User manual MCINTOSH MX135 SERVICE MANUAL B

[. . . ] 42 - 47 Video Schematic and PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 - 50 Input Schematic and PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 - 56 Component Video Schematic and PCB . . . . . . . . . . . . 57 - 60 Tuner AM/FM Alignment Procedure . . . . . . . . . . . . . . . . . [. . . ] A high impedance (10 megaohm) voltmeter must be used. 3. On PC board drawings, Square pad indicates: a. WARNING Parts marked with the symbol have critical characteristics. Use only replacement parts recommended by the manufacturer. REAR PANEL 3 SECTION LOCATIONS TOP VIEW WITH COVER REMOVED BOTTOM VIEW WITH COVER REMOVED 4 MX135 BLOCK DIAGRAM 5 6 BLOCK DIAGRAM con't 7 8 1 INTERCONNECT MX135 9 10 11 2AC B DISPLAY 050036 SH 1 OF 2 12 13 14 MX135 2AC B DISPLAY 050036 SH 2 0F 2 15 16 17 2A DISPLAY CONTROL SECTION 050036 3 SURROUND 050037 SH 1 OF 6 2B LED SECTION 050054 2C KEYBOARD SECTION 050053 18 19 20 MX135 3 SURROUND 050037 SH 2 OF 6 21 22 23 3 SURROUND 050037 SH 3 OF 6 24 25 26 MX135 3 SURROUND 050037 SECTION 4 OF 6 27 28 3 SURROUND 050037 SH 5 OF 6 29 30 MX135 3 SURROUND 050037 SH 6 OF 6 31 32 3 SURROUND 050037 33 34 MX135 NOTES 35 36 4 DATA 050033 SH 1 OF 2 37 38 MX135 4 DATA 050033 SH 2 OF 2 39 40 41 5 S-VIDEO 050035 SH 1 OF 2 42 43 44 MX135 5 S-VIDEO 050035 SH 2 OF 2 45 46 47 6 VIDEO 050034 48 49 50 MX135 7 INPUT 050032 SH 1 OF 2 51 52 53 7 INPUT 050032 SH 2 OF 2 7 INPUT 050163 54 55 56 MX135 8 COMPONENT VIDEO 050039 57 58 59 TUNER ALIGNMENT PROCEDURE Note: Refer to Figure 1 while reading the below procedure. FM ALIGNMENT PROCEDURE 1. Connect an FM Signal Generator to Antenna Input. Connect Distortion Analyzer to the TUNER IN/OUT RCA jacks. Press the red Standby button to turn the unit On. Select Tuner with the Zone A selector knob. Put Tuner into FM mode and tune to 87. 5MHz. Adjust L5 (FM OSC Coil) for 3. 5VDC at R46. Tune to 108. 5MHz and adjust C59 (FM OSC Trimmer Capacitor) for 24. 5VDC at R46. Repeat steps 4, 5 and 6 as necessary for a tuning range of 3. 5VDC to 24. 5VDC at R46. Tune the Generator and Tuner to 90MHz and adjust Coils: L2 (FM MIX), L3 (FM RF) and L4 (FM ANT) for best sensitivity. Tune the Generator and Tuner to 104MHz and adjust Trimmer Capacitors: C60 (FM MIX), C62 (FM RF) and C63 (FM ANT) for best sensitivity. Repeat 8 and 9 until no improvement in sensitivity is noted. Tune Tuner to 90MHz with no RF Input and adjust T9 (FM DETector Primary) for zero volts between TP1 and TP2 relative (connector J6). Tune the Generator to 90MHz and adjust the RF Output to 1000uV and 100% MONO modulation at 1000Hz. Then adjust T8 (FM DETector SECondary) for lowest distortion. Reduce the Generator Output to minimum and detune the Generator so the Receiver picks up only noise, then recheck the voltage between TP1 and TP2 (connector J6). If it is not 0+/0. 2VDC, repeat steps 11 and 12. If there is interference from a station on this frequency, tune the Tuner to a nearby frequency free from interference for this measurement. Tune the Generator to 90MHz with a 1000uV output. Then switch the Generator to stereo (left only) and adjust T10 (FM IF Transformer) for the lowest distortion at the TUNER IN/OUT RCA jacks. [. . . ] Tune the Generator and Tuner to 1400kHz, then adjust Trimmer Capacitors: C106 (AM ANT) and C61 (AM RF) for best sensitivity. Note: Trimmer Capacitor C106 (AM AMT) is located on the RAA1. Repeat 8 and 9 until no improvement in sensitivity is noted. 8. Note the initial position of R70, and then adjust R70 fully counter clockwise. [. . . ]