Tag: Monroe

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Monroe 430 Calculator repair and cleanup

I man­aged to snag a Monroe 430 cal­cu­la­tor that was in good con­di­tion and a rea­son­able price. The Monroe 430 is 14 dig­it four-func­tion cal­cu­la­tor with mem­o­ry, per­cent, and a few oth­er extras. I have worked on a mod­el 425 and 420 in the past so I kind of knew what I was get­ting into, espe­cial­ly the lack of documentation.

Monroe 430 cal­cu­la­tor with 14 dig­its displayed
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Monroe 650 Calculator repair and cleanup

Welp, anoth­er cal­cu­la­tor tale of woe. This time it is a Monroe 650 cal­cu­la­tor found on eBay. The 650 is the top-end mod­el of Monroe’s 600 series cal­cu­la­tors. It is a 16 dig­it Nixie tube dis­play cal­cu­la­tor with addi­tion, sub­trac­tion, mul­ti­pli­ca­tion, divi­sion, square root func­tion, and two mem­o­ries. It oper­ates in fixed dec­i­mal or float­ing point modes, and has 5 chang­ing indi­ca­tors spaced every incre­ment of the base-10 expo­nent of three from the dec­i­mal point.
The price was right and includ­ed free shipping.

Monroe 650 cal­cu­la­tor after cleanup and repairs
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Monroe 40 Calculator Refurbishment

An ear­ly hand­held cal­cu­la­tor from 1974, with a 10 dig­it Panaplex dis­play and recharge­able bat­tery.
As I con­tin­ue search­ing for Monroe 400 series cal­cu­la­tors, I came across this Monroe mod­el 40 cal­cu­la­tor at a rea­son­able price, with a few small issues.
Normally I don’t have an inter­est in hand­held cal­cu­la­tors as most are too new. This one caught my eye with it’s unique styling and 10 dig­it Neon Panaplex II display.

Monroe 40 hand­held cal­cu­la­tor side view
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