HP31E strange behavior after [STO][ENTER]



#2

Hi folks, Spice people; (Norm, you're gonna like this)

first of all, I cannot say a word about what happened before calculator's maintenance because I observed the fact today, meaning May, fifth. Also, after opening, repairing, maintaining and closing some Spices for the last two months, I have no idea if the back case of this HP31E is its original one, so I cannot tell you its serial number. All I know is that this one came to my hands with a "MADE IN BRAZIL" back case, and seemed never being opened before.

This is an HP31E that has soldered IC's and it returns

[-8,8,8,8,8,8,8,8,]
after [STO][ENTER], and that's fine for me. Anyway I decided to play with it and, just for fun, I wanted to see [ Error 3 ] and began to ReCalL available registers (Ro to R3 in this Spice). No problem: with the
[-8,8,8,8,8,8,8,8,8,8,]
still in the screen, it would be enough to press any key to clear the display to 0.00. Still according to the manual, all memory is cleared after [STO][ENTER], meaning stack and numbered registers.

Then it comes the weird stuff:

[RCL][0]     [ 0.1000     ]
[RCL][1] [ 10.0000 ]
[RCL][2] [ 100.0000 ]
[RCL][3] [ 1,000.0000 ]
[RCL][4] [ Error 3 ]

I was not worried because [STO][ENTER] returned the all-eight's display and that should mean the calculator is fine. So I decided to go further:

[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx] [ 0.0000 ]
[f][CLALL] [ 0.0000 ]
[RCL][0] [ 0.1000 ]
[RCL][1] [ 10.0000 ]
[RCL][2] [ 100.0000 ]
[RCL][3] [ 1,000.0000 ]

I could not believe that was happening. I insisted:

[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx] [ 0.0000 ]
[f][CLALL] [ 0.0000 ]
[f][CLALL] [ 0.0000 ]
[f][CLALL] [ 0.0000 ]
[RCL][0] [ 0.1000 ]
[RCL][1] [ 10.0000 ]
[RCL][2] [ 100.0000 ]
[RCL][3] [ 1,000.0000 ]

How come? I tried another approach:

[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx] [ 0.0000 ]
[CLx] [ 0.0000 ]
[x<>Y] [ 0.0000 ]
[f][CLALL] [ 0.0000 ]
[f][CLALL] [ 0.0000 ]
[f][CLALL] [ 0.0000 ]
[RCL][0] [ 0.1000 ]
[RCL][1] [ 10.0000 ]
[RCL][2] [ 100.0000 ]
[RCL][3] [ 1,000.0000 ]

Now the last experiment:

[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx] [ 0.0000 ]
[f][CLALL] [ 0.0000 ]
[RCL][0] [ 0.1000 ]
[f][CLALL] [ 0.0000 ]
[RCL][0] [ 0.0000 ]
[RCL][1] [ 0.0000 ]
[RCL][2] [ 0.0000 ]
[RCL][3] [ 0.0000 ]
[RCL][4] [ Error 3 ]

Recalling any of the registers after [STO][ENTER] will allow [f][CLALL] to clear all memory. It seems as if the calculator is "stuck" and does not finish [STO][ENTER] routine unless a register is recalled, even forcing [f][CLALL] not to work properly.

Another fact: I also tested another HP31E, "sandwich-type", and I got:

[STO][ENTER] [-8,8,8,8,8,8,8,8,]
[CLx] [ 0.0000 ]
[RCL][0] [ 0.0000 ]
[RCL][1] [ 0.0000 ]
[RCL][2] [ 0.0000 ]
[RCL][3] [ 0.0000 ]
[RCL][4] [ Error 3 ]

No matter at all, no strange behavior. This one had a "MADE IN SINGAPORE" back case.

This is just to add another (bug?) "report" to all other Spices' ones. Or to help others with the fact that Spices may have a fucntional degradation after being repaired. In this case, the calcualtor has soldered IC's and I cannot say a word about its behavior before maintenance (replacing flex for wires).

Luiz C. Vieira - Brazil


#3

Somewhere I remember reading that you have to power the machine off and on after the self test to make sure it is ready for the real world.


#4

Hi, David;

as it is not a continuous-memoy unit, this would indeed be a solution.

Thank you.

Luiz C. Vieira - Brazil


#5

I think it also applies to the continuous memory models. I think some internal registers in the CPU get loaded with non-normal values. Since the CPU is powered off in the "C" models, it gets reset when the system is powered back on.


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