area, like drawing two squares that connect one on top of the other. Unfortunately, the number 8 appeared as 7’s 5’s and 3’s in many of the areas on the screen. After taking a better look at the screen, I noticed that there were no cracks or leaks from the liquid crystal.
Since there was a number in each slot, I concluded that the ribbon cable was not severed. My next guess was that there was a part of the cable that wasn’t making a connection properly. I wasn’t sure where the connection issue was, whether it be on the circuit board or the LCD itself. So, I whipped out the old hair dryer and started to heat up both areas of the ribbon. The technique I used was to go in a circular motion pattern, that way you don’t overheat a specific area and destroy the components. I had to do this several times as I didn’t spend enough heating time on an area. Each time I ran the hair dryer, I spent twice that time letting the calculator cool down before testing it out. I also ended up heating the area directly on the LCD, as one of the digits was quite stubborn. Just remember to go in a circular pattern, and go SLOW. All of this has paid off, and now I have a fully functional calculator again!