Opening up a 32E



#2

Hello all!

I just received a HP32E in great cosmetic condition. However, it suffered the dreaded 'battery pack leakage'. I cleaned up the battery contacts but if I put in a known good battery pack the calculator will not turn on. I figure I have nothing to lose and want to open it up to see the extent of damage the leaking caused. I am able to remove the two screws in the battery compartment but the calculator is still held together by something along the bottom edge. Viewing some of the 'exploded' 30-series calculator views on this website I get the impression the bottom edge is not held together by screws but is somehow staked or slip-fitted. Is there a trick to getting the two halves apart? Thanks in advance!

Brian


#3

When I first had to open my HP-34C I tried a couple of methods. This is the one that worked:

http://voidware.com/calcs/spicerepair.htm

Thank Hugh Steers for that tip :-)

Regards,

Gerson.


#4

Yes, that method works... to rip the flex circuit of the battery connector right off the terminal board... when the case snaps free.

A simple precaution is all that is needed to prevent damage. The top right photo shows the back being removed with the unit face down. That's fine but: you must lift the top of the case back off the battery connector board before applying pressure to disengage the bottom latch. Again, pull the case bottom away from the battery connector leaving the connector attached to the front of the case. Once it is free, then apply pressure downward to disengage the latch. You need a fair amount of force to snap it free, once it lets go, that energy goes into pulling the board out of its slot and tearing the flex circuit is collateral damage.

Also, fifth row down, left photo: NEVER SCRAPE THE CONTACTS or you'll be looking for a replacement keyboard. Clean well with isopropyl alcohol, clean the spring contact and re-lube lightly with a good white grease with teflon.


#5

Quote:
Yes, that method works... to rip the flex circuit of the battery connector right off the terminal board... when the case snaps free.

Well, I opened also a 33C using that method and I never had the flex circuit damaged. Either I was lucky or somehow I was careful enough. Anyway, thanks for calling our attention on this.

I opened them to change the decimal point to comma. I have another 33C which I never opened. One of these days it got me confused with a positive answer that was supposed to be negative. When I remembered to check the minus sign I noticed the minus segment was not working. I then let it fall from a one-inch height and it started working again. This was made in Brazil for local market, so the decimal point has been factory set to comma, therefore I didn't have to open it. But I am worried if I ever have to open it, as it is a solderless unit.

Regards,

Gerson.

#6

Greetings, Brian --

Quote:
Viewing some of the 'exploded' 30-series calculator views on this website I get the impression the bottom edge is not held together by screws but is somehow staked or slip-fitted. Is there a trick to getting the two halves apart? Thanks in advance!

Not knowing exactly where and how to squeeze the case halves to separate them, I devised this "dental floss" method several years ago, using it thrice on two Spices with no damage:

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv009.cgi?read=22660

-- KS

Edited: 24 June 2007, 9:12 p.m.


#7

Greetings Brian,

I have successfully opened up my 33E twice using the voidware - spice repair technique mentioned above. It is true that you have to be a little cautious with the battery contact but the method works well.

I did try Karls' dental floss method but the floss I used may have been too flimsy as it kept breaking. Maybe you need heavy duty dental tape...

In any event, opening a spice should not be a big deal - especially if you have read the above posts. Good luck.

Jeff


#8

i'd like to say that the credit for this technique goes to Tony Duell, who demonstrated this to me. i just made some pictures to help others.

glad that it has helped!

also,

i'd agree with the warning of never scraping the circuit board. in my case, i lightly scraped the back of the spring switch contact that had picked up a crust of corrosion of the years. the spring is all metal.


Edited: 25 June 2007, 4:50 a.m.

#9

Thanks to all who responded! I did manage to get the case apart with no apparent damage and cleaned up everything inside, then reassembled. Unfortunately the problem did not get solved.

With a new battery pack installed, if I switch the calculator from 'Off' to 'On' there is no response. However, when I slide the switch back to 'Off' at about the mid-point between 'Off' and 'On' one of the LED segments in the upper left hand corner of the LED window glows faintly then fades out. This is the same behavior the calculator exhibited before I opened it up. I suspect corrosion got to the ribbon connector between the battery connectors and the circuit board but the traces still look good.

Anyone have any ideas?

#10

You wrote:

Quote:

... I just received a HP32E in great cosmetic condition. However, it suffered the dreaded 'battery pack leakage'.


What is interesting about all of the leakage problems is that there was a time back in 1972 when designers at both HP and TI understood that there was a potential problem with circuit damage from cell leakage and did something to prevent it.

You can see it in the HP product line in the Classic family where the assembled case provides a box around the battery pack. There was some of that in the Woodstock family. Any pretense of isolating the battery pack from the circuitry went out the window with the Spice family and the HP-41.

You can also see it in the TI product line in the Datamath machines. I recently purchased a TI-2500 (1972) -- the version with the six rechargeable batteries accessible through a trap door. I didn't have my Phillips head screwdriver with me but the device ran perfectly with the Adapter/Charger. I reasoned that there must not be any circuit damage from leakage so I bought it for a dollar. When I opened the trap door I found massive cell leakage. When I opened the calculator there was no circuit damage and I could see why. The case essentially formed a bathtub to enclose the cells and isolate any leakage from the circuitry. Any pretense of isolating the battery pack from the circuitry went out the window with the TI-30, TI-1XXX's, and the TI-5X's.

If the designers of the early machines at HP and at TI understood the need to isolate the circuity from cell leakage then why did the later designers abandon the concept? Did they begin to believe the claims of the cell manufacturers for their "sealed" cells? Did they decide that since the cell manufacturers were offering to repair devices damaged by cell leakage then the user would suffer no economic damage from cell leakage? Any ideas out there?


#11

Quote:
Any pretense of isolating the battery pack from the circuitry went out the window with the Spice family and the HP-41.

It must have continued at least a bit longer, into the Voyager family. I never noticed it until a few years ago, when my beloved 16C suffered a leaking battery. I was horrified to see all that gunk in the battery compartment, but while cleaning it out I discovered that the batteries were surrounded by a "bathtub" arrangement such as you described above. The only metal bits which any of the chemicals were able to reach were the two battery contacts, which are spring clips that hang over the top edge at opposite ends of the "tub." A little careful cleaning with a brush dipped in white vinegar made them good as new. (I just now opened it up to check them, and they're still bright and shiny.) None of the corrosion made it out of the battery compartment itself, and my 25-year-old HP-16C continues to work as well as the day I bought it.


#12

Quote:


It must have continued at least a bit longer, into the Voyager family. I never noticed it until a few years ago, when my beloved 16C suffered a leaking battery. I was horrified to see all that gunk in the battery compartment, but while cleaning it out I discovered that the batteries were surrounded by a "bathtub" arrangement such as you described above. The only metal bits which any of the chemicals were able to reach were the two battery contacts, which are spring clips that hang over the top edge at opposite ends of the "tub." A little careful cleaning with a brush dipped in white vinegar made them good as new. (I just now opened it up to check them, and they're still bright and shiny.) None of the corrosion made it out of the battery compartment itself, and my 25-year-old HP-16C continues to work as well as the day I bought it.


The only Voyager that I have here in North Carolina is a USA made HP-12C S/N 2636A64325 . There is a small possible path past the tab portion of the battery cover. How much leakage could get through would depend on how closely the tab fits into the slot which does appear to be a relatively close fit. I can see printed circuitry through the slot. In any case, a much better arrangement than the Spice family and the HP-41 since my experience suggests that somehow the leakage from a cell can tend to follow an electrical lead.

I have a HP-28S "Clamshell" here. I'm not going to fiddle with the world's worst battery cover design because I fear I may lose all my data.

I also have a representative of the Pioneers -- an HP-10B. It has a path for leakage out of the battery bathtub through the opening for the tab which is over twice as wide as the tab. Again, I can see printed circuitry through the opening.


Possibly Related Threads...
Thread Author Replies Views Last Post
  opening hp 15c for repair FORTIN Pascal 4 680 10-12-2013, 10:35 AM
Last Post: FORTIN Pascal
  HP45/32E Connection Matt Agajanian 2 472 07-07-2012, 06:31 PM
Last Post: Matt Agajanian
  32E's Normal & Inverse Normal Distribution Matt Agajanian 27 2,166 04-14-2012, 06:07 PM
Last Post: Dieter
  Bedtime for the 32E Matt Agajanian 10 1,059 04-07-2012, 05:57 PM
Last Post: Luiz C. Vieira (Brazil)
  Changing radix mark on a 32E Matt Agajanian 8 882 04-07-2012, 04:59 PM
Last Post: Walter B
  Does this HP-32E from eBay sound legit? Matt Agajanian 4 565 03-28-2012, 03:00 PM
Last Post: Lincoln R.
  21, 45, 32E--which should be next? Matt Agajanian 14 1,345 03-25-2012, 02:48 AM
Last Post: Thomas Radtke
  HP-32E missing digit Matt Agajanian 11 1,081 03-21-2012, 11:08 PM
Last Post: Luiz C. Vieira (Brazil)
  opening HP 30B Harald 6 705 02-26-2012, 09:07 AM
Last Post: Marcus von Cube, Germany
  Opening a 100LX David Ramsey 4 535 11-29-2011, 12:34 PM
Last Post: Hubert Weikert

Forum Jump: