Hi All,
I know this subject has come up before but I could not find a final solution .
I picked up a very nice deal on Ebay for a HP3457A
That Has a Cal sticker on it 10 years ago.
I powered it up all the Test pass OK and the self Acal work Ok .
No errors . WOW this has to be too good to be true . Left it on the bench running for a few hours .
after about half an hour an almighty BANG . The Mains line filter had decided to leave the room ..
the metal tin was burst open and all the sticky smelly stuff had oozed out .
Did a clean up and replaced it with a temporary socket .
All started up fine No Damage other than the house stunk of burnt plastic .
I checked the Ram battery which is a Panasonic BR-2/3A with a date code 2344 . which is by my reckoning 1992 3 day of week 44
27 years it still measured 3.36 volts but I know that these batteries can show good and then have a rapid drop off . instant death .
The only Battery I had available was a CR123 Duracell (3.260 v)
So I have a Battery operated isolated soldering Iron and I soldered 2 Patch leads to the board and connected the new battery as a piggyback with a Schottky diode IN5819
as it has a very low voltage drop 0.26v compared to the diode on the hp board which has 0.6v drop apx .
So if the old battery does do a dirty on me . the CR123a hopefully will save the Calibration .
Has any one done some thing similar as the BR-2/3A are a commercial cell and are far better but at the moment the post is hopeless and some of the stuff from Ebay
is taking way longer . OK its lasted 27 years and I have seen these last 30 + years but the drop off can happen within a hour . And relying on Murphys Law
Is there another alternative way of doing this ??
So any help on this would be appreciated .
Thanks