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HP Forum Archive 08

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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.

Re: HP32SII repair
Message #2 Posted by Randy Sloyer on 9 July 2002, 9:38 p.m.,
in response to message #1 by Tom Brentnall

Another original repair idea! Glad it worked for you, Tom.

I would be interested to know what went wrong with the opening of the first unit. Cut fingers? Warped / bent case back? Drill the top stakes too deep?

As for the ultrasonic method, this works for when the keyboard has been flooded with the beverage of your choice. Liquefied sugar, cream and even mud and come to mind as common killers of the keyboard. It may have fixed your problem by way of the mechanical vibration reseating the PCB to keyboard flex circuit but I wouldn't count on it.

If the problem reoccurs, I would recommend replacing the foam pressure pad under the flex circuit of the keyboard. Changing the pressure on the connector by way of hold down tabs works but the foam looses it "spring" over time.

You took the right approach. Surgery is most successful when the diagnosis is correct. Good work, doctor.

Re: HP32SII repair
Message #3 Posted by W. Bruce Maguire II on 9 July 2002, 10:43 p.m.,
in response to message #1 by Tom Brentnall


Excellent instructional post. This is exactly the kind of information that should be posted to the Articles section of the Museum for posterity! Could you please post it there?


Are you a king or smth?
Message #4 Posted by W. Bruce Maguire III on 10 July 2002, 4:10 a.m.,
in response to message #3 by W. Bruce Maguire II


Re: HP32SII repair
Message #5 Posted by Geoff Garner on 24 July 2002, 12:11 a.m.,
in response to message #1 by Tom Brentnall

I have a related question pertaining to an HP 42S that I recently purchased (used); however, the issue relates to the case and could pertain equally to the 32SII.

I find that the top part of the brown bezel of my 42S (the part of the bezel that has the 42S and the words "RPN SCIENTITIC") tends to pop up slightly; i.e., it comes away from the case at the top. When it pops up, there is perhaps between 1/32 and 1/16 inch of space between the bezel and the top surface of the calculator. If I push it down, it stays down for a few minutes and then pops up again; it is as if whatever adhesive is holding the bezel to the case is no longer effective near the top (if indeed there is adhesive).

I am curious as to whether anyone else has experienced this problem, either with a 42S, 32S, or 32SII (it seems that the issue is relevant for all 3 calculators as they all have the same type of bezel, apparently attached in the same way. If so, how was the problem addressed? Is a possible fix to simply apply a small amount of glue or cement to the underside of the bezel? If so, are there any precautions that must be taken; e.g., to apply glue under the bezel, it would be necessary to bend the bezel up slightly, but I would not want to risk bending it so much that it breaks off. In addition, what would be the best type of cement to use? If I do glue it, would there be any side effects later, e.g., would the ability to open the case in the future, if necessary, be affected? Any experience that anyone has had with this issue would be helpful.

Thanks. Geoff Garner

Re: HP32SII repair
Message #6 Posted by Randy Sloyer on 24 July 2002, 9:13 p.m.,
in response to message #5 by Geoff Garner

My 10+ year 42S did the very same thing (well, almost). While it was only the corners that came loose, it was most annoying as they rubbed on the case most noticeably upon removal. Eventually, I gave up on trying to stick the corners back down and the brown wore away to the bare aluminum. I never got up the courage to glue them down until... it died one day and required major surgery. With the help and support of the great people here, I cracked open my 42S and was able to repair it. What I learned about the bezel problem was this:

It is attached to the plastic frame with a thin, double sided adhesive film. Over time, the adhesive looses it tack and the bezel pops up. Especially if it has seen any direct stress. My unit took a lot of abuse in my briefcase because I always seem to carry more stuff than the case was designed for. So I was always squeezing the bezel through the slip case. The formed shape of the display window bezel pushes the stress out to the corners and given enough time, things loosen. Or perhaps yours has been cleaned with something the adhesive didn't like. Don't know for sure, but I do know that after disassembling the unit, the top part of the bezel has less than 1/4" of stick-em across the top that holds it down. When you look at the top horizontal line of the bezel, the first 3/16" of metal beginning at the LCD is totally unsupported. Very small surface area with a high stress.

If you want to glue it back down, no problem. I would recommend a small amount of 2 part 5 minute epoxy. You can use a hair dryer and warm the double sided adhesive film to soften it if you can't get under the bezel all the way across the top. You should be able to pop up any area still stuck down, just don't use any force. A wooden toothpick is about the biggest pry-bar I would use. Use another toothpick and force a small amount of mixed epoxy under the metal all the way across the top. Working across, push the bezel down with your finger, let it relax and then clean up and excess with a paper towel and a clean toothpick to clean the groove between the bezel and case. You'll need very little epoxy to do the job. When all the excess has been cleaned up, hit it with the hair dryer again for 15 seconds or so to accelerate the cure. Then just use your fingers to keep pressing it down until the epoxy grips. Worked for me.

I would advise against any "super glue" type products as they all outgas on curing and they leave behind a permanent white film. Most ugly against the brown case. It's also too easy to stick your finger to the bezel...

Some of the others here have used a "shoe goo" rubbery stick-em for this kind of repair, but I have not tried it. Perhaps someone else may share their experiences.

Re: HP32SII repair
Message #7 Posted by David Smith on 25 July 2002, 12:30 p.m.,
in response to message #5 by Geoff Garner

I think that the HP labels pop up on the corners where they were handled by the person installing them and left finger oil on the adhesive. Over the years the oil caused the adhesive to loose tack. The front label on the classics pop up about 90% of the time on the right end and 10% on the left end (but never on both ends)... about the same percentage as right versus left handed assemblers.

Re: HP32SII repair
Message #8 Posted by Raymond Hellstern (Germany) on 25 July 2002, 12:57 p.m.,
in response to message #5 by Geoff Garner

This seems to be quite normal. I've many different Pioneer models, and especially the higher priced ones (w/two lines display) have this 'feature'.

Most of the 'cheaper' models (10B to 14B) don't seem to loose contact that much;-)

My first 42S (Made in USA) doesn't have the problem, all other 42S's have it.


Re: HP32SII repair
Message #9 Posted by Randy Sloyer on 25 July 2002, 1:37 p.m.,
in response to message #8 by Raymond Hellstern (Germany)

Wow Dave, right hand hand vrs left hand! Never would I have thought of that one!.

As for Raymond's comment about the 10/14/20/30 models, I agree that they don't loosen for a very good reason - the bezel is larger on those models. When Hp made the eccono-mode pioneers, they dispensed with the seperately applied Hp logo and increased the height of the bezel and just printed the logo on the top of bezel. The net effect was to increase the surface area of the adhesive.

Re: HP32SII repair
Message #10 Posted by David Smith on 25 July 2002, 6:05 p.m.,
in response to message #9 by Randy Sloyer

I was scrapping out a really gross HP45 and noticed that the front label was lifting on one corner (as most of them are now doing). When I fully removed the label I could see the pattern of a finger print in the adhesive where it was lifting. A little more detective work (and keeping track of a bunch of machines) seemed to have solved the mystery of why one end of the front label of HP machines seems to not stick down... and 9 out of 10 times it's the right side that is lifting. I assume the same thing applies to the other HP labels, but since they have more surface area don't exhibit the problem as clearly.

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