4-21
A-Chain Alignment Procedures
c. Magnetic Preamplifier Adjustments
Magnetic Alignment
7.Remove the Cat. No. 242 card and locate the reversible plug-in Magnetic Input Sensitivity header.
100mV
in
in 1V
The CP65 accepts a nominal operating input level of either 100 mV or 1V — chosen by the position of the reversible plug-in header. The input impedance of the CP65 is 100K at both input levels. In addition, some preamplifiers may require a termination resistor (usually 600 ohms). You can connect the termination resistors at the input barrier strip TB3 and TB4 "from mpu–no nr" terminals on the backplane. Note that changeover between projector 1 and projector 2 must be accomplished in the magnetic preamplifier.
If noise reduction is to be used for decoding 70 mm Dolby Stereo soundtracks, the header on the Cat. No. 242 B-chain card must be set to the 100 mV position.
If the existing non-Dolby magnetic preamplifiers are used, their compatibility with the CP65 must be ensured.
8. Re-install the Cat. No. 242 card and restore the NORMAL/BYPASS switch to the NORMAL position.
