HP 42S

[Ted]

I need to replace my HP 42S which I have destroyed with soda. Can it be repaired? If not, I would like to buy one.

[db (martinez, ca.)]

you and about half the people who visit this site would like to buy a 42 (not me; i sold mine when it forgot about 6 k of programs). you will probably get a lot of good advice on what to try to resurect your calcer. you've stumbled onto the den of experts. however, if it cannot be brought back to life, please don't throw it away. you can sell the dead body on this site to somebody who needs parts to fix his/hers. we need to keep the maximum number of these things alive and until the star trek replicator is invented we must all do our part. good luck.

[John Ioannidis]

The 42S is moderately easy to find on e-bay. There is one being offered right now, Item # 1253575253.

There are a lot more 41C/CV/CXs being sold, and they appear to be in high demand, too.

/ji

[Michael Robinson]

If you exercise patience and persistence, you can get a
nice HP-42S on eBay for considerably less than $200. It
may not be new out of the box but it will work fine.

[Tony Duell]

The HP42S (like most modern HP calculators) is not made to be repaired, and opening it is somewhat tricky. Since it's already been soaked, I don't
think that washing it in distilled water will do any more damage.
Take out the batteries, and wash the machine (assembled) in distilled water. When you think you've got all the gunk out, then let it dry and wash it again with
propan-2-ol. Let that dry as well, then put the batteries in again and see if it works. If it doesn't, you'll have to take it a part. Remove the batteries. Peel off the metal overlay on the keyboard (I find it best to work a thin screwdriver under it, between the rows of keys). Do not bend or kink the overlay.
Now drill the tops off the heat-staked studs holding the machine together. 4 under the battery cover, 4 at the front edge of the keyboard on top. Use a 3mm (or 1/8") drill bit held in your fingers or a large pin chuck. Don't use any form of hand or electric drill.
Then pull the back cover off. Twist the tabs and take off the PCB. Clean the gunge off the PCB with distilled water and propan-2-ol. Look for corroded solder joints and PCB tracks, and repair any damage. Clean the contact pads on the PCB with propan-2-ol. Put the PCB back in place and twist the tabs to lock it.
Try it again (put the batteries back in, of course). If it works. put the case back together (often a 42S will stay clipped together without re-staking the posts, which makes future repairs easier).
If it still doesn't work, you probably need to find another machine and also find somebody who can use the parts of your old one.

[David Smith]

If you have access to an ultrasonic cleaner it is worth giving it a good buzzing. Some really powerful industrial type machines might damage the LCD... but then it's already damaged. Try the distilled water rinse first, I recommend a three step bath, changing the water between rinses. Same for the ultrasound treatment. To dry the machine place it overnight (or even a weekend) in an oven on low (say 150 degrees F max) with the battery compartement open.

[Paul Brogger]

I've taken about 10 Pioneers apart and NEVER have peeled away the front foil overlay. See my article in the museum under "Repairs and Batteries/Pioneer Repairs"
( www.hpmuseum.org/guest/brogpion.htm ) for details.