{"id":1258,"date":"2020-03-12T19:53:54","date_gmt":"2020-03-12T23:53:46","guid":{"rendered":"http:\/\/www.nuclearphysicslab.com\/npl\/?page_id=1258"},"modified":"2020-03-17T23:07:23","modified_gmt":"2020-03-18T03:07:23","slug":"resurrecting-an-antique-mca","status":"publish","type":"page","link":"http:\/\/www.nuclearphysicslab.com\/npl\/npl-home\/spectroscopy\/software_and_hardware\/resurrecting-an-antique-mca\/","title":{"rendered":"Antique MCA"},"content":{"rendered":"\n

A friend gave Tim this old MCA that was disused and about to be discarded. Tim took it on as a winter project and enlisted the help of the group one by one. This is a real museum piece from the late 1960. It has a conversion gain of 256 channels and uses *volatile* core memory. <\/p>\n\n\n\n

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The refurbished MCA displaying a 137Cs NaI gathered spectrum.<\/figcaption><\/figure>\n\n\n\n
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The core memory board. Luckily this was still in-tact.<\/figcaption><\/figure>\n\n\n\n
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The pulses from the spectroscopy amplified as seen on a period correct, Tek 547 Oscilloscope.<\/figcaption><\/figure>\n\n\n\n
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The MCA actually had a digital output to drive a teletype at ~110 baud. The output circuitry was modified to output RS-232 at 1200 baud. But, one of the RS-232 bits was locked high. It just dumped the data one way, there is no handshaking.<\/figcaption><\/figure>\n\n\n\n
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Baud rate was confirmed with my inline RS232 protocol analyzer.<\/figcaption><\/figure>\n\n\n\n
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We had to trouble shoot the modified communication board, which was deeply nested in the unit. To make matters a bit more challenging, the home-made data lines were all purple without any other form of labeling… (be kind to the next person, even if it is 5 decades later) <\/figcaption><\/figure>\n\n\n\n
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Using an oscilloscope with infinite persistence on, one can see that the 7th bit is alway high. <\/figcaption><\/figure>\n\n\n\n
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A bit of surgery and we have all bits talking…<\/figcaption><\/figure>\n\n\n\n
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To be cute, I started it out, carried on a bit by Brother Lou, then Jimbo, and Brian, we wrote a little HP Basic code on the HP85B to listen for the RS232 dump, save the data, and plot the spectrum both on the CRT and make a hard copy to the thermal printer.<\/figcaption><\/figure>\n\n\n\n
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Nice 137Cs spectrum.<\/figcaption><\/figure>\n\n\n\n
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Looks about the same.<\/figcaption><\/figure>\n\n\n\n
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Mounted it all up in a small relay rack.<\/figcaption><\/figure>\n\n\n\n
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The complete 1960’s dream nuclear spectroscopy lab! (thought the HP85B was from the 70s)<\/figcaption><\/figure>\n\n\n\n
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We end with a 60Co spectrum.<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

A friend gave Tim this old MCA that was disused and about to be discarded. Tim took it on as a winter project and enlisted the help of the group one by one. This is a real museum piece from the late 1960. It has a conversion gain of 256 channels and uses *volatile*…<\/p>\n

Read More Read More<\/span><\/a><\/p>\n","protected":false},"author":3,"featured_media":1259,"parent":122,"menu_order":5,"comment_status":"closed","ping_status":"closed","template":"","meta":{"advanced-sidebar-menu\/link-title":"","advanced-sidebar-menu\/exclude-page":false},"categories":[61,3,47,37],"tags":[],"_links":{"self":[{"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/pages\/1258"}],"collection":[{"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/comments?post=1258"}],"version-history":[{"count":4,"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/pages\/1258\/revisions"}],"predecessor-version":[{"id":2001,"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/pages\/1258\/revisions\/2001"}],"up":[{"embeddable":true,"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/pages\/122"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/media\/1259"}],"wp:attachment":[{"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/media?parent=1258"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/categories?post=1258"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.nuclearphysicslab.com\/npl\/wp-json\/wp\/v2\/tags?post=1258"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}