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Thread: HP8920B A8 Module Back up battery.

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    Default HP8920B A8 Module Back up battery.

    Does anyone know what exactly this battery backs up? The Repair Manual glosses over the replacement .

    I am only doing this as preventative maintenance. Not having any test set faults, nor do I want any.


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    That series has a global stored profile, and individual setup memories. They are probably maintained in battery-backed-up RAM memory, or it could be E2PROM. It may have a clock for realtime stamping and internal logging, so it would probably back up the clock and settings memory. Note - just a guess, I have used them before but never serviced one, yet...

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    Im about to pull down my 8924C to fix the PSU. Maybe Ill find some answers while Im in there!

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    Will be interested in knowing this as well. I have a "old stock" 8920A that was HP branded but looks like it came from the Agilent factory new in 2005 with its factory cal sticker on it. I got it for a ridiculously good price so I couldn't say no - and it seems to still be holding my RTC and settings data just fine. I wonder what the rated service life of the battery is now.

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    I will probably wire in supplemental battery power when doing this, but if there is calibration data in there I might hold off for some plan b approach.

    I am of the if it's not busted why fix it mindset, but I found another piece of gear with similar battery and it is nearly depleted, so I bought batteries for that and some radios that are in their second and third decade.

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