MORNING STAR OBSERVATORY
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Simpson Model 360-2 Digital Multimeter

This meter is a good example of why I now try not to buy vintage electronics from a certain online auction site. Advertised as being "collector quality", outside it was in decent shape but inside it was a trashed rat's nest. Some hack had miswired or disconnected the wiring to the internal fuses, the external power connector and the batteries, and had completely destroyed the delicate analog meter movement. No wonder the seller made sure to say he had "forgotten" to take any pictures of the inside of the unit.

The meter is from the mid 1970's and is kind of a digitized version of the venerable Simpson 260. I like that it is auto polarity, and for resistance measurements has a low power 200 ohm range and also a 20 Megohm range. The small analog meter would have been useful for checking capacitor leakage or peaking up alignments, things a digital readout fails miserably at.

Picture
The 360 is powered by 4 NiCd C-cells or the wall wart charger, if connected. It can also run off 4 Alkaline C-cells, but the wall wart should be disconnected so it doesn't attempt to charge them.

The case is in pretty good shape other than some scratches on the face and the trim of both knobs. But it's not "collector quality", unless your standards are a bit low.

Picture
Internally, some of the battery contacts were ruined by leaky batteries, and the wiring to the battery compartment was completely miswired. New battery contacts were made from sheet brass to replace the contacts that couldn't be cleaned. I found a schematic online and sorted all the wiring to the batteries, charger connector and the two fuses for the low ohms and low current scales. Plus there were numerous wires broken off at the PCB from being flexed too much and several capacitors with broken leads or corrosion that needed replaced.

When first powered up the meter would zero but trying to measure anything caused it to immediately go over range. This was traced to an LM2901 quad comparator with three bad sections. It's in the upper left corner of the PCB in the IC socket. There was just enough clearance to add a socket while replacing the IC.

Picture
​After finishing up with a good cleaning and an initial calibration it's all working except the small analog meter. That was totally destroyed internally and is unobtanium now days.

Picture
Here's the guts of the destroyed meter movement. It's looks like it was made specifically for the 360-2, so not much chance of finding another one just laying around. But who knows, maybe someday I'll stumble across some kind of an edge meter that will fit the panel opening.

Picture
Here's the parts replaced which includes corroded capacitors, caps with broken leads, and the bad LM2901.

Picture
After calibrating the meter it is very accurate across all ranges. In this photo it is connected to my signature tracer's meter output and is measuring the breakdown voltage of a zener diode.

Page Created 2/22/2020
Last Updated 4/18/2021
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  • Home
    • About
    • Contact
  • Astrophotography
  • The Observatory
    • The New Observatory
    • - About the ExploraDome
    • - About the Lancaster Dome
    • - Building the Lancaster Dome
  • Equipment
    • CCD Cameras >
      • Orion Starshoot Pro
    • Mounts >
      • Orion HDX110 (EQ-8)
    • Telescopes >
      • Astro-Tech AT6RC
      • Celestron C-11 XLT
      • Zhumell 152mm Refractor
  • Projects
    • C11 XLT Mods
    • Orion SSPRO Camera >
      • Disassembled Views
      • Noise Reduction Mod
      • Temp Controller Mod
    • Ultima 8 Mods
    • Zhumell Refractor Mods
  • Non-Astronomy
    • Amateur Radio >
      • Boat Anchor Radios >
        • BC-348N Receiver
        • Collins 51J4 HF Receiver
        • R-392 HF Receiver
      • DIY >
        • Station Boom Microphone
      • Ameco >
        • Ameco AC-1
        • Ameco OCM
        • Ameco PT-2
        • Ameco R5A
      • Heathkit >
        • Heathkit SB-102 Station
      • Knight-Kit >
        • Knight Kit Span Master II
      • Yaesu FT-817 >
        • Yaesu FT-817ND
        • LDG Z-817 Autotuner
        • Windcamp LiPo Battery
    • Antique Radios >
      • Building A Radio Workbench
      • Radio Dial Neon Clock
      • Radios >
        • 1938 Zenith 6-S-254
        • Echophone EC-1
        • Eltz Radione 2
        • Panasonic RF-5000A
        • Silvertone Model 4465
    • Geiger Counters >
      • AN/PDR-27G Radiac Set
      • Lionel CD V-700 Geiger Counter
      • RCA WF-12A Geiger Counter
    • Test Equipment >
      • DIY Test Equipment >
        • DIY Curve Tracer
        • DIY Signature Tracer
      • Military Test Equipment >
        • BC-221-AF Frequency Meter
        • LM-21 Frequency Meter
        • TS-323/UR Frequency Meter
        • TS-465 C/U Sweep Generator
        • TS-505D/U VTVM
        • TV-3C/U Tube Tester
      • Tube Testers >
        • Alternating Current Sink
        • Drug Store Tester
        • EMC Model 200 Tube Tester
        • Hickok Model 6000A Tube Tester
        • Hickok OZ-1 (550X)
        • Precise Model 111 Tube Tester
        • Precision Model 10-12
        • Supreme Model 385
        • TV-3C/U Tube Tester
      • VTVMs and Multimeters >
        • B&K Model 290 Hi-Low FET Multimeter
        • Hickok 225K VTVM
        • McMurdo Silver VOMAX 900
        • Micronta 22-220 FET Multimeter
        • Simpson 360-2 Digital FET DMM
        • TS-505D/U VTVM
      • Hickok >
        • Hickok 19X RF Generator
        • Hickok 225K VTVM
        • Hickok 288X RF Generator
        • Hickok OZ-1 (550X)
        • Hickok 6000A Tube Tester
      • Simpson >
        • Simpson 360 DMM
        • Simpson 360-2 DMM
        • Simpson 480 Genescope
      • Supreme Instruments >
        • Supreme 385 Automatic
        • Supreme 560 Vedolyzer
        • Supreme 560A Vedolyzer
        • Supreme Model 561 AF/RF Generator
        • Supreme's Model 562 Audolyzer
        • Supreme Model 562 Audolyzer circa 1941
        • Supreme Model 562 Audolyzer circa 1946
        • Supreme Model 563 Audio Generator
        • Supreme Model 576 RF Generator
      • Other Test Equipment >
        • Rider 162 Chanalyst
        • Tektronix 326 O'scope
        • VU-Data Model 941B Oscilloscope
    • ---------------
    • Fossils
    • Rocks and Minerals
    • Star Trek >
      • Star Trek Rock Mood Lamp
      • Star Trek Communicator