Braun ET66

Braun designed the ET66 in 1987. The designers were Dieter Rams and Dietrich Lubs, according to the Victoria and Albert Museum in London, which lists it as type 4776. It is a black plastic pocket calculator with round, domed keys and a sliding protective sleeve. Braun's calculators started earlier. Museum Angewandte Kunst in Frankfurt says the company added pocket calculators to its range in 1976, when they were becoming popular. It based its device on a slightly modified model from the Japanese firm Omron. Lubs and Rams designed the interface, and they used color to put the most important functions forward. The code is simple. Number keys are black. Function keys are brown or a muted green. The on and off switches are green and red. The equals key, the one pressed most often, is yellow, and the museum calls that yellow key a Braun trademark. The keys are convex, which the museum says makes them more comfortable to press. Brief operating instructions are printed on the back. The V&A's gallery label calls the ET66 one of the most successful designs Braun produced while Rams was its chief design officer. Braun gave one to the Centre Pompidou in Paris in 1992. One example in the Thimet calculator collection in Germany came boxed with an instruction sheet dated 1996. The surprising part came twenty years after the design. In 2013 Core77 noted that the iPhone's calculator app had looked much like the ET66, before Apple changed it to rectangular keys. In May of that year Braun announced a reissue, model BNE001. Thimet notes that the new version was made under license by Zeon Ltd in London.

Everyday sums on a desk. The ET66 does basic arithmetic with a percentage key and one memory register, on an 8-digit LCD, according to the Thimet calculator collection. A study in industrial design. The ET66 is held by the V&A in London, the Centre Pompidou in Paris and Museum Angewandte Kunst in Frankfurt. The color code makes the layout readable at a glance: black for numbers, brown and muted green for functions, yellow for equals. A pocket object. The calculator measures 13.6 by 7.8 by 1.1 cm (5.4 x 3.1 x 0.4 in), and the sleeve slides over the keys for carrying, per the V&A. Where it falls short: it is a basic calculator. Thimet lists no exponent and no programming, and the display stops at eight digits. It runs on a button cell, not solar power. A cell left inside for years can leak. Owners report that the keys of 1980s examples wear. A Core77 reader with an ET66 from that decade wrote that its buttons did not last long. The 1987-era calculator and the 2013 reissue look alike, so a buyer who wants one or the other needs to know the model number.

Fit a fresh cell first. Thimet lists one button-sized cell, and battery suppliers list it as a 357/LR44 size. One owner of a type 4776 wrote on JustAnswer that new cells did not help, and that cleaning the battery contacts brought the calculator back.

Press every key once and watch the display. Calculator.org explains that keys on pocket calculators often fail when dust gets between the rubber contact membrane and the board. A Core77 reader who owned a 1980s ET66 wrote that its buttons did not last long.

Enter 88888888 and look for gaps in the digits. Calculator.org says the display often connects to the board through a rubbery strip that loses its elasticity with time. If gentle pressure just below the display brings the segments back, that strip is the likely cause.

Look inside the battery compartment. Calculator.org warns that cells left in a stored calculator can leak, and the residue corrodes the contacts.

Look for the model number. The V&A and the Thimet collection list the original as type 4776. Braun's 2013 reissue is sold as model BNE001, according to Core77, and Thimet notes that it was made under license by Zeon Ltd in London.

The ET66 came with a sliding protective cover. The V&A lists the calculator and the sleeve as two parts of one object. The example in the Thimet collection came with its cover, an instruction sheet and the box.

Calculator.org names an exhausted cell as the most common calculator problem. The ET66 takes one button-sized cell, according to Thimet. Replacing it is the first step, and it is home work.

A leaking cell leaves residue that corrodes the terminals. Calculator.org's fix is to remove the spent cell, clean off the corrosion with a slightly damp cloth, and scrape the contacts down to shiny metal. A type 4776 owner on JustAnswer reports that cleaning the contacts brought the calculator back. This is careful home work.

Calculator.org traces dead keys to dust between the rubber contact membrane and the board. The fix is to open the case, lift the board, and wipe the conductive pads and the board with a damp, lint-free cloth. Work face down, because loose keys can fall out. No ET66 service manual turned up in the sources, so opening the case is work for someone used to small electronics.

The rubbery connector between the display and the board loses its elasticity with age, says calculator.org. Pressing on the case below the display can bring the segments back for a while, and a thin shim can hold the contact. This is delicate work.

Calculator.org says there is little to do here except replace the display. For a calculator out of production, that means finding a matching display.