3M DELTA Series - Meter Calibration

ence tone (160 nWb/m) used on the 1975
NAB standard alignment tape.
c. It cue level adjustment is required, turn trim 
mer R1231, located on the Recorder Logic
Control PC Board, until the Primary cue tone
is equal to the NAB standard reference tone
of 1 kHz at 160 nWb/m.
NAB Cue Tone Level Standards (1976)
Referenced to 160 nWb/m
Nominal
Minimum
Maximum
1 kHz 0
-3
+ 1
150 Hz +6
+3
+7
8 kHz -10
-13
-9
d. Return the left program playback and cue
playback head cables back to their original
locations.
6. Meter Calibration
The following adjustments are made with multi
turn potentiometers located on the Record/Me-
ter Amp PC Board. Potentiometers are identified
on the small sticker applied to the underside of
the top cover (lid).
a. Program Play
— Select the PLAY meter switch position.
— Connect a 600 ohm load across the left or
mono program playback output terminals.
— Insert and play an NAB standard reference
level tape (1 kHz at 160 nWb/m recorded
level — 1975 standard). Adjust R10 19 for a
0 VU indication.
— Repeat this procedure for the right channel
if the machine is stereo. Use R1015 for cali 
brating the right PGM Play meter for 0 VU.
b. Normal Record
— Select the PGM PLAY meter switch position.
— Place the machine into the recording mode.
— Select the REC meter switch position and
observe the level(s).
— Use R1022 to obtain a 0 VU indication for
the left channel (mono).
— Use R10 18 to adjust the right meter to read
0VU.
c. Program Bias
— Select the PGM Bias meter switch.
— Insert an erased cartridge, press REC and
START.
— Adjust the left channel (mono) program
bias trimmer R1020 for a 0 VU reading on
the left channel meter.
— Repeat this same procedure for the right
channel using trimmer R10 16.
d. Cue Bias'
— Select the CUE BIAS meter switch.
— Insert an erased cartridge and press START.
— While pressing and holding the TER (ter 
tiary) cue switch, adjust potentiometer
R10 17 for a 0 VU reading on the front
panel meter (right meter).
e. Cue Play'
— Select the CUE PLAY meter switch.
— Insert and erased cartridge tape and press
START.
— Press the 1 kHz CUE REC switch. A meter
deflection for approximately 3/4 of a sec 
ond in length will be observed. The point
at which the meter settles in the last 1/4
second is the point at which 0 VU should be
calibrated.
— Adjust R1021 to calibrate the Cue play
metering to read 0 VU.
'NOTE: Since the Delta IV features combina 
tion metering of Cue Bias and Cue Play, pay
particular attention to Cue Bias indication on
one meter, simultaneous with Cue Reproduce
levels indicated on the other. Refer to the
metering chart in Section II for details.
5-3