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Negative.
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It is indeed directly due to Schottky diode degradation,
? as stated in the Hp Service Bulletin 4274a-12?? ,? referenced above:
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" Improvement for Memory Backup Battery"
? ...
" Symptom and Cause:
The characteristics of the Schottky didoes used for CR3 and CR4 in the level detector circuit on the A9 MPU board gradually deteriorate.? This causes increased reverse bias current which significantly shortens the life of the memory back-up battery.
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Implementation:
To prolong battery life, the Schottky diodes ( 1901-0518 ) should be replaced with general purpose diodes.? The part number of the recomended replacement diode is : Hp? P/N: 1901-0025? "
?
-- My question is:
? What? other Hp instruments? *might* ? this modification for Schottky diode replacement
????? in Sram Battery ( non Dallas )? back-up circuits, ? apply ?
?
rick
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