{"id":5506,"date":"2020-09-10T11:01:00","date_gmt":"2020-09-10T01:01:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2020\/09\/10\/the-agony-of-troubleshooting-from-china\/"},"modified":"2025-07-21T19:09:12","modified_gmt":"2025-07-21T09:09:12","slug":"the-agony-of-troubleshooting-from-china","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2020\/09\/10\/the-agony-of-troubleshooting-from-china\/","title":{"rendered":"The Agony of Troubleshooting — From China"},"content":{"rendered":"<\/p>\n
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I am troubleshooting my beloved NYC HP8640B Signal Generator (thanks to Steve Silverman and Dave Bamford). Some of you may wonder why I don’t just replace this beast with something small, lighter, cheaper and newer. Well, I have not found any new sig generators that will do what this beast does: It goes all the way up to 256 MHz (higher with an extension kit). It has a great attenuator in it so you can set the output just where you want it. AM or FM modulation. Really useful. So I think I’ll fix it. <\/b><\/div>\n

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My problem is that the internal freq counter stops working above 16 MHz. Using the very extensive documentation, and without even really opening up the machine, I think I have located the fault. I think it is in the Counter Time Base Assembly board A8A3. Now of course, the fun begins. (Tips, advice, solutions, and words of encouragement would all be appreciated.) <\/b><\/div>\n

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While planning my assault on A8A3, I came across the web site of BH1RBG. He too has recently been working on an HP8640B. His problem was different, but when I read through his site I saw evidence that the agony of troubleshooting is something that is the same all around the world. Check out his description of the agony: <\/b><\/div>\n

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I even suspected the LM723 should had something bootstrapping circuit, make sure the Q4 sure start. Because the external reference VR3 is floating too, oh, my godness. <\/b><\/i><\/div>\n<\/p>\n
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I became hopeless, and ordered several LM732,and waiting delivery for days. This beast frustrate me so deeply, changed the LM723 does not help anything. And i almost desoldering everything in the board!<\/span><\/i><\/p>\n

Oh man, I’ve been there. Several times while in the throes of a troubleshooting battle I have actually had dreams of removing all the parts from a troublesome PC board.
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BH1RBG has a very interesting site with lots of ham radio projects: <\/b><\/p>\n

https:\/\/sites.google.com\/site\/linuxdigitallab\/rf-ham-radio?authuser=0<\/b><\/a><\/p>\n


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I am troubleshooting my beloved NYC HP8640B Signal Generator (thanks to Steve Silverman and Dave Bamford). Some of you may wonder why I don’t just replace this beast with something small, lighter, cheaper and newer. Well, I have not found any new sig generators that will do what this beast does: It goes all the … Continue reading “The Agony of Troubleshooting — From China”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":5507,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[173,22,171,170,71,25],"tags":[],"class_list":["post-5506","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bamford-dave","category-china","category-hp8640b","category-silverman-steve","category-test-gear","category-troubleshooting"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5506","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=5506"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5506\/revisions"}],"predecessor-version":[{"id":5508,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5506\/revisions\/5508"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/5507"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=5506"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=5506"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=5506"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}