HP Forum Archive 16

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48sx me vs. machine Message #1 Posted by Charlie O. on 23 June 2006, 12:56 p.m. I bought a 48 sx from ebay and have it a couple days. I have spent 2 days trying to do the intro step by step in chapter 1. After 20 or so trys, I have not got the same result twice. Sometimes the calc hangs at step 6 and other times at 26 or in between. When it hangs the only way I have found to get out is the 3 key reset. How can I tell if I am just a total calc klutz or if it is the calc itself? Any help is much appreciated! Thanks, Charlie O.

Re: 48sx me vs. machine Message #2 Posted by Han on 23 June 2006, 3:22 p.m., in response to message #1 by Charlie O. Quote: I bought a 48 sx from ebay and have it a couple days. I have spent 2 days trying to do the intro step by step in chapter 1. After 20 or so trys, I have not got the same result twice. Sometimes the calc hangs at step 6 and other times at 26 or in between. When it hangs the only way I have found to get out is the 3 key reset. How can I tell if I am just a total calc klutz or if it is the calc itself? Any help is much appreciated! Thanks, Charlie O. The fact that the 3-key reset works is usually a good sign that your calculator may be fine. When the HP48SX "hangs" what happens to the screen? And does the calculator beep at all when you try to press the keys during the hang? Here are some self-tests you can try: Press and hold ON, then press D, and finally release both keys to enter the self test mode. (To exit, press and hold ON, then C, then release both). You should see three vertical lines. Press C to do the ROM test. Press D to do the RAM test. If any of these two tests fail, then there may be some hardware problems (in particular, the address lines may be damaged, possibly from corrosion). What I describe below is a worst-case scenario (it has happened to me). But I give you this anecdote anyway =) If there is battery corrosion (you can tell by looking at the terminals of the battery compartment), it is possible some of the corrosion has gotten to a major component. The HP48SX motherboard is not silkscreen, so the traces can easily corrode. The CPU is not encased in a plastic package like the HP48G series CPU. In one of my HP48SX calculators that I bought used on eBay (it has since been taken apart to the point that it cannot be reassembled), the corrosion was not apparent on the terminals. The calculator in fact appeared almost new. However, when I opened up the calculator it was clear that corrosion occured, as some of the traces had green buildup on them. Upon careful inspection, I noticed that one of the pins from the CPU was also corroded, to the point that the green buildup was what kept the pin intact (but destroyed the circuit involving this pin). I am speculating that your calculator may have a similar symptom and that is why there is some inconsistency with the hangups. While things appear normal, even the slightest perterbation may cause a cut circuit causing your hangups. Han Edited: 23 June 2006, 3:23 p.m.

Re: 48sx me vs. machine Message #3 Posted by Charlie O. on 23 June 2006, 6:19 p.m., in response to message #2 by Han Han, Thank you for your help. After I posted, I found the tests in my manual and the calc passed both. The calc did beep after hanging. I only remember a single verticle line down the center of the screen but the light may have been too dim. The battery compartment is clean, no signs of corrosion. When I was trying the examples, sometimes the menu at bottom of display would change. There seemed to be no consistancy from one time to the next. I have tried to teach myself to program and have many hp's but can't seem to grasp. I know I can enter keystrokes but don't know why my results are different than the book. Charlie O.

Re: 48sx me vs. machine Message #4 Posted by Han on 23 June 2006, 7:27 p.m., in response to message #3 by Charlie O. Your results may be different, or the machine may appear to hang due to various flag settings. Try pressing and holding ON, then press A and F and release all three keys to clear the memory. Select NO when you are prompted to recover memory. As you already know, this resets the calculator as well as all system flags. Also, the steps mention using radian mode. If you are doing any sort of symbolic manipulations (some of the steps work through an indefinite integral), your answer will be different if you are not in radian mode. If you are willing, start fresh and tell us when you run into problems. Perhaps we can retrace your steps on our own HP48SX to see if it is indeed a calculator thing. Han

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