HP Forum Archive 06

[ Return to Index | Top of Index ]

HP-21 Decimal Places Message #1 Posted by Reed Jones on 8 Oct 2001, 1:54 a.m. I just acquired an HP-21 at a garage sale. I replaced the bad cells in the battery pack, and the calculator appears to work fine. (I read everyone's warnings about turning on the calculator without a good battery pack so I didn't make that mistake!) However, I couldn't find an answer in this forum or the archives on how to change the number of decimal places displayed. When the calculator is turned on, only two digits to the right of the decimal point are displayed. Using the DSP key, the calculator goes into scientific mode with the selected number of decimal places. Is there a way to change the number of decimal places on the display without the calculator without going into scientific mode? I also got an HP-25C at this sale, but without battery pack or charger. It appears to work fine with the 21's battery pack when the charged battery pack is partially inserted, but loses contact when fully inserted. Any ideas on how to get good contact here? BTW, my nearly 20-year old 41CV still faithfully serves me daily and I received my $50 HP Top-Secret rebate for a 48G+.

Re: HP-21 Decimal Places Message #2 Posted by Andre' Wilhelmus on 8 Oct 2001, 4:06 a.m., in response to message #1 by Reed Jones Try DSP . digit

Re: HP-21/25C Message #3 Posted by Ion Abraham (New Mexico USA) on 8 Oct 2001, 9:51 a.m., in response to message #1 by Reed Jones Reed and others, I can confirm the display setting solution (DSP period) and as to the contact to the battery pack, well, I can think of two things. Either you need to clean the battery surface contacts, that is, maybe when the battery is inserted all the way it makes contact in a bad spot on the batteries. The other option is that the battery pack was rebuilt badly, and is somewhat thicker now than it used to be. Look at the seam under the back of the pack and see if that looks OK. I also have a question that may be old news for some of you. Is there a list of which part no. charger goes with which calculator? For example, there seem to be two chargers whose connectors fit the 21's and 25's, the 82026 and the 82041, but I don't think they actually ought to be interchanged. Best regards, Ion Abraham Albuquerque, New Mexico P.S. Reed, if you would like to sell trade the 25C for 41C items, I may be interested. You can contact me directly at the indicated email address.

Re: HP-21 battery contacts Message #4 Posted by David Smith on 8 Oct 2001, 3:59 p.m., in response to message #1 by Reed Jones Yes, you should try sanding the contact buttons in the calculator with some fine sandpaper (you dont want to wear them down). The best way I have found to get good contact in stubborn Woodstock and HP19C / HP 10 machines is to take a piece of aluminium foil folded over a couple of times and place it over the battery contacts in the battery holder then insert the battery. Works every time for me.

[ Return to Index | Top of Index ]

Go back to the main exhibit hall