{"id":2697,"date":"2012-06-12T14:46:28","date_gmt":"2012-06-12T19:46:28","guid":{"rendered":"http:\/\/w0ep.us\/OM\/?p=2697"},"modified":"2012-06-12T14:49:31","modified_gmt":"2012-06-12T19:49:31","slug":"ten-tec-century-21-power-supply-repairs","status":"publish","type":"post","link":"http:\/\/w0ep.us\/OM\/?p=2697","title":{"rendered":"Ten-Tec Century 21 power supply repairs"},"content":{"rendered":"

[Yesterday’s run: Watson Road; Today’s run: 2 miles plus 10×100]<\/p>\n

Over the weekend there was a VHF radio contest.\u00a0 VHF contests are kind of slow around here so I also dug into my Ten-Tec Century 21 to make some repairs.<\/p>\n

When I first got this radio the power supply was not working.\u00a0 I ended up replacing a large 2n3055 pass transistor and that seemed to do it.<\/p>\n

Then here recently I turned it on and it came on for a little bit, then the lights dimmed down and it went off.\u00a0 Kind of like if it were on a mostly-dead battery.\u00a0 But this rig plugs into the wall, no battery.\u00a0 A bad sign.\u00a0 After that, no life at all.<\/p>\n

So I pulled the cover off and found a burnt trace on the power supply circuit board.\u00a0 Fuse was fine (!), and everything else looked Ok.\u00a0 Pulled out the power supply board and put a jumper over the burned trace (today’s picture) using some solder-wick.<\/p>\n

After putting it together, it burned out the fuse.\u00a0 It was a 5 A slow blow fuse\u00a0 (too big).\u00a0 I took the power supply board back out.\u00a0 Poking around, I discovered that the voltage rectifier pack was not working correctly; one leg was shorted to another.\u00a0 And those legs were the ones which would cause that circuit board trace to have lots of current on it.\u00a0 Imagine that!<\/p>\n

Went to Radio Shack and purchased a new rectifier.\u00a0 The new one is slightly bigger but I made it fit ok.\u00a0 I purchased a new 2n3055 pass transistor also but did not end up using it.<\/p>\n

I put in a 1 Amp fuse this time.<\/p>\n

Now the Century 21 is back on the air.<\/p>\n

\"\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

[Yesterday’s run: Watson Road; Today’s run: 2 miles plus 10×100] Over the weekend there was a VHF radio contest.\u00a0 VHF contests are kind of slow around here so I also dug into my Ten-Tec Century 21 to make some repairs. When I first got this radio the power supply was not working.\u00a0 I ended up […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-2697","post","type-post","status-publish","format-standard","hentry","category-ham-radio"],"_links":{"self":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/2697","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2697"}],"version-history":[{"count":5,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/2697\/revisions"}],"predecessor-version":[{"id":2703,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/2697\/revisions\/2703"}],"wp:attachment":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2697"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2697"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2697"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}