HP97 The journey begins

[rprosperi]

@Tony - I guess I missed some details earlier, so a couple quick questions:

a. Will a Spice with your new board and LiPo batteries be able to be charged using the original AC Adapter?

b. Are the LiPo batteries "AA" form factor and replaceable, or some semi-permanent installation in the battery bay?

Thanks

[teenix]

No, the LiPo has its own charger built into the calculator. It just needs a USB cable to 2.5mm jack, available on web for a few $. The jack plugs into the original charge port at the top of the calculator. Or you can charge it externally with one of those cheap USB LiPo chargers.

The replaceable LiPo I chose fits nicely into the battery bay, also available from web. I have link references for both battery and cable in the user manual.

Pic attached.

cheers

Tony

(04-28-2023 10:24 PM)rprosperi Wrote:  @Tony - I guess I missed some details earlier, so a couple quick questions:

a. Will a Spice with your new board and LiPo batteries be able to be charged using the original AC Adapter?

b. Are the LiPo batteries "AA" form factor and replaceable, or some semi-permanent installation in the battery bay?

Thanks

[rprosperi]

(04-28-2023 11:58 PM)teenix Wrote:  No, the LiPo has its own charger built into the calculator...

Thanks Tony, I'll look for the manual (if it's out there already?) and catch-up on some stuff it seems I've missed.

[tangdfx]

Hello，tony

Is it possible to have an alternative choise to use normal AAA battery.

[teenix]

(04-29-2023 02:41 AM)tangdfx Wrote:  Hello，tony

Is it possible to have an alternative choise to use normal AAA battery.

The new CPU board needs a minimum of around 3.6V to operate properly. There is no switched mode power supply like the original. The LiPo seems to produce about 3.8 - 4.2V which fits in with the low batt detect and it also fits in the case without stress.

cheers

Tony

[teenix]

(04-29-2023 01:27 AM)rprosperi Wrote:  Thanks Tony, I'll look for the manual (if it's out there already?) and catch-up on some stuff it seems I've missed.

I've uploaded a preliminary PDF file here

[teenix]

Hi all,

Tentative steps, seeing how things are going to fit together for the 19C. What a thing to try and assemble :-)

cheers

Tony

[Paul Dale]

I kind of wished I'd kept my 19C for you to experiment upon to expedite this most worthwhile project.

It worked perfectly and I passed it on.
Sigh, live and learn.

[tangdfx]

Great news. Waiting for new HP19c board.

[Massimo Gnerucci]

Tony, you are the Master!

[teenix]

(05-20-2023 08:07 AM)Paul Dale Wrote:  I kind of wished I'd kept my 19C for you to experiment upon to expedite this most worthwhile project.

It worked perfectly and I passed it on.
Sigh, live and learn.

It's always the way, as soon as you give something up, whether junk or not, you end up needing it. Just today, I needed something to bend some cable for the 19C prototype. I ended up using a bit of scrap aluminum I've had for years. I originally made use of it to hold something in place on an old 1942 Harley while I tightened something else. I also used it to hold a blade while cutting tubing for a gummy wheel repair.

cheers

Tony

[Chr Yoko]

(04-29-2023 03:20 AM)teenix Wrote:  

(04-29-2023 02:41 AM)tangdfx Wrote:  Hello，tony

Is it possible to have an alternative choise to use normal AAA battery.

The new CPU board needs a minimum of around 3.6V to operate properly. There is no switched mode power supply like the original. The LiPo seems to produce about 3.8 - 4.2V which fits in with the low batt detect and it also fits in the case without stress.

cheers

Tony

Hi Tony, if you are using Li Ion batteries, please make sure they have their BMS included. A BMS is the battery management system circuit board that will protect the cell from under voltage, over voltage and over currents. It has also a temperature probe. This is important for safety.

In case you create a short in the calculator, you do not want it to burst into flames and white toxic smoke.?

[Jonas Sandstedt]

Tony,

The HP-19C boards looks stunning!
Just out of curiosity, how do you plan to connect the two boards to each other and to the LED display? The original uses the resilient “fingers”, but I guess these are not standard components of today? Should the resilient “fingers” be moved from the broken board to the new replacement boards?

Best regards Jonas

[teenix]

(05-26-2023 09:24 AM)Jonas Sandstedt Wrote:  Tony,

The HP-19C boards looks stunning!
Just out of curiosity, how do you plan to connect the two boards to each other and to the LED display? The original uses the resilient “fingers”, but I guess these are not standard components of today? Should the resilient “fingers” be moved from the broken board to the new replacement boards?

Best regards Jonas

Thankyou.

The boards are still in a prototype stage, so anything can change.

The Battery/Printer board is very similar to the original and (hopefully) will use IDC board to board connectors to the CPU board. The trick is that the top case halve rotates into the bottom case so the pins have to allow for this. The CPU board connects via a ribbon cable which can be inserted into the socket on the key/display board the same as the original.

Unfortunately, the only thing I cannot do is provide a connector to the display, so as you mention, the fingers (which are unobtainable and I have not seen any replacements), will have to be transplanted to the new board. I wouldn't advise soldering a modern socket to the LED display board as the plating on the holes will generally be corroded or blackened and tarnished and it will be difficult for the solder to take. These displays are manufactured similar to the Spice so they too may be damaged by excessive heat, movement or shocks which can dislodge the tiny 7 segment chips from the circuit board and may damage the tiny connecting wires too.

If someone cannot solder, but can unsolder them, they can be sent to me if desired and I will fit them. It will be a bit fiddly, but shouldn't be too hard. I may be able to make up a jig to help out. They can probably be taped inside a Get Well card which should be cheap to mail.

cheers

Tony

[tangdfx]

Hello，tony

I search the taobao website and find the replacement of these finger.[attachment=12157]

Do you think is it could be use？

[teenix]

(05-26-2023 01:33 PM)tangdfx Wrote:  Hello，tony

I search the taobao website and find the replacement of these finger.

Do you think is it could be use？

Hi there, thanks for taking the time to look.

From the picture, it is hard to say. The only way would be to try some out physically.

cheers

Tony

[teenix]

Hi all,

The 19C CPU is slow going.

I assembled most of the main board and tried a fitment inside the calculator case. I didn't notice that there are locating flanges molded on the inside of the case and some of the component placements stopped the case closing properly. Unfortunately, there was no way around this so a board re-design was required. Things are very tight inside around the printer setup so there is not much room for errors.

Another tricky bit will be the clamshell way of closing the top and bottom halves (each with a circuit board) and making sure the board to board connectors mate ok. The trouble of course nowadays is that you need to find suitable off the shelf connectors.

I have a new board already and will have another go at populating it.

It is somewhat difficult to do while temporarily staying in a caravan with about 6 square feet of bench space, but getting there.

cheers

Tony

[tangdfx]

Good news.

Keep going.

[teenix]

Hi all,

The 19C work is still going on behind the scenes.

I've managed to connect the CPU board to the battery board with FFC cable and have attached battery contacts to the circuit board. These are not the same as the original, but still have the same contact area. I don't have an original battery, so it is just a bit of guess work.

The battery board (frustratingly) is still a work in progress. As soon as I get it constructed something I don't notice (until the time comes) rears its ugly head and won't fit properly. Things like tiny lugs molded into the printer housing which are inconspicuous until you realize what they are there for.

The interconnects between the two boards have been a bit of a problem. Mark Flemming offered a tip which I think will help alleviate one of the issues. The 19C is a real tricky design, which for those that have opened it and tried to reassemble would no doubt know. There is not much that can be done, so this design won't offer much relief in that area.

Anyway, I powered the battery board up and the main power switch is doing what it is supposed to do. Next, I will start populating the new design CPU board and try to get the processor going.

cheers

Tony

[tangdfx]

Great news. More faster than I estimate.