Philips FM92E, Manual

Page: 27 / 86

1: Remove the VCO block from the Receiver board by de-soldering the pins and removing the 2 screws. Use a
solder sucker or solder wick if you do not have access to a de-soldering station, then ensure that all the
solder is removed and the holes in the board are clean (this makes it easy to refit later). The club has a de-
soldering station, you will be trained in how to use it during one of the Tuesday night sessions. Be very, very
careful of this operation, you can easily break the pins from the module to the “Receiver PCB” – Be
care-full .
You may have to heat the pins up that are holding and gently pry module, this is a three hand job.
There will be two de-soldering irons at the club rooms, the Rovel De-Soldering station and a Single Shot De-
Soldering iron. If you can use the Single Shot De-Soldering iron to remove solder from the non-earth pins
and, the Rovel De-Soldering station de-soldering iron for the earth connections of the VCO module. This will
enable two users at a time to be de-soldering.
Firstly, use a wooden tooth pick [supplied by the club] to drop VK2ZAD Bruce’s Bug Juice onto each pin to
be de-soldered.
When you have removed the VCO module, with an old tooth brush, clean the Receiver PCB with methylated
spirits. Then, make sure that the VCO ceramic PCB pin holes are clear; if they are not then de-solder them
clear. Then re-brush with methylated spirits.
Note the IF frequency [21.4MHz] in the photo above.
2: Once the module is free of the board, put the radio to the side for the time being and concentrate on the VCO.
Using a large soldering iron, you need to remove the cover of the VCO. The cover is removed by heating the
case along the join and gently prying off the cover whilst ensuring it is not distorted too much, as it needs to
be re-sealed later. With the soldering iron on the side of the panel, use a scalpel, small screwdriver, etc, to lift
the side panel.
NOTE: Too much heat and you can unsolder components on the ceramic board, inside of the VCO module.
Or , a better method is to score the solder on four sides of the VFO block with a scalpel; then remove the four
sides by prying with the side of the scalpel or a very small screwdriver. As you score the sides, watch your
fingers. The scoring causes small slivers of solder to be formed, dispose of these slivers as soon as possible.
Philips FM92E Conversion to 6 Meters: Version 3.9 Page
27