Re: HP25 Programming Failure Message #2 Posted by Randy on 5 May 2007, 1:54 p.m., in response to message #1 by MikeG
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
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