Uploaded October 2022 | Updated September 2026, 2 weeks ago

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In this video, I document the Heathkit IM-105 Volt-Ohm-Milliammeter, which I added to my collection out of curiosity about how Heathkit managed to 'kit-ify' an existing commercial product, in this case the Weston model 660 multimeter.

Here are the time marks of the various sections:
00:00 History
07:48 Internal views
21:56 Overview
30:54 Test leads
31:23 Demonstration
46:44 Beauty shot
47:00 Back panel
48:57 Complete meter with new test leads
49:08 Manual overview
58:47 Schematic diagram and circuit theory

I have prepared a 4-drawing documentation package, CAD drawn, for this meter in PDF format. It also applies to the Weston model 660 multimeter. It includes a full schematic diagram, assembly/disassembly instructions, calibration procedure, specifications, case and printed circuit board (PCB) layouts, selector switch details, and theory of operation. It may be downloaded from:

serpentwebsite.com/Heathkit_IM-105_&_Weston_660_schematic_&_servicing.pdf