M490L — Stereo Input Module

M490L STEREO INPUT MODULE 210 cMOs dual flip-flop serving Iatch maintain the status the switches, once they have been set either the ON the OFF position number individual input functions govern the status flip-flop 210 . description each input function follows: the dua Initial Reset When ower initially applied the system, the combination CRIO CRII _ CRI2 and C38 wili pull down both ear inputs 210 until C38 fully charged thus ensuring that all solid state switches are the OFF position Channel On Momentary operation the CHANNEL ON switch SW9 wilil produce negative going pulse 21o, pin and "preset" the A-section Z1o.

Alternatively momentary ground closure the EXTERNAL CHANNEL ON control input P2, pin will resuit the same condition. Once tne flip-flop preset its output Pin changes from approximately +10 volts) This wili cause the left and cight PROGRAM switches switch ON Furthermore, 07 wil| saturate resulting the CHANNEL ON indicator lamp DS3 switch on With 07 saturated, the "control common potential appears the emitters 08 and 09 .

positive base potential is applied either Q8 09, depending on whether INPUT SELECTOR switch SwI Sw2 depressed Effectively 08 and operate similarly two AND gates The collectors the two tran- sistors represent the outputs Ihe AND gates They appear P2 , pin and These terminals are capable sinking maximum current MA each from volt source and may be used for muting purposes _ When operating the CHANNEL ON switch SW9 separate contact osed accessible P2, pins 15/s This contact may be used for imultaneous "machine start" Pin P2 isolated through diode CRL When connected parallel with the same output other modu Ies provides convenient OR gate configuration, suitable reset common timer each time CHANNEL ON button depressed 2-4

M49OL STEREQ INPUT_MODULE Attenuater Tne preamplifier output couplea via C7 one half the mixing attenuator ATTI with the second half ATTI used for the right channel The CUE channel feed taken irom the input side the attenuator. Program Channel Switch 23 cMos analog switch, serving the active switching element the left PROGRAM channe The control voltage operate 23 derived from the logi circuitry within the module and coupled 23 via CR2 To switch the channel ON, this control voltage tne order volts.

When the control voltage drops volts, the swi tch will be OFF resulting signal attenuation more than 100 dB The control voltage used operate 23 also fed into the right channel circuitry via pin E5 on the 7-112A card Booster_Amplifier Following 23, the signal amplified by integrated circuits and 25 nominal level dBm (equivalent voltage) and routed the PROGRAM ASS GN switches SWL and SWS, via BALANCE switch SW3 and BALANCE control R42 R45 Due the dB insertion Ioss the BALANCE control .

the signai level the input SwL and SWS dBm (equivalen voltage) . the right channel the gain fixed result dBm output by insertion jumper wire on PCB 7-112A . The left channel contains tne LEVEL BALANCE control R31 which used match the level the left channel the right channel R3I factory set and should require no further adjustment Unequal level balance would normally be corrected by adjustment the SENsiTivity trim controls RIO and R135 _ The mixing attenuator ATT should be placed the dB "in hand" position make this adjustment_ Program Quteuts Switch Sw3 serves insert the BALANCE control R42 R45 into the signal paths Operation this control permits raising the level one the stereo channels while reducing the Ievel the other 2-2

M49L STEREO INPUT_MODULE The ON status driven by 06 _ the CUE channels indicated by DS2, which Cut_Off An dditional feature ensures tha the CUE channels will always switcn OFF whenever the slide attenuator moved onto way from the infinite" position, regardless their prior state The control signal for this action initiated by the change state the ATTENUATOR cuT switch SW10.

The resultant Ievel change being either positive negative going, processed through 29, 21i and 212. The output produced pin 212 wili always be negative going pulse approximately 500 milliseconds duration. CRI3 passes this pulse 21o, pin thereby "clearing" the B-section the flip-flop and resulting pin 210 switch (or remain at) vol - t5, turn switching the Ieft and right CUE switches OFF AI logic control inputs are buffered and switch bounce guard against spurious noise Power Supply Decoup_ Jing Power supply decoupling provided by R131 R134 and C48 C51 CRI7 and CR18 serve prevent amplifier damage the event supply voltage reversa The ecoupling network drops the +/-25 velt supply rails nominal voltage +/-18 volts.

010 decouples and ters the positive supply rail, resulting an outpu: +12 volts operate the cMOS circuitry Tn addition _ 24 and 25 are further decoupled +/-16 volts by R36 , R37 C17 and C18 Separate on-board power supply decoupling provided on the 7-112A printed circuit board 2-6

ML9OL STEREQ INPUT_MODULE Input Sensitivity: -10 +10 dBm (ref . 600 ohm source} Frequency Response: +/-0.5 dB from 30 Hz t0 20 kHz Noise: dB below nominal operating Ievel with mixing attenuator set dB "in-hand" (20 Hz 20 kHz} . Harmonic Distortion: Less than 259 THD from Hz kHz dB above nominal operating level Less than 1% at kHz 20 dB above nomina operating Ievel .

Less than 0 .59 at kHz through cue channel dB above nominai operating Tevel Source Impedance: 600 ohms less, balanced. Input Impedance: 0o0 ohms Output Impedances: 0o0 ohms balanced (program circuits) 60,000 ohms balanced cue circuits) 00o ohms, balanced (post direct) Output Level dBm nominal, +20 dBm max mum. Channel Separation: Better than dB irom 150 Hz 15 kHz Phasing: Input and output terminals designated by numbers are in phase; lower number numbered pair phase with Tower number other numbered pair Logic Input Levels: (To operate CH ON, ch OFF CUE ) Logic Logic +13 voits +16 +24 volts_ External Control Output: (Open collector current sink)

M49OL STEREQ INPUT MODULE Minimum Ioad impedance: Maximum Ioad current: Maximum supp voltage: Saturated collector voltage: 600 ohms 40 MA. +24 volts_ volts maximum 40 MA load. Power Requirements: +/-25 volts dc, MA maximum MA nominal_ Ambient Temperature: degrees Celsius Dimensions: wide 14.15" high (41 Mm 360 mm 165 Mm ) deep

M490L STEREO INPUI_MODULE PART DESCRIPT ON MFG MFG PARI_NUMBER R16 RI7 R18 R19 RzO Resistor 1/4w 5% 4K7 20k 3K3 39k IM Philips R21 R22 R23 R24 R25 IM L70k 2K2 2k2 100K R26 R27 R28 R29 R3O 220k 10k 15k 47k ISK R31 R32 R33 R34 R35 Trim Pot Resistor 1/Lw 59 20k 620 15K 15k 620 Piher Philips PT 1Ov 20k R36 R37 R38 R39 R4Q 390 390 K R41 R42} R43 R4L R45) Potentiometer A/B WBS 10-017 R46 RL7 RL8 R49 RSO Resistor 1/4w5% IKB 1KB IK8 IK8 10K Philips 3-4