Technicians Notes - Ramsey Electronics FX Series Manual

FX-223 TECHNICIAN'S NOTES
Throughout production of the "FX" series transceivers, the technicians here
at Ramsey have been speaking with customers, making repairs,
experimenting, and compiling notes on the FX-223. These notes, and the
circuit overview and theory of operation sections of your FX-223 manual,
provide extensive information on the inner workings of the FX-223. Should a
nasty gremlin jump into your trusty new FX-223, this information will help
lead your foray into troubleshooting.
Several voltages and testpoints are given throughout this guide. Keep in
mind that, due to differences in test equipment, power supply voltage, etc.,
your readings may vary slightly. Any voltage within 20% or so should be
considered ok. It may also be difficult to lead you to a specific component or
fault right off.
Now clear off that workbench, lock the doors, put up the "do not disturb"
sign, and let's get started!
Preliminary Checks: (Many times these first few checks will solve the
problem.)
1. Proper DC voltages. (+13.8VDC, +8V, +5V, +8T, +8R)
2. Solder connections. All joints should be clean, shiny, and solid. (You
won't need a magnifying glass. If a connection is suspect, reflow the
solder.) Also, check for stray solder shorts or bridges.
3. Easy to confuse items. Now let's see, was that a 10K ohm resistor
or 1K ohm? Some of those color bands look quite similar to tired
eyes. Let another pair of eyes check your work.
4. Component lead length. VERY IMPORTANT! Make sure all
component leads are as short as possible. In other words, pull the
leads through the board until the component body rests on the
board. The hand wound coils of buss wire should not touch the
board! (One exception - obviously)
5. Make sure only one channel is activated at a time. A diode installed
backwards in another channel can turn on two channels at once!
Your voltmeter should indicate voltage on only one bus wire at a
time. This is true for the offsets too.
6. Reread those sections of the manual where you feel the possible
fault could be. A thorough understanding of each circuit just may
help after all.