RA-1712G
Page 2
Turn on the RA-1712G and toggle the polarity switch to the plus position. Observe the
modulator while the drive control is advanced. If the galvanometer begins to deflect in
the direction of increased track width as the drive is increased, return the polarity switch
to the standby position and reverse the modulator leads on the back of the RA-1712G.
Return the polarity switch to the plus position and continue to increase the drive control
until normal, .002" bias line(s) are achieved.
It is desirable during the setup of the RA-1712G to have a photocell or visual monitor of
the actual modulation of the galvanometer
Turn on the program switch with a 400 Hz signal applied; increase its level until the
meter on the RA-1712G in the IN mode reads 100% modulation. 100% peak-to-peak
deflection of the galvanometer should be observed. If 100% deflection is not noted,
make sure the drive control has been advanced to the point necessary to achieve the
desired bias line size and that the program switch is on. If 100% deflection is still not
observed, the RA-1712G calibration should be checked. (See section on Calibration.)
Having verified performance at 400 Hz, the next step is to adjust the internal high
frequency galvanometer resonance equalization of the RA-172G. These adjustments
are made inside the unit after removing the top plate. A nominal adjustment of the
equalization circuit has been set at the factory. However, because the characteristics of
different galvanometers vary, a readjustment may be required. Apply a signal to the
input at 8.0 kHz and observe the modulation deflection of the galvanometer. Increase
the input level until the RA-1712G meter reads 100% in the IN mode. Now adjust
trimpots R-154 and R-155 until exactly 100% modulation deflection of the galvanometer
is noted. R-154 and R-155 should be adjusted together; that is, so that the small arrows
on them point parallel to each other when the adjustment is completed.
Next, the input signal frequency is increased to 9.5 kHz and its input level adjusted to
100%. Trimpot R-180 is adjusted to achieve 100% modulation of the galvanometer.
NOTE: The RA-1712G low pass filter should be set to the 12.5 kHz position in the
above alignment procedures.
RECOMMENDED USE
The RA-1712G may be used to record 35-mm, 16-mm and 8-mm positive and negative
sound tracks. For recording 35-mm sound tracks, we recommend setting the HIGH
PASS filter to 45Hz and the LOW PASS filter to either 12.5 or 10.5 kHz. The
Equalization switch should be set to either position 1 or 2. This setting will be
determined by your experience with the amount of high frequency lost in development
and printing at the lab processing the sound track. For 16-mm recording, the HIGH
PASS filter should be set to 65 Hz and the LOW PASS to 6.5 kHz or alternatively the
HIGH PASS may be set to 85 Hz and the low pass to 6.5 kHz. The equalization switch
may be set to position 3 or 4, again depending on the laboratory which will be
developing and printing the film. Finally for 8-mm recording, the 85 Hz - 6.5 kHz filter
selections should be used with maximum film loss equalization.
