From: Katie
Email: katie@wass.net
After re-reading your post, I think that I misinterpreted "decimal digits" to mean decimal points. I assume that what you're saying is that the broken calculators are simply displaying all zeros, or some other fixed pattern. If that's the case, the most common problem that I've found is a stuck key. Since the keyboard scan circuitry in most older machines can't do multi-key roll over, if one key is stuck down (electrically if not physically) it will lock out all the other keys. The fix is to open the keyboard (often held together with several small screws) clean the contacts and the keys and reassemble it. Be careful to note all the key positions before you take it apart (I like to put it on a flatbed scanner and print a picture of it) and to keep an eye out for springs and contacts that will fall out when you remove the screws holding it together.
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