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Hello all,

Just obtained an HP 8935 test set that has been sitting unused for several years. Upon power up the display indicated "AA memory battery low. See HELP menu"
I removed the rear cover and found the AA battery holder, corroded and nearly dead batteries. Not unexpected. Cleaned it up, put in new AA batteries, powered up the set and started checking various functions. So far so good. Powered the set down.

Returned a few days later and powered the set on. After self check the display now reads " Internal memory battery low, See Help menu"?
The HELP menu just says the internal memory battery is not user serviceable- contact HP customer support. ( sheeyah right ! )

Ok, before I start disassembly of the set, does anyone know which board the internal memory backup battery is on? What type it is? Solder in or in a holder?
?Any help is appreciated.

Thank you.
Shane Ke6jz

Hi Shane,

?

I am working on reviving a HP 8921A, that has the memory battery of 3V that is PCB mounted LIPO type. These batteries will supply quite a bit of current. The AAA Battery may be too much drain for it. The technology is 74HC era .

Hope this is of some assistance .

73s

Bill M.??? (VK6II)

Guys:

I own an HP 6381A with the on-board back up battery on the memory board.

Since these batteries are becoming increasingly difficult to find with the leads welded to the battery body,?
I recommend you purchase a socket and replace the battery with the socket.? Don't rely on Batteries-Plus,
as they don't do this procedure any more, and don't try to solder leads to the battery directly as the heat
from your soldering iron may cause it to explode!

I found the sockets?on Amazon at:



(Make sure you select the "CR2477" box!)?

Afterwards, changing out the battery on the memory board is a much more simplified procedure.?
Make sure you order the battery socket that lies flat on the board with the two pins out the bottom of the socket
and not the vertical-mount socket that mounts perpendicular to the board.? Also, pay attention to
polarity when you mount it!

I don't recall which board is the memory board, but it's the only board with a back-up battery?
mounted on it.? It's an easy find when you look down into the boards with a penlight.

Rick Hendricks
KE0GB

Hank,
Thank you for the information. This should point me in the right direction. I'll post a photo of the memory board when I get it out.?
Seems like the CR2477 would be in a socket already, but of course I haven't seen it yet. And yes, a socket is the only way to go.
Shane Ke6jz

Photo of actual board with backup battery soldered in. Looks to be the original battery.
Thanks Zl1cvd for your photos showing a battery holder. I was wondering if a holder would raise the overall height of the battery such as it would interfere with the adjacent
board, but your photo seem to indicate that sufficient spacing exists for? a holder. Now to order the correct holder.