3M DELTA Series - Repeat Play Lockout; Reproduce Output Mpedance; Balanced Transformerless Output

'NOTE: When both REC and PLAY meter switches
are simultaneously depressed, the metering
circuits will "default", and indicate the same
meter function indicated when only the REC
switch is depressed.
F. OPERATIONAL OPTIONS
Delta Series units may be operationally config 
ured to perform various tasks depending on your
specific needs. Special functions are outlined below:
1. READY LAMP FLASH — The ready lamp may be
programmed to flash, giving a visual indication
of a cartridge that has been stopped. A fast flash
indicates a cartridge that has been stopped by
the operator using the Stop Switch. A slow flash
indicates a cartridge has stopped by the 1 kHz
cue tone. When units are programmed to flash,
the flashing Ready may be "reset" to continuous
Ready by momentarily pressing the Stop switch.
This jumper is located on the Reproduce Logic
Board.
Jumper Flash Option
"IN" Not Active
"OUT" Active
2. REPEAT PLAY LOCKOUT — This programmable
option inhibits playing the same cartridge
twice in a row. In other words, once a cartridge
has played and stopped, it may not be restarted
until it is removed from the deck, and reinserted.
This prevents replay of the same program mate 
rial. This jumper is located on the Reproduce
Logic Board.
Jumper Repeat Play Lockout
"IN" Enabled
"OUT"Disabled
3. E.O.M. HIGH SPEED RECUE — May be jumpered
so that neither, either, or both the secondary
(150 Hz) and tertiary (8 kHz) cue tone detectors
cause the end-of-message high speed recue to
occur. This jumper is located on the Play Amp
and Cue Detector Board.
4. REPRODUCE AMPLIFIER LEVEL — Provides out 
put level range for preservation of best signal-
to-noise.
5. REPRODUCE OUTPUT IMPEDANCE — 600 ohms,
balanced transformer is standard. Refer to
mainframe schematics for information regard 
ing 150 ohm balanced.
6. BALANCED TRANSFORMERLESS (ACTIVE) OUT 
PUT — All Delta Series units may be operated in
a transformerless (active) output stage configu 
ration for improved transient response. The high
slew rate of the output stages may be utilized to
provide the best possible audio response, in par 
ticular at the extreme ends of the audio band.
When output transformers are removed,
DC isolation between the Delta output stage and
connected equipment should be maintained.
This is accomplished by inserting a 220 mfd non 
polarized capacitor in each output leg, (+) and
(-). ITC provides an assembly to readily convert
any Delta Series output to balanced transformer 
less.
Delta I. II Audio Output Board
831-0252-003
831-0252-013
831-0252-023
831-0252-033
Mono, w/transformer
Stereo, w/transformer
Mono, w/o transformer
Stereo, w/o transformer
Delta III Audio Output Board
831-0254-003
831-0254-013
831-0254-023
831-0254-033
Mono, w/transformer
Stereo, w/transformer
Mono, w/o transformer
Stereo, w/o transformer
7. RECORDER INPUT IMPEDANCE — 20 K ohms
bridging is standard. The input may be termi 
nated by a 150 ohm or 600 ohm resistor by
adding a jumper to each input channel. The
D-IV mainframe has this jumper already in
place. Refer to the Delta IV input transformer
board drawings for exact location.
8. INPUT LEVEL STRAPPING — Input straps are pro 
vided to select the nominal input level range, to
insure best overall signal-to-noise is preserved,
and to set the nominal position of the front panel
level controls. Jumpers are located in the Delta
IV mainframe.
9. DIFFERENTIAL (TRANSFORMERLESS, BALANCED)
INPUT — Input transformers (standard) may be
removed in order to operate the Delta IV record
amplifier in a true differential input configura 
tion. High performance op-amp record ampli 
fier input sections permit this user option. When
operating in the differential input mode, users
should be cautious to insure that no DC poten 
tial, or AC ground loops exist before attempting
connection. Removal of the input transformer
eliminates the DC protection characteristics (iso 
lation) offered by the transformer. Once the
transformers have been removed, wire jumpers
2-8