Sharp EL-506H

Sharp EL-506H

The EL-506H was a scientific calculator manufactured by the Sharp Corporation of Japan in the mid 80s. It was one in a series of calculators consisting of EL-506X, EL-506W, EL-506P, EL-506V, and EL-506G. The EL-506H had the SC6767S processor based on CMOS technology, and consequently, its power requirement was 0.0004-watts. It required a pair of 1.5 V button cell batteries that could last for many years. For the replacement battery, it will operate fine on AG13 type batteries commonly available in thrift stores.

It had a simple layout, with the most used functions directly available without any fuss. The key spacing was wide enough and the membrane keyboard was comfortable to use. It was an early design that was not overly complicated and had the basic functions you needed right at your fingertips. Many students of the 80s will remember having one of these and be seeking for it.

Inside View

I recently cleaned mine and took it apart for repair and service. The membrane part of the keypad can accumulate dust over the years and required cleaning. The copper contacts on the PCB also required some cleaning with an electrical contact cleaner.

PCB Side Keyboard Contacts

I cleaned mine with some nice electrical contact cleaner, and now it should now last for many more years to come.

Battery Contacts and Spring Clips
Clip Mating Pads - Repair

On this model, the spring clips for the battery connector mate with copper pads on the PCB. Unfortunately, they (at the factory) placed blobs of solder over the pads, which over the years reduce the conduction due to oxidation. This often results in the display flickering and loss of power intermittently. All I had to do was to remove the tarnished old solder and tint a layer of new solder and it fixed the problem.

Keyboard Membrane

Here is the keyboard membrane.

Scientific Calculator

It is a nice little calculator would be difficult to find today. Over the years, their numbers are reducing and therefore the prices will obviously go up. If you can find one with the leatherette-type wallet case and manual in mint condition, then it could fetch a packet on eBay on the right day.