HP-39GII: Will it become a desired collectible?

[Massimo Gnerucci]

(01-16-2015 03:29 AM)walter b Wrote:  Sorry for that - it all started with post #24. You could see that in threaded mode easily as far as people replied properly.

d

Well, that quote is from a message in the old forum (7/2012); I don't think you can quote it directly here.

[Hlib]

HP-39gii inside



In parallel to the main power supply has arisen resistance value of approx. 300 ohm, wich is continuously discharged elements. I removed some of the electrical circuit components. The functioning of the calculator is not affected, but the problem persists. Probably, a fault is in the STMP.
When the voltage on the elements 1.3 V, only a short pulse of 5 V through USB can turn it on. And when the battery indicator shows 1 charge bar, after "Power OFF" the 39gii continues to consume current around 50 mA and kills the battery.
This is only a small part among all defects in this "system-on-chip", which it was present from the day of purchase. The HP has not brought apologizing to users, but started to advertise his next "monster".

[jebem]

(01-17-2015 12:59 AM)Hlib Wrote:  In parallel to the main power supply has arisen resistance value of approx. 300 ohm, which is continuously discharged elements. I removed some of the electrical circuit components. The functioning of the calculator is not affected, but the problem persists. Probably, a fault is in the STMP.
When the voltage on the elements 1.3 V, only a short pulse of 5 V through USB can turn it on. And when the battery indicator shows 1 charge bar, after "Power OFF" the 39gii continues to consume current around 50 mA and kills the battery.

Nice photos, thanks!
Sorry about your calculator fault.

I saw many situations where the current is well above the nominal value, and typically the problem can be related to faulty RAM or ROM memories.

Because the calculator can turn on, and assuming it can do normal calculations, I would replace the H27U1G8F2BTR NAND flash memory in first place.
However, I wouldn't recommend SMD devices replacements unless you have access to a professional workbench.

[Jim Horn]

Regarding the 39gII: I enjoy mine a lot. I don't have a Prime so this is as close as I can get. And considering the very stringent requirements for which it was designed combined with the circumstances that Tim has mentioned, combined with the huge body of code it represents, I'm delighted that it's available at all. It would be nice if the bugs were fixed. It would be nice if all the bugs in *any* large software project were fixed. But they have yet to impede my use of it.

Collectors here have often gone to great lengths to get older HP machines that couldn't do a tiny fraction of what the 39gII does. With it not having sold in large numbers, if there are collectors decades in the future, I wouldn't be surprised to see this one commanding a premium. Meanwhile, it serves me just fine.

(from someone who was excited beyond measure to get his HP-25 in June, 1975...)

[Hlib]

(01-17-2015 09:27 PM)jebem Wrote:  Sorry about your calculator fault.

(01-18-2015 01:00 AM)Jim Horn Wrote:  Collectors here have often gone to great lengths to get older HP machines that couldn't do a tiny fraction of what the 39gII does....Meanwhile, it serves me just fine.

Hi, Jose and Jim! Glad to hear that your devices operate well. Perhaps, my following notes will be useful to somebody.

1. During power 39gii on, there is an information read process from flash into RAM, and short-time rise of current up to 100...150 mA in a supply circuit is watched. A voltage of run out batteries falls to negative-going input threshold (Vit). The supervisory circuit monitors Vdd (or treshold voltage of reset) and keeps STMP-reset active as long as Vdd remains below the treshold voltage Vit. In this case calc. won`t turn on even if in the normal conditions batteries could work still very long. (Now it clear for me what for they set four batt. in parallel in 39gii). IMO, bad circuitry solution.
2. Periodically you should switch on and turn off this calculator during the long operation with it to avoid loss of results. In case of fatal hangup your new changes in data won`t remain. 39gii saves into flash the last status of RAM only after normal switch-off, not after abnormal extraction of batteries.
At least, my device always behaved quite so.

[factor]

Is it officially a "dead" product? Sad if it is true. Nice calculator, not a "toy".