I just got my 8400A after a fed ex screw up or two, no worries it arrived intact just delayed slightly.
Only problem is i get it and the display doesn't light up, i know HV is present because the + lights up on DCV and it appears to work as part of the display changes as i change inputs.
The only thing that does not work it seems are the actually numeric part of the display, i know one or two tubes could be bad but all of the except for the +- seems unlikely to me.
It appears some of the transistors got very hot at some point, see pictures,
This thing appears to have been sitting on a shelf since the 80s judging by the amount of dust, mild rust and or corrosion but nothing that should be an immediate issue.
Also it was made sometime in early '73 judging by the date codes.
I know it is not a factory dud due to the 5 calibration stickers on it, 4 local and 1 from fluke.
Also of note it has from the factory, Ac converter, OHMs converter, Data output unit (DOU), Remote control unit (RCU) and Rear input. someone later added the card for DC external reference (DC-ER)
There is only one unfilled card slot and two missing options, does this mean someone also added the RMS converter? Crazy as it may sound i would prefer it if it measured peak to peak AC.
I can't find the 8400A manual for free though I can find the 8300A one, can it be used or should i just buy the 8400A manual?
I would greatly appreciate help, hints or even a general clue what to look for.
P.S. It is only 6 digit nixie tube meter, not 6.5 digit.
EDIT: For typos.