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Massimo Gnerucci · 08-20-2023, 08:07 AM

(08-20-2023 07:56 AM)teenix Wrote: Yay :-)

What else? ;)

Perfect job, as usual.

**rprosperi** · 08-20-2023, 12:01 PM

(08-20-2023 07:56 AM)teenix Wrote: Yay :-)

WOW, that must be an awesome feeling, well done Tony!!!

teenix · 08-23-2023, 05:54 AM

Another "yay" moment.

The PIK chip is responsible for detecting the print head in the home position at switch on. If it is not home, it will try to return it there ready for use.

My "PIK" chip had this function enabled today. I plugged in the motor and home switch wiring, moved the print head away from home and turned on the power. This all worked in code simulation, and luckily it worked in the real world too.

If the print head does not return in a certain amount of time, a message appears on the display, the printer is shut down and it is flagged as unusable until the next power cycle. In this state, regardless of the printer switch, or if any print function is enabled from the keyboard, the printer will not work.

If this printer is known to be faulty, a user can set a menu item to disable the printer as well.

After some playing around, I realized that the IDC pin CPU board to Printer board connector I have is unsuitable. It takes too much pressure to insert or remove it and I fear this will cause problems. Loosening the pins helps reduce the problem, but then the contacts become "iffy".

I sat down yesterday and redesigned both boards, so apart from the print head connections which have to stay there, the only others are 3 wires connecting the battery and switched print head power to the CPU board. You should be able to open and close the calculator fully without a problem. The Home, Motor and charger wiring now connects to the CPU board, but this doesn't matter.

Next is the printer operation where I have to start energizing the heads. It looks good on the scope, so it should print ok. There will be some fiddling with printed character spacing depending on the speed of the motor. This will be a hardware tweak, but the software also allows the user to set the print speed and intensity.

cheers

Tony

teenix · (This post was last modified: 09-01-2023 05:46 AM by teenix.)

Hi all,

I've been plodding away at the software and have made some gains.

I was purposely steering clear of the printer because it will be the first time I will have connected the print head to the driver. This is a bit worrisome because if the software fails and a head pixel stays on it will probably burn out fairly quickly.

I have monitored the output with a scope and all seems well, so then I connected some LEDs and they flashed while the line was "printed" and they all went off when the end of line marker was encountered. The motor sped up and homed the print head.

It all seemed to work so it was time to test with the head connected. The printer is a horrible thing to try and bench test with all the connections and I don't want to keep fiddling while the ribbon cable is floating around. I turned everything on, no smoke. I pressed PRx and the printer fired up but nothing legible was printed. I fiddled with the software to delay the character print start position on the paper but aside from the positioning, not much changed. I printed a long number and the printout was wider but still not legible.

I have the bench power supply current limited to hopefully avoid a mishap but should be enough to drive the heads. It may be the paper roll that is not well. Hard to say.

Anyway, I have the latest boards coming soon so that should allow me to assemble everything back into the calculator and have the printer fixed in position and lessen the chance of damage.

The new 19C CPU circuitry is much the same as for the Spice CPU board but the constant memory save at switch off was giving problems. It took a couple of frustrating days to find the culprit which was a capacitor in the print motor drive circuit. Once this issue was addressed, it started to work.

Not much to do now except wait for the boards, populate them and fingers crossed all over again :-)

cheers

Tony

tangdfx · 09-01-2023, 08:53 AM

Hi，Tony.

Well done.

Are you still use the original print paper together with the HP19C.

If yes you should use new paper.

The print paper will fading with the years past.

AndiGer · 09-01-2023, 10:26 AM

Hi Tony,

Guess you still have some good new(er) paper from development of the 97 PCB ...
Just cut some to 38mm wide to test with the 19C printer :-)

Andi

teenix · 09-01-2023, 11:38 AM

Thanks guys, I did think the paper might be problematic. It looks "old". Maybe if I unwind a few feet to get down into "fresher" paper.

Thanks Andi, I do have some 97 paper somewhere packed away, and it was printing bluish characters on the 97, so I will try to cut some down to width and try again.

Are new paper rolls for the 19C still available?

cheers

Tony

Massimo Gnerucci · 09-01-2023, 11:45 AM

(09-01-2023 11:38 AM)teenix Wrote: Thanks guys, I did think the paper might be problematic. It looks "old". Maybe if I unwind a few feet to get down into "fresher" paper.

Thanks Andi, I do have some 97 paper somewhere packed away, and it was printing bluish characters on the 97, so I will try to cut some down to width and try again.

Are new paper rolls for the 19C still available?

cheers

Tony

Sylvain's hint.

teenix · 09-01-2023, 11:31 PM

Thanks Massimo :-)

Jonas Sandstedt · 09-08-2023, 09:28 AM

Hello,

I recommend buying new 38mm paper rolls for at least two reasons. First, I think they provide a better print quality, and secondly you can buy roll that are free from bisphenol. Who knows which chemicals that are used for the old original HP rolls? Furthermore, these rolls can be used for several vintage printing scientific calculator, see picture and note the different type faces and styles.

I also want to mention that I have experimented replacing the original HP-19c printhead with a Seiko thermal printer head MTP401B (of the same type as used in the HP82240 printer) – and it worked. The connector is mirrored such that I have to twist the ribbon cable and add cut soldered connector pieces in copper tape (see pictures). The thermal head is not as wide as the HP counterpart, but a small item can be put in the HP-19c printhead holder to keep the new thermal head steady.

Misfortune 1: I accidently bent the new printhead during my experiments such that some of the tiny solder connections connecting the flex wire to the thermal head broke (see deteriorating results in picture), and I do not have a sufficiently small soldering iron. My heart sank and I ceased experimenting. Perhaps a heat gun can do the trick?

Misfortune 2: Seiko discontinued these products in 2021 and the small stocks that have been available for a fair price (about 8-9 Euros a piece) are, as far as I know, depleted.

Best regards Jonas

teenix · 09-25-2023, 05:43 AM

Hi all,

Slow progress, I have been inundated with offspring requests, I thought by now they would have grown out of that :-)

Anyway, I have some free time again, and I don't know why I didn't think of it before, but I placed the tip of my soldering iron so that it just touched the old 19C printer paper and it immediately turned dark blue, so I guess it still works.

I was able to jury rig the 19C for printing, not an easy task with the design of it, and after some fiddling to get the data output right, I managed to get a printout.

It seems a bit blotchy, so that may still be paper, or it may be because I am using a 1A bench supply. I have a 5V 3A supply somewhere, so I'll try to hook that up and see if the extra current available will help.

The first line appears to be offset by 1 digit for some reason, but after that it prints in line. On the face of it, it doesn't make sense, but I haven't come across many easy outs for problems with this project so this looks like it will be another.

The text looks a bit wide, so I'll have to adjust the center point of the motor speed control.

Looking promising though.

cheers

Tony

**rprosperi** · 09-25-2023, 12:04 PM

(09-25-2023 05:43 AM)teenix Wrote: Hi all,

Slow progress, I have been inundated with offspring requests, I thought by now they would have grown out of that :-)

Are these requests from existing offspring?

If so, I get it - they are priorities, even when they're not priorities...

If not, and these requests are for siring more offspring, why the heck are you writing here???

teenix · 09-25-2023, 09:35 PM

(09-25-2023 12:04 PM)rprosperi Wrote:
(09-25-2023 05:43 AM)teenix Wrote: Hi all,

Slow progress, I have been inundated with offspring requests, I thought by now they would have grown out of that :-)

Are these requests from existing offspring?

If so, I get it - they are priorities, even when they're not priorities...

If not, and these requests are for siring more offspring, why the heck are you writing here???

I see on re-reading the statement, it is somewhat ambiguous. Definitely existing :-)

teenix · (This post was last modified: 09-26-2023 01:36 PM by teenix.)

The processor died on the 19C board:-(

I think it has been reprogrammed too many times and can't take anymore. I guess desoldering it multiple times didn't help. It is a 64 pin beastie so not so easy with home-built tools.

Oh well, onward...

cheers

Tony

pavel nemec cz · 09-26-2023, 06:07 PM

(09-26-2023 01:35 PM)teenix Wrote: The processor died on the 19C board:-(

I think it has been reprogrammed too many times and can't take anymore. I guess desoldering it multiple times didn't help. It is a 64 pin beastie so not so easy with home-built tools.
Oh well, onward...

cheers

Tony

Hi Tony,

It is incredible how you manage overcome your hurdles on personal as well as on technical side. There are folks here ready to express the interest in your progress and superb old HP calculator inner details recreation and documentation. I hope this will help to encourage you to keep going!

Thank you,
KR
P

teenix · 09-26-2023, 10:14 PM

(09-26-2023 06:07 PM)pavel nemec cz Wrote: Hi Tony,

It is incredible how you manage overcome your hurdles on personal as well as on technical side. There are folks here ready to express the interest in your progress and superb old HP calculator inner details recreation and documentation. I hope this will help to encourage you to keep going!

Thank you,
KR
P

That's a nice thought - thank you :-)

cheers

Tony

teenix · (This post was last modified: 10-20-2023 01:05 AM by teenix.)

Hi all,

The 19C hit a snag, so I had to backtrack a bit, but it is moving forward again.

I also put together a Woodstock board. This will support all the Woodstock models but will be pretty much bare bones and won't have many extras apart from Bluetooth, battery-less Continuous Memory and program storage. I have one other thing in mind, I'll see how I go.

Not much more today though, the temp is climbing, and I am living in a slow cooker.

cheers

Tony

tangdfx · 10-20-2023, 04:37 AM

Great news. Revived the Woodstock project.

zixingcheche · 10-20-2023, 05:23 AM

(10-20-2023 01:04 AM)teenix Wrote: Hi all,

The 19C hit a snag, so I had to backtrack a bit, but it is moving forward again.

I also put together a Woodstock board. This will support all the Woodstock models but will be pretty much bare bones and won't have many extras apart from Bluetooth, battery-less Continuous Memory and program storage. I have one other thing in mind, I'll see how I go.

Not much more today though, the temp is climbing, and I am living in a slow cooker.

cheers

Tony

Looking forward to this. Thanks!

teenix · (This post was last modified: 10-21-2023 05:16 AM by teenix.)

Hi all,

A bit cooler today so I was able to do some more on the 19C.

The attached image shows how the new boards assemble. I tried a few different ways to achieve this, but in the end the HP engineers knew what they were doing, and their method seems the best for the overall "clamshell case" design of the calculator.

That meant having to use most of the original board to board connectors so there will be a bit of soldering for this CPU board. It's not that hard to do but if it is too tricky then I can fit them.

Getting there :-)

cheers

Tony