2-13
c. If an SRA5 is currently installed using the AUX format, remove diodes D61,
D64, D65, D66, and D72 shown in Figure 2.7 with an
✗
. Add diode D67 shown
with a
✔
.
d. Reinstall the Cat.No.243 in the CP55.
ADD
ADD INSULATION
TO LEADS
REMOVE D29 & D33
BEFORE ADDING
NEW DIODES
CONTROL FUNCTIONS
INHIBITS PROJ 1/PROJ 2 PANEL INDICATOR
INHIBITS A-TYPE NOISE REDUCTION
ENABLES RECORD MODE OF CAT. NO. 222
SWITCHES CAT. NO. 222 TO ALTERNATE INPUTS
SPARE
INHIBITS SURROUND OUTPUT OF CAT. NO. 150
ENABLES STEREO DECODING ON CAT. NO. 150
'A' BIT IN INPUT SELECTION CONTROL LOGIC
'B' BIT IN INPUT SELECTION CONTROL LOGIC
'C' BIT IN INPUT SELECTION CONTROL LOGIC
INHIBITS LEFT CHANNEL OUTPUT
INHIBITS CENTER CHANNEL OUTPUT
INHIBITS RIGHT CHANNEL OUTPUT
INHIBITS SURROUND CHANNEL OUTPUT
ENABLES DECODED SURROUND IN NON-SYNC
INHIBITS OPTICAL BASS EXTENSION
✗
✗
✗
✔
Figure 2.7 Cat. No.243 Diode Modifications
6. Check for proper operation by performing the following tests:
a. Select a non-Dolby format (“01” for example). The “SR OUT” LED on the SRA5
front panel should be on.
b. Select the “05 Dolby Stereo SR” format button. The “SR IN” LED on the SRA5
should be on.
7. Run a pink noise film loop (Cat.No.69) and observe the frequency response in the
auditorium when switching between formats 04 (A-Type) and 05 (SR). Observe that
the pink noise sounds slightly louder and brighter when Dolby SR format 05 is
selected. The LEDs on the SRA5 front panel should indicate “SR IN” for the “05”
format and “SR OUT” for any other format.
2.5.1.2
Cat. No. 441 installation
The Cat. No.441 card provides the necessary right surround and subwoofer channels
along with Surround EQ. The Cat. No.441 will work in a CP55 even if the CP55 is not
modified, but will only do what a Cat. No.241 will do. To enable its full functioning as
required for Dolby Digital installations, modification of the CP55 backplane is required.
Ensure that you have good access to the backplane (rear) side of the CP55 and have
adequate light. Add leads between pins as described below. See Figure 2.8:
