Dolby Laboratories CP65 - Manual (Page 30)

A-Chain Alignment Procedures
Step
No.
4-6
Indication Action
b. Optical Preamplifier Adjustments
1
2
3
Dolby
Rt
Lt
Lt
Rt
gnd
Proj. 2
hf
GAIN
hf
GAIN
Rt tp
Rt
Lt
Lt tp
Proj. 1
hf
GAIN
hf
GAIN
signal
present
Cat. No.
240A
A-Chain Alignment Procedures
Notes
4-7
b. Optical Preamplifier Adjustments
Connect the cells to the correct CP65 input terminals via the terminal block, using a single
“twisted pairs” shielded (screened) 4-conductor cable or two shielded 2-conductor cables.
Connect the inner conductors to the projector input + and – terminals exactly as shown.
Connect the shields only at the CP65 end. Note that the cell associated with the right
channel is closest to the edge of the film.
Separate cells are used for each channel in reverse scan projectors. Both use identical
red (high) and black (low) wires. A check will be made in Step 9 to determine the correct
left and right placement.
Loosely install the stereo solar cell bracket on the projector. Position the bracket carefully
until the surface of the cell is 1 mm from the film plane surface. Note that if this distance
is exceeded, there will be crosstalk between the two optical stereo tracks. Check the
image of the slit on the cell. The image should be a thin sharp line. The slit image should
be as long as the cell, and positioned three-quarters of the way up the cell. Try to get
the best compromise among all of these conditions and then tighten the cell bracket
mounting screws.
On the Cat. No. 240A Optical Preamplifier Card
Turn all of the Proj 1 and Proj 2 gain potentiometers fully clockwise (CW).