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HP-46 printer - Printable Version

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HP-46 printer - Ignacio Sánchez - 11-12-2012

Dear friends,

I am trying to repair an HP46 op.1 calculator. Seems that the printer is burned because it is blocked ad some smoke comes out when it tries to roll. The thing is that I can get a Compucorp Model 325 "Alpha Scientist" for parts, that aparently sports the same printer model. My doubt is if the characters set of the drum is the same, because externally they look the same (in the photos).
Can you give me your opinion? Do you know if they are the same models and can be used in the hp46?

Many thanks.


Re: HP-46 printer - Katie Wasserman - 11-12-2012

I have these two machines and will check to see if they use the exact same printer (it will take me a few of days before I can get to that). I sure hope that you're not planning on sacrificing a good Compucorp 325 for this HP-46 repair.

Edited: 12 Nov 2012, 12:30 p.m.

Re: HP-46 printer - David Ramsey - 11-12-2012

Katie, what would be your off-the-cuff diagnosis for an HP-46 printer than randomly but consistently fails to print certain positions?

In other words, given a number '1234567890', it will virtually never print the entire number, but which digit positions are missing will vary, although some positions definitely print less frequently than others.

FWIW, replacing that giant capacitor did not help.

Re: HP-46 printer - Paul Berger (Canada) - 11-12-2012

I just happened to notice on ebay what looks like a very similar printer to the one in the 46. http://www.ebay.ca/itm/Vintage-Epson-Model-102-Printer-Calculator-Adding-Machine-Receipt-/281022017319?pt=US_Vintage_Computing_Parts_Accessories&hash=item416e37af27 that may be of interest. I have only seen pictures of the printer in a HP-46 so do not know for sure if it is the same mechanism.

Re: HP-46 printer - Katie Wasserman - 11-13-2012

This condition is covered in the 46 printer repair manual on the Museum DVD. The document is called 46urep.pdf and suggests several mechanical possibilities and a couple of electrical ones. The electrical ones are a bad input trigger pulse due to a loose wire or a problem in the pulse driver circuit. If you have an oscilloscope they suggest looking at the pulse, it should be 15 volts and more than 17.5ms but they don't give any more details.

Edited: 13 Nov 2012, 5:14 p.m.

Re: HP-46 printer - Ignacio Sánchez - 11-13-2012

Many Thanks Katie...you are always there!

No, for sure I will not sacrify this Compucorp...it is non-working and would be for spare parts.

I am nearly 100% sure now that the chars set is different (I have seen it in the Datamath website)...so, probably the question now is: Can I replace the drum in the Compucorp 325 printer for the 46 drum, and install it in the 46?...

I have always heard that monroe 1330, and Busicom 141pf sport the same model...but for sure have different set of chars...as these are not scientific models.

Re: HP-46 printer - Ignacio Sánchez - 11-13-2012

Please look here,:

a similar problem caused by a capacitor:

all the schematics in detail for the hp46:http://www.hpmuseum.net/capcha/freecap_wrap.php?r=2066

Good luck!


Re: HP-46 printer - Ignacio Sánchez - 11-13-2012

Thanks for the info.
Looking at the photos in detail, the set of characters is different, despite the model looks the same.

Many thanks again


Re: HP-46 printer - Katie Wasserman - 11-13-2012

HP has different part numbers for this printer in the 46, 81 and 9805 so surely the character sets are different and it's pretty unlikely that the Compucorp 325 and the HP-46 would use the same character sets. It would be interesting to know if you can move the drum from one to the other and get it to work.

Re: HP-46 printer - David Ramsey - 11-13-2012

I've already replaced the capacitor, so hopefully it's something mechanical.

Re: HP-46 printer - Ignacio Sánchez - 11-14-2012

This is my next challenge! I shall report the results.

Thanks to all for your interest.

Kind regards