Workshop Project #44 - SR 720 LCR Meter
So, the SR720 is a digital LCR meter from the 1990s. It is built in a "QC" form factor and feature set. That is, the whole layout and feature set is optimized for a workstation where an operator would check one component after the other to put make sure they are all within a specific range. That being said, the specs read quite good to me:
0.0001 Ohm to 2000MOhm, 0.0001pF to 99999µF, 0.0001µH to 99999H - that's just about all what the display can show. With test frequencies at 100, 120, 1000, 10k and 100k Hz with a typical accuracy of better than 1% in the "normal" ranges.
These are still found on eBay, with quite varying prices though. I've seen from 150 starting bid to 1500 buy now offers and quite a bit in between. But from what I can tell after looking at two of them: they might need PCB repair below the big electrolytics. These seem to leak quite some. The donor unit (a 715 model!) for the GPIB board I mentioned had several traces eaten away and was not working at all.
0:00 Intro / Overview
1:20 First Look / Disassembly Start
3:54 Power Supply Section
5:35 Display and Keyboard
7:12 Test Fixture with Explanation
8:38 Line Module and Power Switch
10:13 Assembly Start
12:17 Thermal Paste! / Recapping
14:03 Main PCB Installation / Test Fixture Assembly
16:55 Display and Keyboard Assembly
18:22 Case Closed! / First Try / GPIB?
20:10 GPIB and Handler Interface Test/Demo
21:22 Test Adapter: Overview and Disassembly
23:09 Test Adapter Assembly
25:40 Axial Adapters
26:53 Sample Measurements
28:03 Summary / 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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