Onkyo K-185X Cassette Tape Deck Service Manual
Model K-185X
Reference No. 3606
Safety Information
SAFETY-RELATED COMPONENT WARNING!!
Components identified by MARK A on the schematic diagram and in the parts list are critical for risk of fire and electric shock. Replace these components with Onkyo parts whose part numbers appear as shown in this manual.
Make leakage-current or resistance measurements to determine that exposed parts are acceptably insulated from the supply circuit before returning the appliance to the customer.
Specifications
| Feature | Specification |
|---|---|
| Track Format | 4-track, 2-channels |
| Erasure System | AC erase |
| Tape Speed | 4.8 cm/sec. (1-7/8 i.p.s.) |
| Wow and Flutter | 0.07% (WRMS) |
| Frequency Response | 20 – 15,000 Hz (Normal) ±3 dB (30 – 14,000 Hz ±3 dB) |
| 20 – 16,000 Hz (High) ±3 dB (30 – 15,000 Hz ±3 dB) | |
| 20 – 17,000 Hz (Metal) ±3 dB (30 – 16,000 Hz ±3 dB) | |
| S/N Ratio | Dolby NR off: 56 dB (metal position tape) |
| Noise Reduction | A noise reduction of 10 dB above 5 kHz and 5 dB at 1 kHz is possible with Dolby B NR. A noise reduction of 20 dB at 5 kHz is possible with Dolby C NR. |
| Input Jacks | Line IN: 2 |
| Input Sensitivity | 600 mV |
| Input Impedance | 50 kohms |
| Outputs | Line OUT: 2 |
| Standard Output Level | 500 mV (0 dB) |
| Optimum Load Impedance | over 50 kohms |
| Motors | DC servo motor > 1 |
| Heads | REC/PB: 1, ERASE: 1 |
| Power Consumption | 11 watts |
| Dimensions | 185(W) x 131(H) x 294(D) mm (7-5/16" x 5-1/8" x 11-9/16") |
| Weight | 2.9 kg (6.4 lbs.) |
Specifications and external appearance are subject to change without notice because of product improvements.
Block Diagram
The block diagram illustrates the internal signal flow and component interconnections for the Onkyo K-185X. Key functional blocks include:
- Input/Output: Line IN, Line OUT, and connections for the R/P Head and ERASE HEAD.
- Signal Processing: Includes Volume Control, Dolby B/C NR circuitry, MPX section, Playback Amplifier (P.B AMP), and Record Equalizer (REC EQ) Amplifier.
- Control System: A Micro Processor (Q701) manages operations, receiving input from Operation Key, Rotation Sensor (ROT.SEN.), and controlling the Mecha Drive.
- Ancillary Circuits: Bias Control, Bias Adjustment, REC MUTE, MUTE DRIVE, and LINE MUTE circuits are present.
- Power Supply: Provides necessary voltages (+12V for SIGNAL, +5V for MICRO PROCESSOR, +12V MECHA).
The diagram shows signal paths for recording and playback, highlighting the flow from input to output and the control signals managed by the micro processor.
Adjustment Procedures
Precautions
- Before adjustment, clean the recording/playback head, erase head, pinch roller, and capstan with an alcohol-moistened swab.
- Do not use a magnetized screwdriver for adjustment.
- Demagnetize the recording/playback head with a head demagnetizer.
Test Equipment/Tool Required
- Audio Oscillator
- Frequency counter
- Oscilloscope
- Attenuator
- AC voltmeter
- Non-magnetic screwdriver
- Test tapes: TCC-153 (10kHz, -15dB), MTT-111N (3kHz, -10dB), MTT-150 (Dolby level calibration, 400Hz, tone 200nWb/m)
Adjustment Table
| Item | Connection of instrument | Line output level/freq. | Test tape | Mode | Output indicator | Adjustment point | Adjustment | Remarks |
|---|---|---|---|---|---|---|---|---|
| 1. Tape speed | Frequency counter to P201 or LINE OUT terminal. | MTT-111N | PB | Frequency counter | R723 | 3010Hz | ||
| 2. Head azimuth | Oscilloscope & AC voltmeter to P201. | TCC-153 | PB | AC voltmeter | Fig.1 | Maximum level & same phase at channels L & R | Refer to Fig.2. | |
| 3. Playback level | AC voltmeter to P201. | MTT-150 | PB | AC voltmeter | R115 (L ch.), R116 (R ch.) | 300mV | The levels of recording and playback become same. | |
| 4. Bias current | Fig.3 | 1kHz, 35mV & 12.5kHz, 35mV | Normal tape | REC/PB | AC voltmeter | R415 (L ch.), R416 (R ch.) | Playback level of 1kHz and 12.5kHz becomes same. | Repeat the recording and playback until no further adjustment is necessary. |
| 5. Recording level | Fig.3 | 1kHz, 350mV | Normal tape | REC/PB | AC voltmeter | R221 (L ch.), R222 (R ch.) | The levels of recording and playback become same. | Repeat the recording and playback until no further adjustment is necessary. |
| 6. Bias frequency | Frequency counter to lead wire of erase head. | Normal tape | REC | Frequency counter | L401 | 107kHz |
Blank tapes:
- Normal: UD-I C-90 (PLAY torque: 30~70g/cm)
- High: UD-II C-90 (FF/REW torque: 80~180g/cm)
- Metal: XS C-60 (Back tension: 2~6g/cm)
Head azimuth adjustment: Refer to Fig. 1 for head azimuth screw orientation (REV/FWD).
Circuit Board Views and Parts Lists
Detailed views and component lists are provided for various circuit boards and mechanical assemblies.
Chassis-Exploded View Parts List
| Ref. No. | Part No. | Description | Ref. No. | Part No. | Description |
|---|---|---|---|---|---|
| A1 | 27110979B | Front bracket | F901A | 252075 | ▲ 2.5A-SE-EAK <P/T> |
| A2 | 27262519 | Plate T-1 | P101A | 2009990315 | NSAS-14P0449, Socket |
| A5 | 28400282 | Damper | P101B | 260208 | Wire tie |
| A6 | 27180477A | Spring | P901A | 253193HIT | ▲ AS-CEE, Power supply cord <P/T> |
| A9 | 27130748A | Bracket F | T901 | 2301104 | ▲ NPT-1239P, Power transformer <P/T> |
| A12 | 27301792A | Cassette frame | 2301153 | ▲ NPT-1239D, Power transformer <D> | |
| A13 | 27180272A | Spring | U1 | 1N277547-2B | NAAR-5447-2B, Main circuit PC board ass'y <P/T> |
| A15 | 28325129 | Knob, Eject | 1N277547-2A | NAAR-5447-2A, Main circuit PC board ass'y <D> | |
| A17 | 27100299 | Chassis | U2 | 1N277548-2A | NAAF-5448-2A, Dolby circuit PC board ass'y <D> |
| A20 | 27122514 | Rear panel <P/T> | 1N277548-2B | NAAF-5448-2B, Dolby circuit PC board ass'y <P/T> | |
| A20 | 27122513 | Rear panel <D> | U3 | 1N277549-2A | NASW-5449-2A, Switch PC board ass'y <D> |
| A21 | 27300750 | Bushing, cord | 1N277549-2B | NASW-5449-2B, Switch PC board ass'y <P/T> | |
| A23 | 830440089 | 4TTC+8C(BC), Self-tapping screw | U4 | 1N277550-2A | NAPS-5450-2A, Power supply PC board ass'y <D> |
| A24 | 838130088 | 3TTB+8B, Self-taping screw | 1N277550-2B | NAPS-5450-2B, Power supply PC board ass'y <P/T> | |
| A301 | 28184592A | Top cover | Z1 | 244246 | NDM-196, Deck mechanism ass'y |
| A303 | 838230088 | 3TTB+8B(NI), Nickel screw | |||
| A501 | 27212042 | Front panel | |||
| A502 | 28198817 | Facet, Power | |||
| A503 | 28198818 | Facet, Dolby | |||
| A504 | 28198819 | Facet, Play | |||
| A506 | 28135247Y | Badge | |||
| A508 | 27301868A-1 | Cassette lid | |||
| A509 | 27301870 | Cassette lid, base | |||
| A510 | 28191716A | Clear plate | |||
| A516 | 27175252-1B | Leg | |||
| A518 | 838130088 | 3TTB+8B, Self-taping screw |
<P>: European model only, <T>: Asian model only, <D>: 120V model only
NOTE: THE COMPONENTS IDENTIFIED BY MARK A ARE CRITICAL FOR RISK OF FIRE AND ELECTRIC SHOCK. REPLACE ONLY WITH PART NUMBER SPECIFIED.
Tape Mechanism-Exploded View Parts List
| Ref. No. | Part No. | Description | Ref. No. | Part No. | Description |
|---|---|---|---|---|---|
| 2 | 24611607 | Chassis | Z3 | 24611593A | Retainer |
| 3 | 24611609 | Head plate | Z4 | 24605798 | Spring |
| 4 | 24601282 | Main motor | Z5 | 8930301S | ES-3S, Circlip |
| 5 | 24606531 | Control PC board | Z6 | 833326047 | 2.6TTP+4S, Self-tapping screw |
| 6 | F522-037 | Clutch | A | Molikote X5, Grease | |
| 11 | FD52Y | Cam gear | B | Bond | |
| 12 | F765-277 | Solenoid coil | |||
| 25 | 24602551 | Main belt | |||
| 29 | F522-031 | Flywheel | |||
| 31 | 24602595 | Pinch roller | |||
| 32 | 24602594 | Pinch roller | |||
| 42 | 24602596 | F/R belt | |||
| Z2 | 24603404A | Lever, Eject |
Main Circuit PC Board (NAAR-5447-2A/2B) Components
| Circuit No. | Part No. | Description | Circuit No. | Part No. | Description |
|---|---|---|---|---|---|
| ICs | |||||
| Q101 | 222905 | MPC1228HA | C405 | 354744709 | 47 µF,16V, Elect. |
| Q102 | 22240147 | MPC1330HA | C406 | 370138224 | 8200pF±5%,100V, Plastic |
| Q701 | 22240887 | TMP87CH46N-4256 | C408 | 354741019 | 100 µF,16V, Elect. |
| Transistors | |||||
| Q103,Q104 | 221299 / 2213600 | DTC114TS or RN1211 | C409,C410 | 370131514 | 150pF±5%,100V, Plastic |
| Q205,Q206 | 2213090 / 2213590 | DTA114YS or RN2207 | C411,C412 | 370131014 | 100pF±5%,100V, Plastic |
| Q207,Q208 | 2211705 / 2211706 | 2SD655-E or 2SD655-F | C413-C416 | 371122734 | 0.027 μ F±5%,50V, Mylar |
| Q401 | 2211504 | 2SA950-Y | C417,C418 | 371121034 | 0.01 μ F±5%,50V,Mylar |
| Q402,Q405 | 221281 / 2213570 | DTC114YS or RN1207 | C421,C422 | 354741009 | 10 µF,16V, Elect. |
| Q403,Q404 | 2201883 | 2SC1213-C | C703,C708 | 354741009 | 10 µF,16V, Elect. |
| Q705,Q707 | 221281 / 2213570 | DTC114YS or RN1207 | C707 | 354780109 | 1 µF,50V, Elect. |
| Q706,Q708 | 2212853 / 2212855 | 2SB1068-K or 2SB1068-U | C709 | 354780479 | 4.7 µF,50V, Elect. |
| Q709 | 2213354 / 2213355 | 2SA933S-R or 2SA933S-S | C710,C905 | 354741009 | 10 µF, 16V, Elect. |
| Q901,Q904 | 2202724 / 2202725 | 2SB1569A-D or 2SB1569A-E | C904 | 393354727 | 4700 μF,25V,Elect. |
| Q902,Q905 | 2213284 / 2213285 | 2SC1740S-R or 2SC1740S-S | C906,C922 | 393342217 | 220 μF,16V,Elect. |
| Q907 | 2202705 / 2202706 | 2SD2394-E or 2SD2394-F | C907,C923 | 393341027 | 1000 μF,16V,Elect. |
| Diodes | |||||
| D701,D703 | 223163, | 1SS133, | C909 | 393324717 | 470 μ F,6.3V, Elect. |
| D704,D905 | 223205 / 223222 | 1SS270A or WG713A | Resistors | ||
| D906 | 22380035 / 22380260 | GP104003E or RL1N4003 | R115,R116 | 5210265 | N06HR50KBC,Trimming |
| D907,D909 | 224470562 | MTZJ5.6B, Zener | R117 | 443521214 | 120Ω±5%,1/2W,Metal oxide |
| D908,D910 | 224471203 | MTZJ12C, Zener | R403,R404 | 453530824 | 8.2Ω±5%,1/2W,Metal |
| Oscillator | |||||
| X701 | 3010190 | CST8.00MTW, Ceramic | R415,R416 | 5210262 | N06HR10KBC,Trimming |
| Coils | |||||
| L401 | 231223 | NLO-2064 | R723 | 5210258 | N06HR1KBC,Trimming |
| L403,L404 | 231218 | NCH-4453 | R911,R912 | 453534794 | 0.47 Ω±5%,1/2W,Metal |
| Capacitors | |||||
| C101,C102 | 374726814 | 680pF±5%,50V, Plastic | Terminals | ||
| C103,C104 | 393380227 | 2.2 µF,50V, Elect. | P701 | 25045330 | NPJ-2PDBL184, IN/OUT |
| C105,C106 | 393341017 | 100 µF,16V,Elect. | P202 | 25045338 | NPJ-4PDBL189,RI |
| C107,C108 | 374728224 | 8200pF±5%,50V, Plastic | Sockets | ||
| C109,C110 | 393341007 | 10 µF,16V, Elect. | JL704B | 25051129 | NSCT-13P916 |
| C111,C112 | 374721834 | 0.18 μ F±5%,50V, Plastic | JL906A | 25050267 | NSCT-3P95 |
| C113 | 393341027 | 1000 μF,16V,Elect. | Plugs | ||
| C401,C910 | 393322217 | 220 μF,6.3V, Elect. | JL705A | 25055633 | NPLG-12P595 |
| C402 | 371121034 | 0.01 μ F±5%,50V, Mylar | P101 | 25055136 | NPLG-6P120 |
| C403,C404 | 371123324 | 3300pF±5%,50V,Mylar | P102B | 25055709 | NPLG-13P665 |
| P103B | 25055772 | NPLG-10P728 | |||
| P201 | 25055038 | NPLG-2P29 | |||
| P401 | 25055132 | NPLG-2P116 | |||
| Radiators | |||||
| Q901A,Q904A | 27160211 | RAD-68 | |||
| Screws | |||||
| Q901B,Q904B | 838430107 | 3TTB+10S(BC) | |||
Dolby Circuit PC Board (NAAF-5448-2A/2B) Components
| Circuit No. | Part No. | Description | Circuit No. | Part No. | Description |
|---|---|---|---|---|---|
| ICs | |||||
| Q201 | 22240544 | HA12155NT | C901 | 374721044 | 0.1 μ F±5%,50V, Plastic |
| Transistors | |||||
| Q203,Q204 | 221299 / 2213600 | DTC114TS or RN1211 | Fuse | ||
| Diodes | |||||
| D201,D202 | 223163, 223205 / 223222 | 1SS133, 1SS270A or WG713A | F901A | 252075 | ▲ 2.5A-SE-EAK <P/T> |
| Coils | |||||
| L201,L202 | 233436 | NMC-6081 | F901 | 25050065 | Fuse holder |
| L203,L204 | 231085 | NCH-2133 | P901 | 25055676 | Plug |
| Capacitors | |||||
| C201-C204 | 393380227 | 2.2 µF,50V, Elect. | JL906B | 25051107 | NSCT-3P894 |
| C205-C207 | 393380107 | 1 µF,50V, Elect. | P902 | 25050684 | AC outlet |
| C209-C214 | 374722224 | 2200pF±5%,50V, Plastic | P903 | 25050410A | NSCT-2P235 <P/T> |
| C215-C218 | 374721044 | 0.1 μ F±5%,50V, Plastic | |||
| C219,C220 | 393341007 | 10 µF,16V, Elect. | |||
| C221,C222 | 393380107 | 1 µF,50V, Elect. | |||
| C223,C224 | 374721044 | 0.1 μ F±5%,50V, Plastic | |||
| C225,C226 | 354782299 | 0.22 μ F,50V, Elect. | |||
| C227,C228 | 393380227 | 2.2 μ F,50V, Elect. | |||
| C229,C230 | 393341007 | 10 µF,16V, Elect. | |||
| C233,C234 | 393341007 | 10 µF,16V, Elect. | |||
| C238 | 391944717 | 470 μF,16V, Elect. | |||
| Resistors | |||||
| R221,R222 | 5210263 | N06HR20KBC,Trimming | |||
| Sockets | |||||
| P102A | 25051238 | NSCT-13P1028 | |||
| P103A | 25051415 | NSCT-10P1202 | |||
<P>: European model only, <T>: Asian model only, <D>: 120V model only
NOTE: THE COMPONENTS IDENTIFIED BY MARK A ARE CRITICAL FOR RISK OF FIRE AND ELECTRIC SHOCK. REPLACE ONLY WITH PART NUMBER SPECIFIED.
Power Supply PC Board (NAPS-5450-2A/2B) Components
| Circuit No. | Part No. | Description | Circuit No. | Part No. | Description |
|---|---|---|---|---|---|
| Capacitor | |||||
| C901 | 374721044 | 0.1 μ F±5%,50V, Plastic | |||
| Fuse | |||||
| F901A | 252075 | ▲ 2.5A-SE-EAK <P/T> | |||
| Fuse holder | |||||
| F901 | 25050065 | YSH403T <P/T> | |||
| Plug | |||||
| P901 | 25055676 | NPLG-2P632 | |||
| Socket | |||||
| JL906B | 25051107 | NSCT-3P894 | |||
| AC outlet | |||||
| P902 | 25050684 | NSCT-2P488 <D> | |||
| P903 | 25050410A | NSCT-2P235 <P/T> | |||
<P>: European model only, <T>: Asian model only, <D>: 120V model only
Schematic Diagrams
The schematic diagrams provide a detailed electrical layout of the Onkyo K-185X cassette tape deck, illustrating the interconnections of all components. They are crucial for understanding circuit operation and troubleshooting.
Key sections covered in the schematics include:
- Audio Path: Detailed wiring for the R/P head, playback amplifier (P.B AMP), record equalizer amplifier (REC EQ AMP), and line output stages. This includes signal processing for recording and playback.
- Dolby NR Circuitry: Implementation of Dolby B/C noise reduction systems to minimize tape hiss.
- Control Systems: Connections for the main Micro Processor (Q701), which manages tape transport, playback modes, and user interface functions. It interfaces with operation keys, indicators, and the mecha drive.
- Power Supply: Distribution of necessary voltages to various circuits, including +12V for signal processing and +5V for the micro processor.
- Component Identification: Schematics use reference designators (e.g., Q101, R115, C405) that correspond to the parts lists. Components marked with 'A' are identified as critical for safety and require specific replacement parts.
The diagrams also show test points and adjustment locations, such as R723 for tape speed calibration, R115/R116 for playback level adjustment, and R415/R416 for bias current setting. Figures 2 and 3 illustrate test setups and phase relationship checks.
Associated Diagrams:
- Printed Circuit Board Views: Bottom and top side views show component placement and PCB routing, aiding in component identification and repair.
- Exploded Views: Detailed illustrations of the chassis and tape mechanism assemblies, along with corresponding parts lists, facilitate component identification and replacement for mechanical repairs.
- Adjustment Point Diagrams: Visual guides pinpoint specific components (e.g., potentiometers, resistors) that require adjustment during servicing.
- Test Setup Diagrams: Illustrations demonstrate the correct connection of test equipment (oscilloscope, voltmeter, oscillator) for calibration, measurement, and troubleshooting procedures.
