I need help diagnosing a HP9100B Message #1 Posted by Bruce Larrabee on 5 July 2012, 11:55 a.m.
I am trying to repair a HP9100B. This is a very complex machine. At least to someone that is used to integrated circuits.
I have a copy of the manual, the service manual and the schematic drawn by Tony.
I have tried running the diagnostic program from the service manual. No way. Then I tried running just the routine from the program that tests the SIN X, COS X, TAN X and ARC functions. When I ran just that
it completed without errors every other time and stopped with an error every other time. Next I single stepped through the routine a few times. What I discovered was that the routine was producing errors on every run but was only signaling an error every other time.
This made me realize that the diagnostic program is of extremely limited utility being as it could experience MANY errors and still run through completely and never indicate any problem whatsoever.
So here are the basic symptoms I have observed so far.
ADDITION SUBTRACTION MULTIPLICATION DIVITION WORK
IN DEGREES SIN X AND ARC SIN X WORKS FROM 58 TO 147
COS X AND TAN X TEND TO GET THE SAME VALUES AS SIN X
IF I USE ARC COS X AND ARC TAN X THEY ACTUALLY WORK
EVEN TO VALUES LARGER THAN 147 AND LESS THAN 58
LOG X FAILS AND LN X FAILS
E TO X WORKS BUT GETS NEGATIVE VALUES
SQRT WORKS
THE REGISTER FUNCTIONS WORK
THE PROGRAM CONTROL FUNCTIONS SEEM TO WORK
Any help any one can give me would be greatly appreciated.
Thanks,
Bruce
