Fluke 8375A DMM - Part 1

The Fluke 8375A is a digital benchtop multimeter, made around 1973. It supports DC voltage, +/- 1100V as primary function and comes with a module to convert an equal range of AC voltage to an RMS value. As an additonal bonus, it also has a built in current source to measure Ohms from essentially 100µ𝛀 up to 12M𝛀; It does not have built in current shunts however, so current messurement would need an exterman shunt resistor for reference. All of this to output to a 5 digit nixie display with an overflow digit for 20% overflow; i.e. the maximum number should be 120000 with the decimal point set according to the range. The "filter" function is also based on a real analog active low pass filter to even out fluctuations that would be visible to the AD converter. I've seen that as a "digital average" in most modern meters. So... let's see what this little gem has to offer in terms of problems and solutions!

Part one here is the disassembly, overview, recapping and cleanup procedure. Part two is from power on to some serious troubleshooting.

0:00 Intro / Overview
2:13 First Look Inside / Disassembly Start
4:28 Front Panel Issues / Power Switch
6:10 Binding Posts / Front Panel "before"
7:20 Function Indicator / Switch Block Cleanup
10:21 Solder Problem... and Fix!
11:42 Trigger Potentiometer
13:05 Transformer Section Dis- and Re-assembly!
15:18 Recapping! ...and PCB cleanup: Desoldering...
17:50 Power Supply Soldering, Heat Sink Polish
20:02 Mains Switch Cleanup
22:10 Terminal Block 1 / Transformer Sectino / Bending Tins
23:16 Terminal Block 2 / Power Switch Connection / Plastic Trim
24:39 Self Test Switch
26:18 Front Panel "after" / Assembling Binding Posts
28:42 Summary Part 1 / Credits / Outtake

Music (in order)

My Train's A Comin' - Unicorn Heads
Nine Lives - Unicorn Heads
Wrong - Dan Henig
Town of 24 Bars - Unicorn Heads
Light Expanse - Unicorn Heads

(YouTube Audio Library)

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