Moving JM132 causes no change so instrument is stuck in this loop. Has anyone seen this and a fix?
This error is related to the internal calibration nv-SRAM, U132, which contains all calibration and auto-calibration constants.
Obviously, this RAM cannot be read anymore, either it's a defect of the RAM itself, or the internal battery / backup circuit is pulling down the RAM, maybe due to a completely depleted battery.. I've never before heard about that specific error.
How old is your instrument? Or maybe you know, how old this U132 is (date code). It has a life time of at least 10 years, and then fails by certain memory error messages.
KS will do the repair by exchange of the complete PCB, otherwise you could exchange the SRAM (from maxim/DALLAS) by yourself, but probably, the calibration is already lost, and a complete calibration is necessary.
PS: Theoretically, a TTL OR gate, or a DEMUX component might have failed. You may check that first.
Thank you Frank, for the insight. This 3458a has the newer PCA Outguard board with the 2 supervisor ICs with the snaphat batteries. It seems one of the supervisor chips is disabling a line that should be enabled. I’m not sure where the Cal is stored with this configuration. If I enable the chip enable line it then ask to be calibrated and seems to cal ok. Problems now are it needs an ACAL if the power is cycled, I don’t like the hack for enabling the chip (disconnecting the battery) and I fear it may eventually lose its Cal constants.
in the volt-nuts community, there is no experience, what really happens on depleted SnapHat batteries.
If I understand you correctly, you can unlock the CALRAM (probably U111) by disconnecting its SNAPHAT battery (probably on top of U133, the SRAM/battery supervisory circuit). What is the date code on this battery?
You can probably measure the voltage, and I bet, that it's dead or very low.
You may simply buy new SnapHats and replace the old ones during powering up the instrument.
I assume, that your CAL data are already corrupted, as your 3458A always requires CAL or ACAL after boot.
Is the DCV reading off? The firmware obviously loads the default value of 7.200 V for the LTZ1000A reference, whenever the calibrated value is corrupted.
From the pictures of the new outguard controller board A5, which is plug-in compatible to elder boards, I guessed that 128kB SRAM U111 replaces the CALRAM, and U112, U113 (256kB in total), with back-up battery on U132 , replace the 2x32kB nvRAMs for work space RAM, setup and programs, plus the 128kB buffer RAMs (opt. 01).
That battery should also be replaced, but it's not critical.
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