hp 32s repair - dead right column of keys



#3

One day my HP 32s developed exactly the problem described by Tom Brentnall (orig post copied below) - dead right column of keys. I decided to try gently twisting the calculator body back and forth to see if I could restore good contacts at the internal keyboard connector. It worked! Time will tell how long this will last.


orig post========================================================
HP32SII repair
Message #1 Posted by Tom Brentnall on 8 July 2002, 5:12 p.m.

After my second 32SII lost the use of a column of keys, I figured there must be a weakness (probably mechanical) that might be able to be fixed or cleaned.

Since I can't find a new 32SII, I tore my first one apart and made some observations that allowed me to fix my newer one.

This fix may be applicable to you if the following test works: If the right row of keys (+, -, x, etc.) doesn't work, try squeezing the bezel below the display and just above the 1/x or E+ key: gently pinch the back of the calculator to the front of the calculator. If that makes the right row work, there is probably a bad connection between the keyboard and the PCB.

Since I didn't have much luck opening my first unit, I decided to use precision surgery rather than opening my second one. The PCB is fastened using twisted metal tabs. I used a soldering iron to melt open a small (5 mm dia) hole in the back just over the twist tab near where the pressure solved the bad key problem. I then inserted a needle-nose pliers into the hole, twisted the tab a little tighter and the calculator now works like new!

For problems near the right side: the tab is located 97 mm from the bottom and 11 mm in from the edge. There is a tab on the left symetrically located, as well as one in the center.

Use the hot tip to carve the plastic away, and trim any flashing with a flush cutting diagonals. I was going to use a "Moto-Tool" to carve a hole, but was afraid the dust would do additional harm.

My model is one of the newer units with a single sided PCB with no mylar or foil to be concerned with. I only had to twist the tab 1/10 of a turn or so. Too much could break it off. I just twisted the tab a bit and then tested the keys, stopping whe it was enough. I read in your forum where some people had luck using an ultrasonic cleaner, but I don't have one, so I tried this. Also, your case will be stronger when you drop it, if you don't have to cut the plastic rivets and pry it apart.

True, there is a little hole in the back, but I just put a sticky label over it to keep dust out.


#4

Quote:
This fix may be applicable to you if the following test works: If the right row of keys (+, -, x, etc.) doesn't work, try squeezing the bezel below the display and just above the 1/x or E+ key: gently pinch the back of the calculator to the front of the calculator. If that makes the right row work, there is probably a bad connection between the keyboard and the PCB.

Since I didn't have much luck opening my first unit, I decided to use precision surgery rather than opening my second one. The PCB is fastened using twisted metal tabs. I used a soldering iron to melt open a small (5 mm dia) hole in the back just over the twist tab near where the pressure solved the bad key problem. I then inserted a needle-nose pliers into the hole, twisted the tab a little tighter and the calculator now works like new!

For problems near the right side: the tab is located 97 mm from the bottom and 11 mm in from the edge. There is a tab on the left symetrically located, as well as one in the center.

Use the hot tip to carve the plastic away, and trim any flashing with a flush cutting diagonals. I was going to use a "Moto-Tool" to carve a hole, but was afraid the dust would do additional harm.

My model is one of the newer units with a single sided PCB with no mylar or foil to be concerned with. I only had to twist the tab 1/10 of a turn or so. Too much could break it off. I just twisted the tab a bit and then tested the keys, stopping whe it was enough. I read in your forum where some people had luck using an ultrasonic cleaner, but I don't have one, so I tried this. Also, your case will be stronger when you drop it, if you don't have to cut the plastic rivets and pry it apart.

True, there is a little hole in the back, but I just put a sticky label over it to keep dust out.


Another method is to actually open the calculator via the rivet points. There are a total of 8 rivets. If you remove the battery cover, you can see four of them, a pair on each side of the battery compartment. Four more are located toward the bottom of the calculator. What I do is use an exacto knife to loosen these four rivets in the battery compartment. Since they are heat fused, just "cut" the plastic bond along the inside of each rivet hole (do not destroy the rivet itself). Then, using a toenail clipper (flat part) you can pry apart the two halves near the battery compartment (i.e. pop the four rivets from their place). Then, undo the sides (just use the nail clipper). Finally, undo the bottom four rivets with the nail clipper (everything is well protected down there so you won't damage anything).

This method is essentially the same as the one I use to open up an HP48.

How to Open an HP48

The benefit is that your calculator is almost as structurely sound as before, and there are no visible cosmetic marks due to the repair. I've repaired an HP22S that had the exact same problem as you've described, and it looks and feels just like one that had never been opened.


Edited: 19 July 2006, 2:34 p.m.


Possibly Related Threads...
Thread Author Replies Views Last Post
  Broken keys on HP Prime? Tarcisi C 0 303 12-10-2013, 05:59 PM
Last Post: Tarcisi C
  HP 50g switching two keys in the user keyboard Sean Freeman 9 876 12-05-2013, 11:44 AM
Last Post: Mark Puscas
  HP Prime: How do I insert/delete a column/row in a spreadsheet ? Michael de Estrada 3 548 11-20-2013, 10:01 PM
Last Post: Michael de Estrada
  [HP-Prime] off-center [0], ... [9] num keys CompSystems 1 312 10-18-2013, 10:44 PM
Last Post: Han
  HP PRIME: How to change the column headers and reset data Joseph Ec 5 545 10-18-2013, 02:26 PM
Last Post: Joseph Ec
  HP Prime - Home and CAS keys BruceH 0 228 10-15-2013, 07:19 PM
Last Post: BruceH
  HP Prime Tip: Setting Up User Keys Eddie W. Shore 2 374 09-27-2013, 09:53 PM
Last Post: Eddie W. Shore
  Joys of eBay: HP-32S, HP-32SII, HP-42S, HP-16C, ... Sasu Mattila 7 620 09-23-2013, 04:39 PM
Last Post: Julián Miranda (Spain)
  HP 32s LCD part Trisnadi Sutrisno 2 343 08-27-2013, 02:12 PM
Last Post: Han
  [HP-Prime] Lack of user soft keys Andy B (Australia) 1 302 08-17-2013, 11:00 AM
Last Post: Tim Wessman

Forum Jump: