{"id":3389,"date":"2024-01-27T07:20:50","date_gmt":"2024-01-27T15:20:50","guid":{"rendered":"https:\/\/philcoradio.com\/library\/?page_id=3389"},"modified":"2024-02-25T09:17:53","modified_gmt":"2024-02-25T17:17:53","slug":"philco-model-38-690-repairs-part-7","status":"publish","type":"page","link":"https:\/\/philcoradio.com\/library\/index.php\/shop-talk\/rons-radios\/philco-model-38-690-repairs-part-7\/","title":{"rendered":"Philco model 38-690 Repairs \u2013 Part 7"},"content":{"rendered":"

\"A<\/p>\n

I left you last time at the point where I had removed the 37-116 oscillator switch assembly from the trimmer condenser unit. At that point, some wires still needed to be unsoldered from the switch assembly.<\/p>\n

When I resumed working on this, the first thing I did was to unsolder and remove those remaining wires. Next, the switch assembly itself was disassembled, leaving the individual switch wafers.<\/p>\n

I cleaned each switch wafer with 99% isopropyl alcohol. You can see in the image above that the amount of dirt and grime on each wafer turned the alcohol a light brown. It left the switch contacts nice and bright, though.<\/p>\n

\"A<\/p>\n

Next came reassembly of the switch wafers into a complete switch assembly. Having carefully kept track of which wafer went in what order, this was not that difficult to do.<\/p>\n

Before long, the assembly was back together again and ready for reinstallation of the coils, wires, and other components.<\/p>\n

\"A<\/p>\n

I began reinstalling the coils, beginning with the Band 1 oscillator coil. This was slow, tedious work. The drawing I had made previously showing how things connect between switch wafers for this section (see Part 6<\/a> for details) was a big help.<\/p>\n

\"A<\/p>\n

After some more slow, careful work, all five coils were back in place. I made sure each coil had good continuity before, and again after, it was mounted in place.<\/p>\n

\"A<\/p>\n

Next came the attachment and soldering of more wires, as well as some resistors and capacitors.<\/p>\n

\"A<\/p>\n

Eventually, I reached a point where I felt it was ready to reattach to the part with the trimmer condensers. Unfortunately, here is where I ran into some trouble. I had failed to document which wire attached to what point on the trimmer condenser assembly. Fortunately for me, I had another 37-116 chassis out in the garage. I brought it in, studied it carefully, and made myself yet another road map or \u201ckey\u201d as follows:<\/p>\n

\"Diagram,<\/p>\n

The text in red indicates where each terminal connects.<\/p>\n

Armed with this information, I set about to straighten out the wiring of the trimmer condensers. I had managed to wire every one wrong, so every wire had to be removed from the trimmer condenser assembly and redone.<\/p>\n

As I did all of this, I managed to break a coil wire. It was the Terminal 1 wire from part (37), the AM oscillator coil. After panicking for a bit, I calmed down and then managed to repair the coil by carefully adding another wire to it, and sealing the area with hot glue.<\/p>\n

A careful check afterward with my multimeter indicated that the repair was successful. At least the coil had good continuity between Terminal 1 and each of the other four wire terminals.<\/p>\n

\"A<\/p>\n

Now that the oscillator section was mostly back together, I continued to add some more components to the switch assembly.<\/p>\n

\"A<\/p>\n

The next thing I did was to reattach the oscillator section to the sub-base. By now I felt that I could finish wiring things up in this section later.<\/p>\n

\"A<\/p>\n

That is far as I am going to go with this for now. It is time for me to begin working on my Christmas radio project \u2013 this year, a Fisher FM-200 tuner \u2013 and set this aside for a while.<\/p>\n

I will resume work on this sometime after the first of the year. Stay tuned as I will finish wiring up the oscillator section, and then add the converter or RF section and then the antenna section, in that order, to the sub-base. Once everything is back together, it will be time to try it out in the 38-690 chassis.<\/p>\n

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

I left you last time at the point where I had removed the 37-116 oscillator switch assembly from the trimmer condenser unit. At that point, some wires still needed to be unsoldered from the switch assembly. When I resumed working on this, the first thing I did was to unsolder and remove those remaining wires. […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2599,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-3389","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/pages\/3389","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/comments?post=3389"}],"version-history":[{"count":2,"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/pages\/3389\/revisions"}],"predecessor-version":[{"id":4908,"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/pages\/3389\/revisions\/4908"}],"up":[{"embeddable":true,"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/pages\/2599"}],"wp:attachment":[{"href":"https:\/\/philcoradio.com\/library\/index.php\/wp-json\/wp\/v2\/media?parent=3389"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}