Inspired by these nice pictures of a 3468a battery change
https://www.eevblog.com/forum/testgear/quick-question-about-hp-3468a/msg197337/#msg197337http://mrmodemhead.com/blog/hp-3468a-battery-replacement/I decided to check/change the battery in my HP 3478A
SN : 2911A66xxx - Means : (29+60 = 89) = 1989 , Week 11 , A(merica)
My serial is almost the same as Daves , and i have the same yellow battery in.
https://www.eevblog.com/forum/blog/eevblog-427-hp-3478a-multimeter-teardown/msg194349/#msg194349I just measured the battery to 3.4170v - with a Agilent 34401A , and Bravo said "watch out" here.
https://www.eevblog.com/forum/blog/eevblog-427-hp-3478a-multimeter-teardown/msg195033/#msg195033I have been preparing a bit , and have gotten som Lithiums from the "net" , even 2 Taradians.
But they have the "reverse polarity" , meaning - on the dual pins and + on the single pin.
I also have a "perfect fit" but it's only a 3v Lithium , could i use that ?.
I have attached some pics , and "snipped" 3 pages from the service manual to give an idea of the buildup.
The Ramchip (U512) in pg. 154 , and the battery circuit with CR764 on pg. 156.
On the schematic they say 3.0v , so i hope i can use the 3v Lithium.
But will not if anyone says its really a bad idea.
Hope to get some advice now that i have the "lid off" and is all "warmed up".
I have prepared a spare Taradrian with an 1n4148 on + , have a propane solder iron ready.
I'll leave the meter powered on mains and solder the spare taradrian across C510 , and then desolder the original battery , and solder the new one in.
Edit: I just found this with the same part£ as in HP's manual
http://www.ebay.com/itm/1420-0278-Agilent-HP-Lithium-Battery-3V-95A-for-3478A-/350546682442It's a 3v Lithium , so i think i should be ok or ?
TIA
/Bingo