{"id":284,"date":"2015-08-27T14:10:00","date_gmt":"2015-08-27T14:10:00","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/video-equipment\/uncategorized\/test-equipment-and-fault-diagnosistracing-intermittent-faults\/"},"modified":"2015-08-27T14:10:00","modified_gmt":"2015-08-27T14:10:00","slug":"test-equipment-and-fault-diagnosistracing-intermittent-faults","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/video-equipment\/test-equipment-and-fault-diagnosistracing-intermittent-faults\/","title":{"rendered":"TEST EQUIPMENT AND FAULT DIAGNOSIS:TRACING INTERMITTENT FAULTS."},"content":{"rendered":"<div class=\"aoeow6a0dc930d3eaf\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '61e5902552e2353963d8d2f1bd1f4a8f',\n\t\t'format' : 'iframe',\n\t\t'height' : 250,\n\t\t'width' : 300,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/61e5902552e2353963d8d2f1bd1f4a8f\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.aoeow6a0dc930d3eaf {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.aoeow6a0dc930d3eaf {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.aoeow6a0dc930d3eaf {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.aoeow6a0dc930d3eaf {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.aoeow6a0dc930d3eaf {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<h3 align=\"justify\">TRACING INTERMITTENT FAULTS<\/h3>\n<p align=\"justify\">Of all equipment malfunctions, intermittent faults are the most dif\ufb01cult and frustrating to trace and diagnose. Provided that operating conditions are not \u2018borderline\u2019, i.e. weak tacho pulses, low supply- line voltage, PSU starting resistor gone high resistance etc., they usually have their origins in mechanical or \u2018thermal\u2019 effects. Bad jointing on PCBs or within components, as well as hairline board cracks etc., can usually be traced by \ufb02exing, probing and tapping of PC boards \u2013 once the fault has been made to appear, use test equipment to <i>p<\/i><i>r<\/i><i>o<\/i><i>v<\/i><i>e <\/i>its origin for a de\ufb01nite diagnosis.  <\/p>\n<p align=\"justify\">Intermittent faults which are temperature-dependent can often be traced to a single component (very often a semiconductor) by the alternate use of gentle heat from a hairdrier and an aerosol freezing spray. The most vulnerable and suspect components for thermal faults are diodes, transistors, ICs and to a lesser extent ceramic and electrolytic capacitors. \u2018Mechanical\u2019 intermittent problems are most often due to dry joints (sometimes concealed under an apparently good solder blob), potentiometers, switches, plug\/socket interfaces and board-print faults. The most vulnerable joints are those which carry heavy (e.g. scanning and primary power) currents, and those which support heavy or iron-tagged components like transformers and large electrolytic capacitors.  <\/p><div class=\"rukpx6a0dc930d4059\" ><script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-0778475562755157\"\n     crossorigin=\"anonymous\"><\/script>\n<!-- 300x600 television-and-video -->\n<ins class=\"adsbygoogle\"\n     style=\"display:inline-block;width:300px;height:600px\"\n     data-ad-client=\"ca-pub-0778475562755157\"\n     data-ad-slot=\"6549443290\"><\/ins>\n<script>\n     (adsbygoogle = window.adsbygoogle || []).push({});\n<\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.rukpx6a0dc930d4059 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.rukpx6a0dc930d4059 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.rukpx6a0dc930d4059 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.rukpx6a0dc930d4059 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.rukpx6a0dc930d4059 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"bwdfs6a0dc930d3f87\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '0c1eb4c533eaedb7b996f49a5a4983a9',\n\t\t'format' : 'iframe',\n\t\t'height' : 300,\n\t\t'width' : 160,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/0c1eb4c533eaedb7b996f49a5a4983a9\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.bwdfs6a0dc930d3f87 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.bwdfs6a0dc930d3f87 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.bwdfs6a0dc930d3f87 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.bwdfs6a0dc930d3f87 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.bwdfs6a0dc930d3f87 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\">The main aim in diagnosis of intermittent faults should be to get <i>positive <\/i>indications of the identity of the faulty component or section. Thus a solder-up of suspect board joints or replacement of suspect components followed by a fault-free test period is not as satisfactory as a cross-substitution test of stages, panels or individual components, in which the fault can be reproduced <i>i<\/i><i>n isolation<\/i>. Whether this takes the form of transferring an intermittent blue picture to an intermittent green one by interchanging B- and G-output transistors, or an indisputable meter reading at some crucial point in the circuit during the presence of the fault, it gives complete con\ufb01dence in the diagnosis and the repair.  <\/p>\n<p align=\"justify\">It is important to glean every clue from the equipment user in cases of alleged intermittent faults. Analysis of these can considerably narrow down the \ufb01eld of search. In difficult cases, it is necessary to leave the equipment with diagnostic instruments (ideally redundant and aged test gear saved for the purpose) hooked semi-permanently on key test points.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>TRACING INTERMITTENT FAULTS Of all equipment malfunctions, intermittent faults are the most dif\ufb01cult and frustrating to trace and diagnose. Provided that operating conditions are not \u2018borderline\u2019, i.e. weak tacho pulses, low supply- line voltage, PSU starting resistor gone high resistance etc., they usually have their origins in mechanical or \u2018thermal\u2019 effects. Bad jointing on PCBs [&hellip;]<br \/><a href=\"http:\/\/machineryequipmentonline.com\/video-equipment\/test-equipment-and-fault-diagnosistracing-intermittent-faults\/\" class=\"more-link\" >Continue reading&#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"aioseo_notices":[],"views":732,"_links":{"self":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/284"}],"collection":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/comments?post=284"}],"version-history":[{"count":0,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/284\/revisions"}],"wp:attachment":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/media?parent=284"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/categories?post=284"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/tags?post=284"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}