HP97 troubleshooting

[Prabhu Bhooplapur]

Hi,
My HP97 is having problems. It turns on with the correct display '0.00'. After this if I try to use the keyboard then say press the key '1' then the display changes to'-1000000000. 00' (the last two zeros are in the exponent position). This is same with any of the numeric keys except that the first digit is the key pressed. If I press say key '1' the display will be '-1000000000. 00', press ENTER, if I then press say key '2' the display will be '-2000000000. 00' and press '+' the answer is displayed correctly '3.00'. If I perform operations like X2 or SQRT X the result is computed correctly.

I tried using the HP97 diagnostic card. I read in both the sides of the card and the display changes to '0. 00'. On pressing key A to run the diagnostic program results first in the display showing '5. -07'(instead of the usual 57 on the display) followed by '-8. 00'.

Any clues to what could be the problem and any suggestions to solve the problem? Thanks,
Prabhu Bhooplapur

[Randy]

Realistically, you'll need good 97 to troubleshoot, first at the board level and then down to the component as the problem is most likely a bad ROM 6 (1818-0230). You can troubleshoot using the instructions in the 97 service manual on page 4-2.

Note: The service manual only shows the component locations for first generation logic board layout, the second one, done for the 97S, is not documented. Further, the rom locations shown in figure 4-9 are not correct. The order from left to right is ROM 1,2,6,5 and 3 and not 1,2,3,4,5 as shown.

HTH...

[Prabhu Bhooplapur]

Thanks Randy.

I will try and come back to this forum. Prabhu