Maintenance And Repair - Wavetek Meterman FG2C Operator's Manual

PRECAUTION ITEMS
(1) The DC OFFSET (11) knob, will provide a DC level voltage of ±10V (no load) or ±5V (50Ω load). However, the signal
amplitude plus the DC level, is limited to ±20V (no load) or ±10V (50Ω load). In case of over voltage, clipping will appear as
show n in Figure 6.
(2) The main OUTPUT terminal is calibrated into a 50Ω load. This indicates that the signal source impedance is 50Ω. The OUTPUT
terminal may be connected to any circuit input impedance, but output the voltage and terminal impedance will not be calibrated.
To avoid oscillation, the OUTPUT terminal should be connected to a 50Ω load (especially when using high frequency and square
wave output), and the connecting cable should be as short as possible.
(3) When the DUTY knob is full counterclockwise, the ratio of positive state to negative state, should not be less than 80:20. When
the DUTY knob is full clockwise, the ratio of positive state to negative state, should not be greater than 20:80. Square waves can
be expanded to pulse waves, triangle waves can be expanded to ramp waves, sine waves can be expanded to unsymmetrical sine
waves. The Figure 7 shows the effect of the DUTY control adjustment on different waveforms.
Figure 6
A. Zero DC Offset
with Maximum Signal
B. Offset Limit
without Clipping
C. Excessive Offset
All examples:
Output terminated
is 50 ohm
FUSE REPLACEMENT (See Figs. 2 and 4)
Preliminary: Disconnect test leads from circuit and Function Generator. Push Power Switch off and unplug the power cord from the
rear of the Function Generator.
Warning:
Failure to turn off and remove power from the Function Generator before changing the mains power
fuse could result in damage to the instrument and the operator.
Fuse replacement: Remove the fuse by inserting a small flat blade screwdriver into the notch at the bottom of the mains power
connector socket. Slide the fuse holder out. Replace the fuse with one of the following:
115 VAC 50/60 Hz: T0.315A/250V fuse (5mm x 20mm), I.R. 100kA – Wavetek p/n 2400-05-0069, Littel Fuse p/n 218.315, or
Bussmann p/n. GDC-315mA.
230 VAC 50/60 Hz: T0.160A/250V fuse (5mm x 20mm), I.R. 100kA – Wavetek p/n 2400-05-0070, Littel Fuse p/n 218.160, or
Bussmann p/n. GDC-160mA.
Warning: Use only an equivalent fuse to the one specified. Use of an incorrect fuse could result in serious injury or even death.
Reassembly: Slide the fuse holder back into the fuse cavity and reconnect the power cord.
MAINTENANCE & REPAIR
If there appears to be a malfunction during the operation of the Function Generator, the following steps should be performed in order
to isolate the cause of the problem:
test the Test Cables for a broken or intermittent connection.
replacement of the fuse, or test cables, repair of the Function Generator should be performed only by a Factory Authorized Service
Center or by other qualified instrument service personnel. The front panel and case can be cleaned with a mild solution of detergent
and water. Apply sparingly with a soft cloth and allow the function generator to dry completely before using. Do not use aromatic
hydrocarbons or chlorinated solvents for cleaning.
POSITIVE NEGATIVE
DC OFFSET DC OFFSET
POSITIVE NEGATIVE
DC OFFSET DC OFFSET
POSITIVE NEGATIVE
DC OFFSET DC OFFSET
Review the operating instructions for possible mistakes in operating procedure.
Figure 7
VARY THE DUTY OF SHORTER TIME SECTION BY
ADJUSTING THE FREQUENCY ADJUSTMENT DIAL
VARY THE DUTY OF LONGER TIME SECTION BY
ADJUSTING THE DUTY CONTROLLER
Inspect and test the fuse. See Fuse Replacement. Except for the
- 8 -
PULSE
(SQUARE WAVE)
RAMP
(TRIANGLE WAVE)
UNSYMMETICRAL
(SINE WAVE)
TTL CMOS
Inspect and