82143 adventures



#2

The printer head was sticking in its transit so I decided to open it up for a cleaning.

This simple little task took me nearly 8 hours. I got very good at soldering since I must have broken 25 year old connections inside on several occassions as I manipulated the innards to get at things.

Plus, I had no clue how to properly reassemble it so the printer head could move freely. So it came apart a few more times. And there was more soldering as I broke off more wires. Etc.

But I got to clean what shouldn't be greasy are regrease what should be. And I did sort out how to tuck things out of the way so the print head slides swiftly back and for.

At the end of the day, it works better than before.

But I won't be doing that again soon, sheesh.

Good thing I am not a surgeon....

Les


#3

Quote:
Good thing I am not a surgeon....

Hey, at least you didn't leave a sponge or hemostat inside it.

(Technically it is the responsibility of the scrub nurse to count everything to make sure nothing is left inside the patient.)

#4

Cancel my enthusiasm.

The thing is basically good for parts now.

I think my repeated resoldering of the yellow wires onto the printer mechansism (there is a pair coming off the mainboard) has done some damage by virtue of the heat. Now the motor simply spins briefly when I power up, twists the rubber drive ring around its cam (if it doesn't get thrown off altogether) and the thing doesn't advance, the printer head doesn't move, and it just makes a whining sound. Does this when the yellow wires aren't connected either,so I surmise that when the yellow wires are connected they are not directing the behaviour of the print mechanism in any way.

I think I have damaged the printer mechanism proper and that can't be repaired.


I have done a real number on this thing....

Les

Edited: 27 Feb 2007, 11:52 p.m.


#5

Don't give up so easily...

You can download 'my' schematic for the 82143 from The Australian Site. That'll give you a start, I hope.

The 2 yellow wires go to a switch contact in the mechanism that detects when the printhead is in the 'home' (right hand?) position. IIRC, part of the power-on initialisation is to run the printhead to the home position, detected by that switch. So if there's a problem with it, the motor will run the printhead into the side of the printer.

Take the printer mechanism out and connect an ohmmeter to the 2 yellow wires (unplugged from the logic PCB). See if the switch opens and closes when you turn the leadscrew by hand to move the head back and forth. I _think_ the switch is closed at the home position, but I can't be sure.

Alas if that all seems OK, then the most likely problem is the microcontroller, which is custom-programmed for the 82143. But most 82143s seem to die from printhead problems, so finding a parts unit with a good microcontroller might not be too hard.


#6

Frankly, Tony, I have learned I have no facility with microelectronics repair and really should've left well enough alone.

I have sunk many frustrated hours into this mess and I do not have the engineer's tenacity when it comes to fixing things.

I did pay just $50 for the printer (plus shipping which in retrospect was a bit excessive), and did get a few months pleasure out of it, so I would like to chalk this up to a learning experience and pass it on to someone who can get some good out of it. I have already had inquiries from folks who will take it for parts. Frankly, I just want to get rid of it and if I need to print something I always have the 82240 which works beautifully (I also have the IR module for the 41C). Looking at it as a testimony to my ineptitude is a little painful.

many thanks,

Les


#7

Actually, I can really get to like the IR printer.

It is a bit slower, but I like the font a lot better.

It also works with 6 of my calculators (41CV, 41CX, 42S, 48G, 49G+, 17bii+).

Maybe one day I will replace the murdered 82143. But I need time. Sort of like that feeling one has after a beloved bet has died.

If I don't firm up any arrangements for this thing for parts in the next couple of days I will place an ad in our Classifieds.

Les

#8

Try turning the drive wheel by hand. If the head is moving freely your problem is just an old drive band. Projector Recorder Belt Company model SCX2.4 (or is it 2.3?) works well. It is a square profile belt, but works fine. Standard .062" round o-rings are too fat.

#9

Just wanted to report that our inimitable friend Randy was able to repair my mess very quickly and inexpensively.

Looks like previous repair attempts had led to a wrong size o-ring replacement, among other things. I would've spent eternity trying to reverse the problems with the tools and parts I had on hand.

Three cheers for the near-saintly FixThatCalc.com!!!

Les

Edited: 13 Mar 2007, 9:26 a.m.


Possibly Related Threads...
Thread Author Replies Views Last Post
  82143 Printer Service manual gileno 4 328 08-10-2008, 07:39 PM
Last Post: Eric Smith
  82143 Printer Cable for HP41 for I/O Philip 2 245 12-04-2005, 06:12 PM
Last Post: Philip
  82143 Batteries Thomas Caphorn 3 286 07-29-2004, 04:40 PM
Last Post: David Smith
  Question about 82143 printer battery pack Jim Creybohm 3 339 01-07-2004, 06:37 PM
Last Post: Tom Sherman
  Thermal Printer 82143 -Problems to operate the printer- Martin Wahlich 4 415 12-07-2002, 04:01 PM
Last Post: Martin Wahlich
  HP 82143 protocol Vassilis Prevelakis 1 228 07-06-2002, 06:16 PM
Last Post: Tony Duell (UK)

Forum Jump: