The Museum of HP Calculators

HP Forum Archive 19

[ Return to Index | Top of Index ]

HP.45 Keyboard - Dead Row
Message #1 Posted by John Stark on 23 Mar 2010, 4:48 p.m.

Recently purchased a nice HP.45 calculator on the Unmentionable Site.

The only issue is that no keys on the bottom row register when pressed.

Disassembled unit, and found no issue by visual inspection (broken trace etc.)

All LED segments light up OK.

It appears either the bottom row is not getting "strobed", or the return from that row has an issue (either electronic or mechanical).

Any ideas would be appreciated.

Thanks.

John Stark

      
Re: HP.45 Keyboard - Dead Row
Message #2 Posted by John Robinson on 23 Mar 2010, 7:25 p.m.,
in response to message #1 by John Stark

Hi John,

I am not familiar with the 45, but you should be able to find all the information you need to trace the correct line all the way back to the CPU chip. The following will help :

1. Tony Duells article Inside the HP45 gives some good background to the HP 45 internals.

2. The PPC DVD should have the circuit diagrams for the 45 (it has the circuit diagrams for the HP 65). You need to contact Jake Schwartz to purchase the DVD, see PPC DVD

I hope that helps.

Cheers, John

      
Re: HP.45 Keyboard - Dead Row
Message #3 Posted by ClausB on 25 Mar 2010, 7:00 a.m.,
in response to message #1 by John Stark

I recently disassembled and cleaned my 45 and found a few cracked solder joints on the long gold pins that connect the two boards. Use a magnifier to look for cracks and use a clamp to hold the pins straight while resoldering.

      
Re: HP.45 Keyboard - Dead Row
Message #4 Posted by John Stark on 26 Mar 2010, 8:32 a.m.,
in response to message #1 by John Stark

Thanks to all for your help !


[ Return to Index | Top of Index ]

Go back to the main exhibit hall