{"id":14516,"date":"2017-11-13T11:10:37","date_gmt":"2017-11-13T16:10:37","guid":{"rendered":"http:\/\/scruss.com\/blog\/?p=14516"},"modified":"2025-02-17T12:54:46","modified_gmt":"2025-02-17T17:54:46","slug":"soltec-hm-102s-unboxing-a-30-year-old-multimeter","status":"publish","type":"post","link":"https:\/\/scruss.com\/blog\/2017\/11\/13\/soltec-hm-102s-unboxing-a-30-year-old-multimeter\/","title":{"rendered":"Soltec HM-102S: unboxing a 30 year old multimeter"},"content":{"rendered":"

Hey!<\/strong> I don’t have this meter any more.<\/span> The scanned manual is all I can help you with (see link near end of article)<\/em><\/p>\n

Graham Green<\/a> had a stall at Make Change<\/a> yesterday. Graham’s the former manager of Active Surplus, the much-missed Toronto surplus emporium. He had some military-surplus multimeters that hadn’t seen daylight since I was in school. That’s a while back: this<\/a> (unfortunately<\/em>) was #1 the week I left school. So I bought one of Graham’s meters just to see what was inside \u2026<\/p>\n

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Neatly packed in mil-spec cardboard with a date code of 7\/86. There’s a fair chance that Papa Don’t Preach<\/a> was on the radio somewhere when this was sealed<\/figcaption><\/figure>\n
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Inside the box, the meter’s sealed in a pouch. Mil-spec doesn’t allow anything to rattle about, after all. Unlike some surplus stuff, this looks 99.999% mouse-piss free<\/figcaption><\/figure>\n
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Under the meter was this battery pouch, which exhibited the qualities of both \u201ccrunchy\u201d and \u201csquishy\u201d. Neither of these are things I look for in a battery, so these weren’t going in the meter<\/figcaption><\/figure>\n
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Battery pack dated January 1986. This isn’t going to be good.<\/figcaption><\/figure>\n
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Daylight \u2026 for the first time in 31 years! On first glance, everything looks okay, but three decades of phenolic off-gassing was much in evidence \u2014 pew!<\/figcaption><\/figure>\n
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Despite the hermetic seal, the elastic band had rotted to dry pasta consistency. Note expired elastic band ichor on the manual cover<\/figcaption><\/figure>\n
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The test leads are still bright, shiny and very pliable. I suspect they might be silicone-encased, as PVC of this age has a habit of turning brittle (ask me about my late lamented Konix Navigator<\/a>s)<\/figcaption><\/figure>\n
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The meter. unpacked. A clear (if small) dial, complete with mirror scale to reduce parallax error<\/a> in reading. Hidden under the frosted cover is a small \u201cMade in Korea\u201d mark<\/figcaption><\/figure>\n
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Handy-dandy fold-out carrying handle that also doubles as a stand<\/figcaption><\/figure>\n
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Inside the case, ancient tooling marks. The plastic is thick and seems fairly robust. The captive mounting screw was a nice touch<\/figcaption><\/figure>\n
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A very analogue meter. Lots and lots of 1% tolerance resistors on the main board, plus a great big thumbwheel potentiometer for zero adjustment. The foam battery pad up top was as good as new<\/figcaption><\/figure>\n
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Up and running: no auto-off battery saving mode here! The test lead jacks didn’t have the shrouding we’d expect these days, so you won’t be able to use newer probes without modifying them<\/figcaption><\/figure>\n
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Things I Don\u2019t Miss from Analogue Meters, #1: setting the 0 \u03a9 point. Expect fiddliness and drift.<\/figcaption><\/figure>\n
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The test subjects: a 3.6 V Li\/SOCl\u2082 \u00bd-AA NVRAM battery (new: tests at 3.68 V on an Agilent U1242B meter), a 7.5 k\u03a9 \u00b1 5% resistor (tests at 7.52 k\u03a9) and a 39 k\u03a9 \u00b1 10% resistor (tests at 41.3k\u03a9)<\/figcaption><\/figure>\n
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Battery test: the Soltec reports 3.8 V, or within 5% of expected. This is where I really miss auto ranging<\/figcaption><\/figure>\n
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Not so good is the 7.5 k\u03a9 resistor: the Soltec reads just under 6 k\u03a9. Blame faulty zero setting from me, as it really is<\/em> fiddly and I just set this up quickly.<\/figcaption><\/figure>\n
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The 39 k\u03a9 resistor (which is really more like 41 k\u03a9) indicated 34 k\u03a9 on the Soltec. Again, my dodgy zero set is most likely to blame, but reading this little log scale isn\u2019t the easiest<\/figcaption><\/figure>\n

Would I recommend the Soltec as a general purpose meter? Not really. There are more capable multimeters<\/a> available for about the same price, and you don’t need to go as far as the unbelievably expensive Agilent DMM I use (or even the strictly ornamental analogue ex-Forces Bach-Simpson 635 multimeter<\/a> that graces\/clutters my workbench). It would need a video to show where analogue meters excel: in showing changing values and getting a rough idea of the limits. It would make a great battery tester, or \u2014 if coupled with a micro-controller with PWM or DAC ouput \u2014 part of a demo rig. If nothing else, it’s a great way to learn how to appreciate modern test gear and all it does for us.<\/p>\n

I’m probably going to regret this, but here’s a scan of the Soltec HM-102s manual<\/a>:<\/p>\n

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PDF link under image. I say I regret doing this, ‘cos every cheapo ebay seller of these things is now likely to download this and splat their own horrid watermarks over it, making the file huge and ugly. But the market’s gonna market, and I wouldn’t want to make a free manual inaccessible with DRM. By contrast, my<\/em><\/strong> watermark’s quite tasteful and doesn’t interfere with readability in any way \u2026<\/figcaption><\/figure>\n
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Postscript<\/strong>: you think I’d just throw away that expired battery pack without peeking inside? If so, allow me to call you Wrongo McWrongison of that erroneous ilk<\/strong><\/span>! The \u2018Hipower Super\u2019 cells weren’t looking so super: the leaked electrolyte had dried into a gritty, stinky layer. I couldn’t even find the terminals on the 9 V battery to try and test it, so grotty was the corrosion. Amazingly, the slightly-less-nasty AA cell at the front tested at 1.52 V, almost as good as it could have been in the mid-80s. Doesn’t mean it’s not going in the HHW bin with the others, though.<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

Hey! I don’t have this meter any more. The scanned manual is all I can help you with (see link near end of article) Graham Green had a stall at Make Change yesterday. Graham’s the former manager of Active Surplus, the much-missed Toronto surplus emporium. He had some military-surplus multimeters that hadn’t seen daylight since […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"Soltec HM-102S: unboxing a 30+ year old new-old-stock multimeter \u00e2\u20ac\u00a6","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[2],"tags":[2387,3098,2768,2816],"class_list":["post-14516","post","type-post","status-publish","format-standard","hentry","category-goatee-stroking-musing-or-something","tag-multimeter","tag-nos","tag-surplus","tag-unboxing"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pQNZZ-3M8","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/posts\/14516","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/comments?post=14516"}],"version-history":[{"count":12,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/posts\/14516\/revisions"}],"predecessor-version":[{"id":17764,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/posts\/14516\/revisions\/17764"}],"wp:attachment":[{"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/media?parent=14516"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/categories?post=14516"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/scruss.com\/blog\/wp-json\/wp\/v2\/tags?post=14516"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}