1515C calculator


My calculator stuck in the USER mode.f+ USER key does not reset the mode back to normal.

I performed all of the tests recomended in te user's manual, including taking out the bateries and shorting battery terminals with batteries in.

They all show that the 15C is working fine.

Do you know if there is a specific sequence of key stroks that would reset it.

Please help.




Hi, Burhan;

please, forgive me if the question goes above what you have already done, but I am curious about one fact: after shorting the batteries terminals in the calcualtor, did you get the

[  Pr Error  ]
message in the display? This is important to notice, because this is the (only?) way to be sure the calculator had its (user) memory cleared and all setting are in their default state. If you did not get the
[  Pr Error  ]
message in the display, chances are your HP15C still maintains prelious contents.

If you saw the Power Error message and you still have the [USER] annunciator lit, have you tested to see if the calculator behaves accordingly?

In any event that you cannot see the solution for this particular issue, at least you have a rare unit in hands. Not a consolation, though, and please, forgive me if it 'sounded' pun; not inteded, believe me. I had two old HP31E (Spices) and one of them had the following peculiarity: after the [STO][ENTER] self test, registers R1, R2 and R3 had their contentes altered to some not-zero value, althought the test itdself finished O.K.:

As I know that one of the Brazilian contributors at the MoHPC has many calculators and he is a collector, I sent him this particular unit to be taken as a curiosity. And because this is not a common behavior, the unit itself is a rare one, as seen by collectors...

Please, let us know how it goes. And success!

Luiz (Brazil)

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