Just a heads up on this DMM. I was ordering a new VFD tube for a repair on a Fluke 45, Fluke stated to me that parts for this unit were on a last time buy. If you have a dim display, you might want to buy a spare before they're all gone. Part was $36 and change. Well worth the cost to keep these running.
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While it is is preferable in this case to just spend the $36 and replace the tube, out if interest, there are 2 things that you can try with VFD's, if you can't get a replacement tube
Running a magnet over the front of the tube
Disconnecting the tube and putting a higher than the normal heater voltage (50% more from memory) across the heater filament (usually the heater is connected to the pins at the ends of the VFD tube) to heat them to a little over a dull red colour for a few seconds (you then connect back to the normal heater supply) can restore brightness for some extra life.
I can understand running the heaters at a higher voltage to increase their emission, but what effect would a magnet have?
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