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HP25 Programming Failure - Printable Version

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HP25 Programming Failure - MikeG - 05-05-2007

Does anybody know the cause where by none of the functions/keys are stored via program. [n1]

Example in PRGM mode: (Program cleared first)

Key in G 2 (x^2) Display: 01 40

Key in G . (pi) Display: 01 40

Key in x Display: 01 40

All keys and functions work in run mode though.


Edited: 5 May 2007, 12:32 p.m.

Re: HP25 Programming Failure - Randy - 05-05-2007

The problem is usually the result of a fried ram chip (1820-1564). The only source for a replacement is from another 20 series unit (27 excluded). The usual indication of the failure is 13 00 in all program registers that cannot be changed.

There are two other but less likely possiblities.

1) Corrosion on the circuit board, especially under the ram chip. Try standing the board in vinegar up to the battery contacts for an hour or so. Warming the vinegar first accelerates things. Then rinse the board very well and shake dry or blow dry with canned air. Let it dry well in a warm place overnight.

2) Common Woodstock problems