IC-201_Restoration_DL7MAJ_2018.pdf

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1、Jan. 6th 2018 Page 1 of 9 Restoration of an ICOM IC-201 2m Allmode Transceiver from the “Seventies” IC-201 after successful restoration This report describes my experiences with an old IC-201, which I bought via an auction in the web. The seller promised some bugs and indeed the IC-.201 had not only

2、 these promised bugs but many more; so I got more than I had paid for. In general: When buying an old rig, always expect the worst possible case and be happy if its better! So the biggest bugs where: 1. Deaf receiver: above 100V for good reception in all modes 2. Output less than 100mW in all modes

3、3. No Squelch, no ALC 4. Intermitted operation, crackling and noisy sound Some hints are available in the net /1/ and one of the most culprits seems to be the so called mainboard. There are many feedthrough pins which have a horrible quality and tend to fail over the years. In general, contacts are

4、the biggest problem in the IC-201. In this project, I had no faulty elements only bad contacts! Jan. 6th 2018 Page 2 of 9 If you have an IC-201 with problems, always do this first step: Remove ALL boards and the front panel; you have to unsolder only one coax-connection on the premixer board. All ot

5、her connections and boards are plugged. Premixer Board Unsolder coax wire for removal Jan. 6th 2018 Page 3 of 9 Removed boards Then you have access to the mainboard on the bottom and can fold it out carefully: Jan. 6th 2018 Page 4 of 9 Mainboard folded out Ground connection improvements The ground c

6、onnections between some areas of the mainboard are made via the chassis and screws, which is very bad due to aging and corrosion. Jan. 6th 2018 Page 5 of 9 In the second step improve ground connections: - Solder three ground wires between the areas - Connect both sides of ground layers with small co

7、pper strips - See above picture with red arrows Third step: Feedthrough pins: These are the most reasons for problems, because they are very poor! Example for bad feedthrough pin They are made with small pins which tend to loose contact over the years. Best is to remove ALL feedthrough pins and repl

8、ace them by wires: Some old pins and new wires can be seen in this picture this work is worth to be done! Jan. 6th 2018 Page 6 of 9 Fourth step: All pinheads Another culprit are the pinheads on the mainboard and their connections. All swimming on solder flux? The layout of the AF-Board isnt very goo

9、d related to ground wires; so additional wires are recommended. The small pinheads need also special attendance. Critical small pinheads on the AF-board Jan. 6th 2018 Page 7 of 9 Additional ground wires (green) and resoldered pinheads on the AF-Board Jan. 6th 2018 Page 8 of 9 Fifth step: All plugged

10、 connections Boards with plugged connections can easily be removed but over the years they may degrade. Check ALL plugged connections; for coax connectors also check the center conductor! Clean/deoxit them and bend the counter contact back into the right position if necessary. These bad plugged conn

11、ections on the TX-Mix board caused low output The deaf receiver was caused by bad coax connectors in the RF-Unit Jan. 6th 2018 Page 9 of 9 Finally, the plug of the power supply was bad: Caused sometimes a total blackout of the transceiver Sixth step: Replace all bulbs with LEDs Used white, red and g

12、reen LEDs with series resistors to replace all bulbs. Seventh step: READY After this work was done, the IC-201 worked very fine and a realignment was done; more details on my website /2/ /1/ http:/www.pa0ply.nl/icom_ic-201.htm /2/ http:/www.dl7maj.de/ICOM.html If you want to contact the author: Stefan Steger, DL7MAJ, eMail: dl7majt-online.de Homepage: www.dl7maj.de