Ramsey Electronics FZ-146 Specifications download pdf (Page 139)

FX-146 • 139

FX-146 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-146. These notes, and the

circuit overview and theory of operation sections of your FX-146 manual,

provide extensive information on the inner workings of the FX-146. Should a

nasty gremlin jump into your trusty new FX-146, 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

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Ramsey Electronics FZ-146 Specifications Page 139