Studio Technologies ISS - Manual (Page 38)

ISS User Guide Issue 3, June 1990
Studio Technologies, Inc. Page 39
ISS
Adjusting the Compressor
1) Move AC voltmeter lead to test point
TP4. Note the reading that you observe.
It should be –10 ±2.5dBu.
2) Reduce generator output level by 20dB.
Note: This means drop the level by
20dB.
3) Observe level at TP4. It should have
dropped 15 ±0.3dB. If not, adjust R69
to get this condition.
4) Raise generator level 20dB. Observe
level at TP4.
5) Reduce generator output level 20dB.
Observe level at TP4. It should drop 15
±0.3dB. If not, again adjust R69 to get
this condition.
Adjusting the Analog Delay for Minimum
Distortion
1) Set generator frequency to 5kHz; adjust
level to give –10dBu when measured at
TP3.
2) Connect distortion analyzer to measure
at TP1.
3) Adjust R18 to give minimum distortion
(THD + Noise). The acceptable mini-
mum distortion is 0.35% or lower. The
usual minimum is 0.25% to 0.10%.
Adjusting the Expander
1) Set generator frequency to 1kHz; adjust
level to give –10dBu when measured at
TP3.
2) Measure level at TP1.
3) Drop generator level 20dB. Level at TP1
should drop 20 ±0.3dB. Adjust R56 to
get this condition.
4) Raise generator level 20dB. Observe
level at TP1.
5) Drop generator level 20dB. Observe
level at TP1. It should drop 20 ±0.3dB.
If not, again adjust R56 to get this
condition.
Adjusting the Transient Response of the
Expander
1) Adjust generator level to give 0dBu
when measured at TP3. Set the genera-
tor to tone burst mode: two cycles
open, 64 cycles closed. In this way, two
cycles of audio pass to the ISS, then
64 cycles of no audio, etc.
2) Observe TP1 on the oscilloscope.
Adjust R4 to give the flattest base band
signal. The signal should not over or
under shoot.
3) This completes the entire procedure.
Procedure for Type II Card
1) Temporarily remove op amp U9. Use
jumper clip to connect TP4 to the top
of resistor R63. Refer to schematic to
see that you have removed the band
dip filter from the circuit. This makes
alignment much easier.
2) Place the Type II Simulator Card onto
the Extender Card Assembly. Refer to
the Technical Notes section of the ISS
Technical Manual for Extender Card
installation details.
3) Turn the ISS mains power on.
4) Set the ISS to: I/O Normal, mode to
MAN, SIM LEFT.
5) Set R4 and R43 to 50% clockwise; R18
to 75% clockwise.