A Homebrew AC Upgrade For The Fluke 8840A

[William Dudley] picked up a Fluke 8840A bench multimeter at an auction, but was unhappy to discover out that it was looking at resistances inaccurately. It was also missing the optional board to help AC measurements. Wanting to use the otherwise attractive meter, he established about restoring and upgrading the unit.

Thankfully, the 8840A was from a time when Fluke used to openly publish schematics in its manuals. Therefore, merged with getting a glance at some photographs on the internet, it was simple for [William] to recreate the primary AC “Option 09” board to allow the sought after performance. As is commonly the way, his initiatives did not perform initially time, but after some bodge wires ended up set up, all was well. [William] reports the measurements are “reasonable, it’s possible even sufficient” with no calibration carried out.

Restoring the resistance challenge was uncomplicated. It turned out to be corrosion on the selector switches, discovered when superior-resistance measurements have been correct, but lower-resistance measurements weren’t. A little bit of flick-flacker with some make contact with cleaner sprayed into the switches obtained issues doing work once more nicely.

It’s nice to see aged hardware restored to total functionality, particularly when it is as attractive and very well-constructed as an previous Fluke meter. Bringing again old applications from the dead? You know we wanna hear about it!