Hello,
On power up the instrument says "Cal ram checksum error re cal instrument." then when i try to calibrate, util->selfcal gives error "cal ram write protected." receive same error in util-> service. Running selftest I have
failed protected nonvolitile ram
failed D/A converter
failed A/D converter
i searched this forum and post topic: "cal ram checksum error (HP 54501A) ". except for the "cal ram write protected" error, the poster had the same experience (checksum error, and selftest fails). They recal'd and got scope to work. A dead battery was likely cause of checksum error.
Hoping i have a dead battery and that my selftest results are incorrect. Is that reasonable hope? what might cause the 'write protected' error???
On power up the instrument says "Cal ram checksum error re cal instrument." then when i try to calibrate, util->selfcal gives error "cal ram write protected." receive same error in util-> service. Running selftest I have
failed protected nonvolitile ram
failed D/A converter
failed A/D converter
i searched this forum and post topic: "cal ram checksum error (HP 54501A) ". except for the "cal ram write protected" error, the poster had the same experience (checksum error, and selftest fails). They recal'd and got scope to work. A dead battery was likely cause of checksum error.
Hoping i have a dead battery and that my selftest results are incorrect. Is that reasonable hope? what might cause the 'write protected' error???
The current replacement part for this is DS1230Y. I ordered mine from Mouser for around $15. I de-soldered the old 28 pin chip installed the new
NVRAM and no longer have the "cal ram checksum error re-cal instrument" error. You must also do the self cal to eliminate the selftest errors of
Proteced NVRAM, D/A converter, and A/D converter failures. I found the trick to be to boot the instrument with the rear panel cal protection in
unprotected position which typically causes the default cal to be loaded. After this run the Vertical and Delay self cals which use the rear panel
calibrator outputs. Of course all that "after" replacing the bad DS1235Y. The new DS1230Y says it has a life cycle of 10 years. You can see that
alot of these scopes are around 20 years old and this problem happens.