This verbal description will be broken up into smaller pieces to make it easier to follow. The left and right channels are identical and the left channel will be described. The right channel will only be mentioned where differences exist. Part one. The phono preamplifier. An RCA type phono jack is labeled J101, left magnetic phono input. The shell of the jack connects to ground. The center connects through R100, a 1 k ohm resistor to R101, a 47 k ohm resistor, the other end is grounded. The junction of R100 and R101 connects to the grid, pin 7 of V101 a 12 A X 7. The cathode, pin 8, of this half of V101 connects through R 102, a 3.3 k ohm res to ground. We will return to pin 8 later. The plate, pin 6 connects through R103 a 470 k ohm res to B plus 3. Pin 6 also goes through C101 a .01 mike cap to the other grid, pin 2, of V101. Pin 2 goes to ground through R104 a 6.8 meg ohm res. The cathode of this section, pin 3 is grounded. The plate, pin 1 goes through R105 a 220 k ohm res to B plus 3. Pin 1 also goes through C102 a .1 mike cap to point A. Point A goes through R106 a 3.3 meg ohm then through R107 a 100 k ohm in series to pin 8 of V101. In parallel with R106 is C103 a .0033 mike cap. In parallel with R107 is C104 a 750 pf cap. Point A also connects to the positive side of C105 a 1 mike 25 volt electrolytic cap. The negative side goes through R108 a 4.7 meg ohm res to ground. The junction of C105 and R108 goes through a shielded cable to the phono-left position of S1, source switch. Part two. Source selector switch through balance control. The phono right position of S1 goes to the junction of C205 and R208. The auxiliary left position goes to the center of J102. The auxiliary right position goes to the center of J202. J102 and 202 are the left and right auxiliary inputs. Their shells go to ground. The left swinger of S1 goes to the top, clockwise, end of P1L, dual 500 k ohm, audio taper volume control. The CCW end is grounded. The wiper of the control goes through R109 270 k ohm to the grid, pin 2, of V1L, one half of a 12 A X 7. There is a cap, C106 .001 mike in parallel with R109. The cathode, pin 3, goes through a 1.8 k ohm res to ground. The plate, pin 1 goes through R111 a 270 k ohm to B plus 2. Pin 1 also goes through C107 a .1 mike cap to tone in. The tone in point goes through R112 a 120 k ohm res to the CW end of P2L, a dual 500 k ohm audio taper Bass pot. The CCW end goes through R113 a 27 k ohm res to ground. C108, a .0018 mike cap connects from the CCW end to the wiper of P2L. C109, a .015 mike cap connects from the CW end to the wiper. The tone in point connects through C110 a 750 pf cap to the CW end of P3L, dual 500 k ohm audio taper treble control. The CCW end connects through C111 a .0033 mike cap to ground. The wiper of P3L connects to the wiper of P2L. The two wipers go to one end of R114 a 120 k ohm res. The other end of R114 goes to the CCW end of P4L, dual 250 k ohm linear balance control. The CW end goes through R115 a 120 k ohm res to ground. In the right channel the wipers of P2R and P3R go to one end of R214 120 k ohm. The other end of R214 goes to the CW, not CCW, end of P4R. The CCW end goes through R215 a 120 k ohm res to ground. Part three. Post balance control section. The wiper of P4L, the balance control goes to pin 2, grid, of V2L, one half 12 A X 7. This is the only connection to pin 2. Pin 3, cathode goes through R116 a 3.9 k ohm res to ground. We will return to pin 3 later. The plate, pin 1, goes through R117 a 270 k ohm res to B plus 2. Pin 1 also goes through C112 a .0022 mike cap to the grid, pin 2 of V3L, one half 12 A X 7. That's no mistake; that's a .0022 microfarad cap. Pin 2 of V3L goes through R118 a 470 k ohm res to ground. Pin 3, cathode of V3L goes through R119, a 3.9 k ohm res to ground. Pin 1, plate, goes through R120 a 270 k ohm res to B plus 1. Pin 1 also goes through C113 a .1 mike cap to pin 2, grid, of V4L, one half 6 C G 7. The cathode, pin 3, of V4L goes through R 123, 510 ohm then R122, 1 k ohm to ground. R 121, 1 meg goes from the junction of R122 and R123 to the grid, pin 2, of V4L. The plate, pin 1 connects to B plus 1. Pin 3 of V4L also goes to the positive side of C114 a 470 mike 25 v cap. The negative end connects to point B. Point B connects through R125 a 36 k ohm res to the negative end of C115 a 22 mike 25 v cap. The positive end goes to pin 3 of V2L. In parallel with R125 is C116 a 33 pf cap. Point B also goes through R124 a 100 ohm, then R 126 a 1 k ohm to ground. The junction of R124 and R126 connects to the tip contact of a one quarter inch stereo phone jack J1. The ring contact of J1 connects to the junction of R224 and R226 in the right channel. The sleeve contact of J1 goes to ground. Part four. Power supply primary. The wide prong of a polarized 120 V A C line plug goes to one side of the primary of T301 and one side of the primary of T302. The narrow prong goes through a fuse, F301, 1 amp, then the on/off switch, S301 to the other sides of both primaries. The two primary windings are connected in parallel. Part five. High voltage and AC heaters. T301 has a 500 volt center tapped and a 6.3 volt winding. The center tap of the 500 V winding is grounded. Connected from one end to the other is an optional capacitor C308 a .0022 mike 3 kV disk ceramic cap. The top end connects to the anode of D301 and the bottom to the anode of D302, both 1N4007, 1 amp 1000 volt silicon diodes. The cathodes of the diodes connect together and to R301 a 470 ohm 1 watt res. The other end of R301 connects to the plus side of C301. This point connects through R302, 1000 ohm 1 watt to the plus side of C302. This point is labeled B plus 1. R303, a 6.8 k ohm res connects from B plus 1 to B plus 2. B plus 2 also connects to the plus side of C303. R304, a 47 k ohm res connects from B plus 2 to B plus 3. B plus 3 also goes to the plus side of C304. The negative sides of C301 through C304 go to ground. C301 through C304 are 47 mike 350 V electrolytic caps. One side of the 6.3 volt winding goes to pin 4 of V4, and pin 9 on V2 and V3. The other side of the 6.3 v winding goes to pin 5 on V4 and pins 4 and 5 on V2 and V3. Two 150 ohm resistors R 305 and R306 are connected in series across the 6.3 v winding. The junction of R305 and R306 goes through R308 an 8.2 k ohm to ground. The junction also goes to the positive side of C305 a 10 mike 25 v cap. the other end is grounded. The junction also goes through R307 a 100 k ohm 1 watt res to B plus 1. Part six. DC heater supply. T302 is a 25.2 volt 1 amp transformer. The two ends of the secondary winding are connected to the AC inputs of a standard bridge rectifier made up of D303 through D306. A 100 v 1 Amp unit can be used or use 4 1N4002 diodes. The negative terminal of the bridge is grounded. The positive terminal goes to the positive end of C306, 2200 micro farad 50 volt electrolytic capacitor. The negative end of C306 goes to ground. R309, 4.7 k ohm one half watt is in parallel with C306. If the transformer you are using has a center tap cut the lead off and slip a piece of sleving over the end to make sure it doesn't short out. A center tapped transformer is not required. The positive end of C306 goes to pin 4 of V1. Pin 5 of V1 goes to pin 4 of V101. Pin 5 of V101 goes to pin 4 of V201. Pin 5 of V201 is grounded. End verbal description.
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