HP Forum Archive 12

[ Return to Index | Top of Index ]

HP-45 problem Message #1 Posted by Michel Beaulieu on 24 Apr 2003, 12:24 p.m. Hi, i have a strange problem on my HP-45 : if i push in a number, only the last on apper on the LCD. If i pus the number 258, the 5 erase the 2 and the 8 erase the 5. I can do some calculation on this one digit number like 1 ENTER, 3 and divide them i get .33333. If i make factorial of 5 i get 120 so ok. But if i make SIN, TAN or COS, the diaplay get blank and never come back until i get the calculator off-on. LN and ex are doing the same. All other math calculations are ok on the digit i enter or the multi digit i get from a previous answer (like 1 Enter 9 + and 1/x i get good answer) Can this problem be fix of it is it a bad/dead obsolete chip? Thanks for help me again with hardware problems...

Re: HP-45 problem Message #2 Posted by David Smith on 24 Apr 2003, 5:32 p.m., in response to message #1 by Michel Beaulieu Most likely cause is a bad ROM chip. Then a bad CPU chip.

Re: HP-45 problem Message #3 Posted by Renato on 24 Apr 2003, 6:38 p.m., in response to message #2 by David Smith Could this be a stuck key ?

Re: HP-45 problem Message #4 Posted by Michel Beaulieu on 24 Apr 2003, 6:57 p.m., in response to message #3 by Renato I try a "motherboard" from a good working HP-45 and the calculator works great so the problem is on the board that have a lot of gold on it... Is there a known problem i can solve on that board? I looked all the connection and they look ok. I cheked all diodes and they are ok. There are a lot of golden chips on the board, what are they for? Thanks

Re: HP-45 problem Message #5 Posted by Tony Duell (UK) on 24 Apr 2003, 8:10 p.m., in response to message #4 by Michel Beaulieu The chips are basically : Control and Timing, Arithmetic and Registers (those 2 chips form the 'CPU'), 2 ROMs, RAM, and Clock Driver/Init. I have (hopefully) sent you some information by e-mail describing the chips, and what they do.

Re: HP-45 problem Message #6 Posted by Tony Duell (UK) on 24 Apr 2003, 8:02 p.m., in response to message #1 by Michel Beaulieu Alas it most likely is a custom chip that's failed (or at least I can't think of a keyboard or PSU problem -- the sections that use standard components -- that could cause this fault). My first guess (without seeing the machine) is that one of the 2 ROMs has failed. Second guess would be either the A&R or C&T chips. The ROMs would have to come from another HP45, the other 2 chips are used in some other classics.

[ Return to Index | Top of Index ]

Go back to the main exhibit hall