Jvc MXSK 1 Service Manual

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1-2 (No.MB207) SPECIFICATION Design & specifications are subject to change without notice.Amplifier section Output Power MAIN SPEAKERS 64 W per channel min. RMS both channels driven into 6 -„¦ at 1 kHz with no more than 0.9% total harmonic distortion. Audio input sensitivity/Impedance (Measured at 1 kHz with tape record- ing signal 300 mV)AUX 400 mV/50 k-„¦ MIC 3 mV/10 k-„¦ Tuner FM tuning range 87.50 MHz to 108.00 MHz AM tuning range At 9 kHz intervals 531 kHz to 1 710 kHz At 10 kHz intervals 530 kHz to 1 710 kHz CD player CD capacity 3 CDs Dynamic range 85 dB Signal-to-noise ratio 90 dB Wow and flutter Immeasurable Cassette deck Frequency response Normal (type I) 50 Hz to 14 000 Hz Wow and flutter 0.15% (WRMS) General Power requirement AC 110 V / AC 127 V / AC 220 V / AC 230 V to AC 240 V (adjustable with the voltage selector) Power consumption 50 Hz / 60 Hz 100 W (at operation) 20 W (on standby) Dimensions (approx.) 270 mm x 306 mm x 433.5 mm (W/H/D) Mass (approx.) 9.2 kg Speaker Specifications Type 3-Way 3 Speaker Bass-Reflex (Magnetically-Shielded Type) Speakers Main woofer 15cm cone x 1 Mid Range 5.0cm cone x 1 Tweeter 2.0cm dome x 1 Power Handling Capacity 80 W Impedance 6 -„¦ Frequency Range 42 Hz to 30 000Hz Sound Pressure Level 84 dB/W.m Dimensions (W x H xD) 215mm x 306 mm x 243 mm Mass 3.4 kg

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(No.MB207)1-3 SECTION 1 PRECAUTION 1.1 Safety Precautions (1) This design of this product contains special hardware and many circuits and components specially for safety purpos- es. For continued protection, no changes should be made to the original design unless authorized in writing by the manufacturer. Replacement parts must be identical to those used in the original circuits. Services should be per- formed by qualified personnel only. (2) Alterations of the design or circuitry of the product should not be made. Any design alterations of the product should not be made. Any design alterations or additions will void the manufacturers warranty and will further relieve the manufacture of responsibility for personal injury or property damage resulting therefrom. (3) Many electrical and mechanical parts in the products have special safety-related characteristics. These characteris- tics are often not evident from visual inspection nor can the protection afforded by them necessarily be obtained by us- ing replacement components rated for higher voltage, watt- age, etc. Replacement parts which have these special safety characteristics are identified in the Parts List of Ser- vice Manual. Electrical components having such features are identified by shading on the schematics and by ( ) on the Parts List in the Service Manual. The use of a substitute replacement which does not have the same safety charac- teristics as the recommended replacement parts shown in the Parts List of Service Manual may create shock, fire, or other hazards. (4) The leads in the products are routed and dressed with ties, clamps, tubings, barriers and the like to be separated from live parts, high temperature parts, moving parts and/or sharp edges for the prevention of electric shock and fire hazard. When service is required, the original lead routing and dress should be observed, and it should be confirmed that they have been returned to normal, after reassem- bling. (5) Leakage shock hazard testing After reassembling the product, always perform an isola- tion check on the exposed metal parts of the product (an- tenna terminals, knobs, metal cabinet, screw heads, headphone jack, control shafts, etc.) to be sure the product is safe to operate without danger of electrical shock.Do not use a line isolation transformer during this check. - Plug the AC line cord directly into the AC outlet. Using a "Leakage Current Tester", measure the leakage current from each exposed metal parts of the cabinet, particular- ly any exposed metal part having a return path to the chassis, to a known good earth ground. Any leakage cur- rent must not exceed 0.5mA AC (r.m.s.). - Alternate check method Plug the AC line cord directly into the AC outlet. Use an AC voltmeter having, 1,000-„¦ per volt or more sensitivity in the following manner. Connect a 1,500-„¦ 10W resistor paralleled by a 0.15µF AC-type capacitor between an ex- posed metal part and a known good earth ground. Measure the AC voltage across the resistor with the ACvoltmeter. Move the resistor connection to each exposed metal part, particularly any exposed metal part having a return path to the chassis, and measure the AC voltage across the resistor. Now, reverse the plug in the AC outlet and repeat each measurement. Voltage measured any must not exceed 0.75 V AC (r.m.s.). This corresponds to 0.5 mA AC (r.m.s.). 1.2 Warning (1) This equipment has been designed and manufactured to meet international safety standards. (2) It is the legal responsibility of the repairer to ensure that these safety standards are maintained. (3) Repairs must be made in accordance with the relevant safety standards. (4) It is essential that safety critical components are replaced by approved parts. (5) If mains voltage selector is provided, check setting for local voltage. 1.3 Caution Burrs formed during molding may be left over on some parts of the chassis. Therefore, pay attention to such burrs in the case of pre- forming repair of this system. 1.4 Critical parts for safety In regard with component parts appearing on the silk-screen printed side (parts side) of the PWB diagrams, the parts that are printed over with black such as the resistor ( ), diode ( ) and ICP ( ) or identified by the " " mark nearby are critical for safety. When replacing them, be sure to use the parts of the same type and rating as specified by the manufacturer. (This regulation dose not Except the J and C version) Good earth groundPlace this probe on each exposed metal part. AC VOLTMETER (Having 1000 ohms/volts, or more sensitivity) 1500 10W 0.15 F AC TYPE

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(No.MB207)1-13 3.1.9 Removing the rear panel (See Fig.21~25) - Prior to performing the following procedure, remove the metal cover and the CD changer unit. (1) Disconnect the wire from the connector CN1 on the tuner pack assembly on the right side of the body. (2) Disconnect the wire from the connector CN411 , CN711 on the AUX surround board. (3) Remove the screw K attaching the rear cover on the back of the body. (4) Remove the two screws L attaching the speaker board, and the two screws M attaching the power transformer board on the back of the body. (5) Remove the four screws N attaching the heat sink on the back of the body. (6) Remove the screw P attaching the rear cover on the back of the body. (7) Release the two joints f and g on the bottom of the rear panel using the screw driver, then detach the rear panel backward. Reference: The rear panel comes off with the tuner pack assembly and the AUX surround board. Fig.21 Fig.22Fig.23 Fig.24 Fig.25 Tuner pack (CN1) AUX & surroud board (CN411) Rear panel K Rear panel Rear cover N N P Rear panel Heat sink M L f Rear panel f Rear panel

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(No.MB207)1-33 4.6 Electrical performance 4.7 Reference values for electrical function confirmation items Adjustment of recording bias current (Reference value) Adjustment of recording and playback frequency characteristicsReference frequency :1kHz and 10kHz (REF:-20dB) Test tape :TYP AC-225 Measurement input terminal :OSC IN1.With the recording and playback mechanism,load the test tape(AC-225 to TYP ),and set the mechanism to the recording and pausing condition in advance. 2.While repetitively inputting the reference frequency signal of 1kHz and 10kHz from OSC IN, record and playback the test tape. 3.While recording and playing back the test tape in TYP ,adjust VR101 for LcH and VR201 for RcH so that the output deviation between 1kHz and 10kHz becomes -1dB 2dB.Output deviation between 1kHz and 10kH :-1dB 2dB 1.With the recording and playback mechanism, load the test tapes(AC-225 to TYP ),and set the mechanism to the recording and pausing conditions in advance. 2.After connecting 100 in series to the recorder head,measure the bias current with a valve voltmeter at both of the terminals. 3.After resetting the [PAUSE] mode,start recording. At this time,adjust VR101 for LcH and VR201 for RcH so that the recording bias current values become 4.0 A (TYP ). *Mode : Forward or reverse mode *Recording mode *Test tape : AC-225 Measurement output terminal :Both recording and headphone terminalsAC-225 :4.20 ALcH :VR101 RcH :VR201 LcH :VR101 RcH :VR201 Items Measurement conditions Measurement method Standard valuesAdjusting positions Items Measurement method Recording bias frequency Eraser current (Reference value)1.While changing over to and from BIAS 1 and 2, confirm that the frequency is changed. 2.With the recording and playback mechanism. load the test tape (AC-225 to TYP ),and set the mechanism to the recording and pausing conditions in advance. 3.Confirm that the BIAS TP frequency on the P.C.board is 100kHz 6kHz. 1.With the recording and playback mechanism, load the test tapes(AC-225 to TYP ),and set the mechanism to the recording and pausing condition in advance. 2.After setting to the recording conditions,connect 1M in series to the eraser head on the recording and playback mechanism side,and measure the eraser current from both of the eraser terminal.100kHz +9kHz -7kHz TYP :75mA Measurement conditionsStandard valuesAdjusting positions *Recording and playback side forward or reverse *Test tape :TYP AC-225 *Measurement terminal BIAS TP on P.C.board *Recording and playback side forward or reverse *Recording mode *Test tape :AC-225 Measurement terminal Both of the eraser head

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(No.MB207) AV & MULTIMEDIA COMPANY AUDIO/VIDEO SYSTEMS CATEGORY 10-1,1chome,Ohwatari-machi,Maebashi-city,371-8543,Japan VICTOR COMPANY OF JAPAN, LIMITED WPC Printed in Japan