HP-15C CE often freezes

[BuSchu]

I have been experimenting recently, especially in 15.2 mode. I added an input routine to the Sudoku solver (https://hp-15c-simulator.de/programs/Sud...Solver.htm) and started it twice. The first run was quite normal, after a few minutes the correct result was calculated. But the second run with different data ended with a frozen “running” in the display. Only reset helped. Have you also experienced this or is it possible that my copy is defective?

[rprosperi]

(10-25-2024 12:01 PM)BuSchu Wrote:  I have been experimenting recently, especially in 15.2 mode. I added an input routine to the Sudoku solver (https://hp-15c-simulator.de/programs/Sud...Solver.htm) and started it twice. The first run was quite normal, after a few minutes the correct result was calculated. But the second run with different data ended with a frozen “running” in the display. Only reset helped. Have you also experienced this or is it possible that my copy is defective?

Here's a few things to consider:

a. It's possible this is a battery issue. When you have programs that run for many minutes consecutively on a 15c CE (equiv to hours or even days on an original 15C), it can dramatically drain batteries, so check this first.

b. Does it behave differently in default mode than in 15.2 mode (which you mentioned)? Very unlikely, but worth checking

c. If all checking fails, post the modified program and other folks can enter it and see if the problem can be reproduced

Please follow-up with results and findings to benefit future readers.

[BuSchu]

Now I have experienced the following: Since I am ill, I only entered a few program steps and then switched off the calculator while it was in programming mode. When I switched it on again, it showed the last program step entered and was frozen. I will exchange it.

[AnnoyedOne]

(10-25-2024 02:07 PM)BuSchu Wrote:  ...and was frozen.

Sounds like a faulty CPU clock to me. Perhaps a bad RC oscillator solder joint.

You could try the naddy "drop it" technique

https://www.hpmuseum.org/forum/thread-22536.html

A1

[rprosperi]

(10-25-2024 02:07 PM)BuSchu Wrote:  Now I have experienced the following: Since I am ill, I only entered a few program steps and then switched off the calculator while it was in programming mode. When I switched it on again, it showed the last program step entered and was frozen. I will exchange it.

Indeed, this unit seems to be defective, I would definitely request exchange ASAP.

[Divasson]

Before deciding that the unit is defective, I would exchange the batteries and test again.

The programs that run over a long time drain the batteries extremely fast, since the machine is running at full speed (48Mhz) which consumes several orders of magnitude more energy than at idle. And at idle the battery voltage level is high enough to not lit the low battery indicator, but this voltage level drops fast when running a program or a solve/integrate procedure due to the battery's high internal impedance.

Your unit's behavior is very much like when I had to change batteries (after 1 year of use, and with a back up of the memory!)

[BuSchu]

The calculator now freezes almost every time I switch it on. I will definitely be returning it. I've only had it since the end of September.

[Steve Simpkin]

(10-27-2024 06:27 AM)BuSchu Wrote:  The calculator now freezes almost every time I switch it on. I will definitely be returning it. I've only had it since the end of September.

Have you tried putting new batteries in it?

[BuSchu]

Now after switch on. The Batteries are OK. Never seen the asterisk.

[Steve Simpkin]

(10-27-2024 09:24 AM)BuSchu Wrote:  Now after switch on. The Batteries are OK. Never seen the asterisk.

You might want to try new batteries anyway. Coin batteries often lose their current capacity before their voltage drops very much making them hard to create an accurate low battery indication.

[Thomas Klemm]

(10-27-2024 09:24 AM)BuSchu Wrote:  

Ach! - Die Venus ist perdü -
Klickeradoms! - von Medici!

[dm319]

(10-27-2024 09:24 AM)BuSchu Wrote:  

[BuSchu]

(10-27-2024 09:56 AM)Steve Simpkin Wrote:  You might want to try new batteries anyway. Coin batteries often lose their current capacity before their voltage drops very much making them hard to create an accurate low battery indication.

Thank's a lot, Steve. You are right. I tested the batteries with my multimeter: Open curcuit 2,9 V, under load 2,5 V. Seems to bee too little for the calculator. But the empty battery indicator also seems to be a waste of time. :-(

With new batteries, the calculator runs like new again. But if the batteries run out, you can lose the fun of using the calculator. It's a collector's edition.

[AnnoyedOne]

(10-27-2024 02:48 PM)BuSchu Wrote:  With new batteries, the computer runs like new again.

Which is why, IMO, one should keep replacements available. I do that for all kind of batteries.

Some prefer rechargeable cells. Those have never worked out well for me. They often "die" quickly and then don't charge all the way back up.

A1

PS: My guess is that the power (the batteries are in parallel not series) was too low for the RC oscillator to run. Hence "freezing".

[Maximilian Hohmann]

Hello!

(10-27-2024 03:05 PM)AnnoyedOne Wrote:  Which is why, IMO, one should keep replacements available.

Not replacements, but rechargables. LIR2032 batteries (the rechargable Version of the CR2023) cost hardly more than good throw-away ones. They claim that they last 400 charging cycles. The last ones I bought were 1.80 Euros a piece, prices for USB chargers start at around 2 Euro. After the second charge they have paid for themselves.

Regards
Max

[DA74254]

(10-27-2024 03:21 PM)Maximilian Hohmann Wrote:  Hello!

(10-27-2024 03:05 PM)AnnoyedOne Wrote:  Which is why, IMO, one should keep replacements available.

Not replacements, but rechargables. LIR2032 batteries (the rechargable Version of the CR2023) cost hardly more than good throw-away ones. They claim that they last 400 charging cycles. The last ones I bought were 1.80 Euros a piece, prices for USB chargers start at around 2 Euro. After the second change of batteries they have paid for themselves.

Regards
Max

Hello,

Are these obtainable within EU for the price mentioned?
If so, can you reveal your source?

[AnnoyedOne]

(10-27-2024 03:21 PM)Maximilian Hohmann Wrote:  

(10-27-2024 03:05 PM)AnnoyedOne Wrote:  Which is why, IMO, one should keep replacements available.

Not replacements, but rechargables.

If they work for you great. Almost every time I've gone to use something powered by rechargeable batteries they've been low so I had to use non-rechargeables anyway.

A1

[AnnoyedOne]

(10-27-2024 03:25 PM)DA74254 Wrote:  If so, can you reveal your source?

I've done some web searches and all the "cheap" ones I've found are "Made in China". The same with the chargers. Probably online only.

Brand name ones will cost you a lot more.

A1

[Maximilian Hohmann]

Hello!

(10-27-2024 03:25 PM)DA74254 Wrote:  Are these obtainable within EU for the price mentioned? If so, can you reveal your source?

Yes, of course! I bought them at Conrad Electronic (who is in Germany what Radio Shack is in the US): https://www.conrad.de/de/p/voltcraft-lir...lsrc=aw.ds

Regards
Max

[BuSchu]

Very interesting! Thanks!