Still looking for HP-41C/CV/CX HalfNut Schematics

[rocket.scientist]

My google-fu is failing me. I have been searching high and low for schematics for the halfnut version of the HP-41C/CV/CX. I have found any number of "look here" leads, but none have resulted in a schematic. On this forum I have the latest thumb drive and paged through the following documents:

41sm.pdf (tantalizingly close, but no halfnut schematics)
p41srvc.pdf
41schem.pdf (beautiful piece of work here. Clear and concise. Not halfnut.)
hp41cpu.pdf
41addics.pdf
41csm.pdf

Anyone have another place to look? A working link with page-specific guidance would be greatly appreciated.

Thanks!

-Pat (KG5YPQ)

[Raymond Del Tondo]

Did you look at TOS?

They have a list of documents available there.

[rprosperi]

(07-13-2020 10:47 PM)Raymond Del Tondo Wrote:  Did you look at TOS?

They have a list of documents available there.

He/she is new here, and despite being a rocket scientist, it's likely TOS isn't clear.

This is a website that specializes in the HP-41, but it's impossible to simply place the url here (ancient history).

Basically it's http://www.coconut.org, where you insert "HP41" where coconut is seen.

Click on the "Library" on the left and there's a lot of stuff to look through.

Good luck!

[rocket.scientist]

Thank you for your considered replies. While true that I am new to this forum, I have done some research before asking. Including at that other site. :-)

I did find a number of documents that were all around the Hp-41, on the publications both here and there. I was not able to find a schematic for the halfnut anywhere. Admittedly some of the scan quality was less than ideal and many documents had not been run through OCR. After a few thousand pages, my eyes were getting pretty bleary.

I do have recent thumb drives from here, as well as the PPC archives. I have also found other resources and collections, including the Section VII Addendum to the HP41C/CV/CX Service Manual (00041-90472). There were lots of fullnut schematics for many production version. Sadly there are no halfnut schematics to be found.

I am hoping someone here has seen what I have missed, and can provide a definitive lead. Let me know if something needs to be pursued off-list.

For now and for me, a document with halfnut schematics remains hearsay.

Kindest regards,

-Pat (KG5YPQ)

[HP67]

(07-14-2020 01:51 AM)rprosperi Wrote:  

(07-13-2020 10:47 PM)Raymond Del Tondo Wrote:  Did you look at TOS?

They have a list of documents available there.

He/she is new here, and despite being a rocket scientist, it's likely TOS isn't clear.

This is a website that specializes in the HP-41, but it's impossible to simply place the url here (ancient history).

Basically it's http://www.coconut.org, where you insert "HP41" where coconut is seen.

Click on the "Library" on the left and there's a lot of stuff to look through.

Good luck!

Hah! When I see guys write TOS I thought they meant ebay or *maybe* hpcalc

I learned something, thank you Bob! My day is no longer a loss!

[Sylvain Cote]

(07-14-2020 02:39 PM)HP67 Wrote:  Hah! When I see guys write TOS I thought they meant ebay ...

That one is called TAS (The Auction Site), but eBay now seems to be permitted, not so for TOS (The Other Site).

[rocket.scientist]

So I have looked in the recommended places, purchased the latest thumb drives and other media, and downloaded gigs of data. The closest I have found to the elusive halfnut schematic is the Section VII Addendum to the HP41C/CV/CX service manual. The index for the addendum claims the schematics are on pages 7-17 - 7-19. The scan ends at page 7-12. (Well, there is a reversed calculator assembly page . . .)

*grumble*

Anyone else get further than this? I feel like I am chasing phantoms.

-Pat (KG5YPQ)

[cruff]

In this thread HP 41C data storage integrated circuit swapping: Maybe Eric could answer this ;-), message #8, Ignazio Cara mentions an addendum 00041-90542 that may contain the information you are searching for. He stated he was trying to get that information to Dave for inclusion on the MoHPC DVDs. Perhaps if you try contacting him to see what came of this?

[rocket.scientist]

Interesting. The appendix I mentioned ("Section VII Addendum to the HP41C/CV/CX service manual (00041-90472)" is marked with a reorder number of 00041-90542. The halfnut schematics seem almost surgically removed from the copies of 90472 I have found. I wonder if this omission was done by error in the 90472 document, but present in the 90542 version.

A mystery is afoot! I will see if I can find Ignazio. Thank you for this most excellent lead.

-Pat (KG5YPQ)

[rocket.scientist]

Here is where I am in this search. I have reached out to a couple of the principals identified in the "HP 41C data storage integrated circuit swapping" thread above. There have been no responses yet, but I remain hopeful. On the knowledge already in the archives, I have identified 3 cases that appear to describe the 00041-90472 / 00041-90542 documents already out there. Note in all 3 cases, the first page of the PDF is full color with a blue cover sheet marked by HP appropriately. This is based on finding this document at 6 different sites, some common, some not so common.

Case 1: The base document 00041-90472 does not contain Appendix VII "HP-41 Halfnut Construction", which is where the halfnut schematics are reputed to appear.

Case 2: The base document does contain Appendix VII, and the following pages are a series of alternating good pages and blurry "scanned through the page" reversed pages. The TOC for Appendix VII cites schematics for the various halfnuts are in Figures 7-9, 10 and 11 (pages 7-15 thru 19). This version of the scan ends at page 7-12, and usually has a reversed blurry "through the page" scan of Figure 7-12 (page 7-21), the HP-41 Exploded view. The schematics are missing. This version was produced with sspdflib 1.0 (ScanSoft).

Case 3: The base document does contain Appendix VII, and the following pages are all clearly scanned and consecutive. Again the TOC for Appendix VII cites schematics for the various halfnuts are in Figures 7-9, 10 and 11 (pages 7-15 thru 19). This version of the scan ends at page 7-12. This is the end of the scanned document and the schematics are missing. This version was scanned in 2012 and produced with AFPL Ghostscript 8.11.

Every time I find this document one of the three conditions above apply. So far my conclusion is that the halfnut schematics are missing, perhaps deliberately, from accessible HP-41 archives. It may also be that the schematics were printed landscape, and the original scanners did not go back and include them.

If someone has this document with a complete Appendix VII, or if you run across a complete scanned version somewhere online, please consider sharing it with the community.

Regards,

-Pat (KG5YPQ)

[GreyUser]

I have an original dvd from the TOS, the image on my disk is a combination of 1 & 2 in your post. Appendix VII is not in the index but the section is in the scan without the schematics.

I would be willing to bet the schematic never made it into general distribution as HP considered it a non-repairable assembly, it was replacement only so there was no need for the schematic to be in the public domain. The only differences between the models was the CX clock module, where the extended memory resides and the two different LCD driver modules due to the memory size differences of the CX/CV and the C.

Other than those bits of information, it’s probably a very dull and boring schematic. There’s not much there that cannot be gleaned from the available schematics.

Personally, I’ve never seen a schematic and I’ve never needed one to repair a unit, at least to the extent a halfnut can be repaired.

Why the search? What do you need/want to know?

[rocket.scientist]

I have a few HP-41s, both fullnut and halfnut. All being HP, I have an affinity for both versions. It bothers me that I know so little about the design of the Halfnuts. I guess I have always been motivated more by things I know I do not know, than things I do. It is an unquenchable thirst for knowledge.

I definitely agree the schematics have been missing from the community for a long time. Looking at the metadata and fingerprints in the available PDFs, it is clear they were scanned from paper almost a decade ago, if not longer. Looking closely at the PDFs, there are indications the schematics were present in the paper version. Para7-41 states "The schematics for the Halfnut HP-41C/CV/CX are shown in figures 7-9, 7-10 and 7-11, respectively. They are provided for information only since the alarm is the only replaceable discrete component." Further, for PDF versions with the poorly scanned final page, it is clear it is the HP-41 Exploded View, and you can just make out it is on page 7-21. That leaves pages 7-13 thru 7-20 missing.

I know I am not as knowledgeable as most of my fellows here, so it surprises me a bit that I am one of a very few to note this discrepancy. As you point out, it may not matter to most. These Halfnuts are not designed to be field serviceable, and only minimally so at the factory. I see it as a gap in my knowledge, and a potential impediment to my ability as a hobbyist seeking to preserving these devices. I prefer to believe the schematics are present in the paper version of the document, and that someone in this forum has a copy. One day they will surface and we can add them to this wonderful collection.

Thanks to everyone for the ideas and suggestions. I'll leave this thread alone unless something new turns up.

Kindest Regards,

-Pat (KG5YPQ)

[ignazio]

Hi Pat,
I've checked on my docs and I've found the 00041-90542 Addendum to the HP 41C/CV/CX manual 00041-90472 that end with the following page. Sorry, I can't help you further.

Regards

[rocket.scientist]

Thank you for the follow up, Ignazio. If you don't have it, I doubt anyone will.

Regards,

-Pat (KG5YPQ)

(07-17-2020 05:11 PM)ignazio Wrote:  Hi Pat,
I've checked on my docs and I've found the 00041-90542 Addendum to the HP 41C/CV/CX manual 00041-90472 that end with the following page. Sorry, I can't help you further.

Regards

[HP67]

(07-14-2020 05:23 PM)Sylvain Cote Wrote:  

(07-14-2020 02:39 PM)HP67 Wrote:  Hah! When I see guys write TOS I thought they meant ebay ...

That one is called TAS (The Auction Site), but eBay now seems to be permitted, not so for TOS (The Other Site).

Thank you, Sylvain

[twoweims]

(07-14-2020 05:23 PM)Sylvain Cote Wrote:  but eBay now seems to be permitted,

Not just permitted but required.
I am just now able to sit down after the whoopin' I got for mentioning the unmentionable three letter word a few weeks ago.