Products > Test Equipment
Fluke 8840A - AC reading PCB upgrade
home_listening:
Hello Hello,
I purchased a Fluke 8840A last year, without the AC reading option, and have been a happy user since then. Curiosity got the better of me recently and I decided to open it up and poke around and noticed that it actually does have the PCB internally, without the ribbon cable connected.
Of course, I plugged it in to see what happens. The meter fails to boot up and do anything meaningful. Works perfectly again when the ribbon is unplugged.
Have had a look around the AC card itself and taken care of a few suspect looking capacitors and I'm getting sensible readings between all the power rails on the card itself - yet still having the same problem.
Does anyone know if there are changes that need to be made on the motherboard/main PCB to handle the AC option? Service manual doesn't mention anything but I'm hoping there is something I've missed.
Thanks and kind regards
bdunham7:
Can you look very closely at the identifying marks and labels on the card? It is possible that you have a card for an 8842A which is very similar. If that is the case, I may want to swap with you!
EDIT: Just noticed you're in Oz. But look at the labels anyway.
home_listening:
All research points to it being the correct card. PN# 728899 Rev. N - matches the service manual image and schematic.
Cheers
bdunham7:
OK, that looks correct. Some of the earlier revisions had hand-penciled notations on the circuit board and could be less clear. There should be a separate number above that p/n that starts with either 8840 or 8842, but I think you have the correct one.
To answer your original question, no there is no modification or configuration of the main board that needs to be done when installing the AC board. Without it you get '30' when you press any AC function. Power down, plug it in, power up and the AC functions work. One snag is that if you swap in a different AC board or add it to a unit that has never had one, your calibration constants will be incorrect and the AC reading accuracy will be suboptimal.
I have not encountered your exact problem, but I do have several of these units, both 8840a and 8842a, and if you need me to test anything for comparison I can do it when I have one apart.
bdunham7:
Also, just out of curiousity, is the Option 09 box checked on the back panel of your unit? And does it have the IEEE-488 interface?
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