Technics SL-1800MK2 Service Manual

Specifications

Specifications are subject to change without notice. Weight and dimensions shown are approximate.

Notes:

• The model SL-1800MK2 (M) is available in U.S.A. only.
• The model SL-1800MK2 (MC) is available in Canada only.

Manufacturers:

Technics
Panasonic Company
Division of Matsushita Electric Corporation of America
One Panasonic Way, Secaucus, New Jersey 07094

Panasonic Hawaii, Inc.
320 Waiakamilo Road, Honolulu, Hawaii 96817

Matsushita Electric of Canada Ltd.
5770 Ambler Drive, Mississauga, Ontario L4W 2T3

Disassembly Procedure

This section outlines the steps for disassembling the Technics SL-1800MK2 turntable.

How to Remove Main Base Assy' and Bottom Base Assy'

1. Clamp the tone arm to the arm rest.
2. Remove head shell and turntable platter.
3. Close dust cover.
4. Turn unit upside down, taking special care not to damage or scratch the dust cover.
5. Remove 6 screws (marked 'A' in diagrams) of the audio insulator and 2 screws of the phono cord clamper, as shown in Fig. 1.
6. Holding the player firmly with both hands, to prevent separation of the upper section (bottom base ass'y) from the lower section (main base ass'y), turn it carefully upwards.
7. Remove dust cover.
8. Remove 5 screws of the panel cover, as shown in Fig. 2.
9. Remove 2 connectors and 2 read wires from the power transformer, as shown in Fig. 3.
10. To remove the main base ass'y from the bottom base ass'y, turn the cueing lever upward and move the tone arm towards the center of the spindle. The main base ass'y can be lifted up easily. (See Figs. 4, 5 and 6.)

How to Remove Drive Circuit Board

(Refer to steps 1-10.)

1. Remove 3 screws of the drive circuit board and 3 screws of the stater frame cover, as shown in Fig. 5.

How to Remove Stater Frame Coil and F-G Detector Coil

(Refer to steps 1-11.)

1. Disconnect 18 soldered parts of the stater coil and 4 soldered parts of the F-G detector coil, as shown in Fig. 7.
2. Remove 3 screws of the stater frame ass'y, as shown in Fig. 7.

How to Remove Control Circuit Board Assy'

(Refer to steps 1-10.)

1. Remove 7 screws of the control circuit board ass'y, as shown in Fig. 6.

How to Remove Stylus-Illuminator Lamp

(Refer to steps 1-10 and 14.)

1. Remove 2 screws of the stylus-illuminator lamp ass'y, as shown in Fig. 6.
2. Remove 1 screw (marked '✓') as shown in Fig. 8.

How to Remove Tone Arm and Arm Base Assy'

(Refer to steps 1-10.)

1. Remove 4 screws (marked 'A' in diagrams) as shown in Fig. 5.
2. Remove 2 screws of the phono cord p.c.b., as shown in Fig. 9.
3. Remove 2 screws (marked 'B' in diagrams) as shown in Fig. 9.
4. Remove 2 screws (marked 'C' in diagrams) of the silicon oil dumper, as shown in Fig. 9.
5. Remove 3 screws (marked 'D' in diagrams) as shown in Fig. 9.
6. Remove 2 screws (marked 'E' in diagrams) of the tone arm, as shown in Fig. 10.

Diagram References:

• Fig. 1: Illustrates screw locations for audio insulator and phono cord clamper.
• Fig. 2: Shows screw locations for the panel cover.
• Fig. 3: Depicts wire connections to the power transformer.
• Fig. 4, 5, 6: Show the main base ass'y and bottom base ass'y for removal.
• Fig. 7: Details the stater frame ass'y and F-G detector coil removal.
• Fig. 8: Illustrates the stylus-illuminator lamp removal.
• Fig. 9: Shows screw locations for tone arm and arm base components.
• Fig. 10: Illustrates screw locations for tone arm removal.

Arm Base Assembling Procedure

This section details the procedure for assembling the arm base.

1. Attach the control ring to the arm base seat. The control ring should be rotated counterclockwise.
2. Completely tighten the control ring, then loosen it 1.5-2.5 turns to set the scale to "3". (See Fig. 11)
3. Hold the arm base and set the red line mark on the arm base to the scale near "2", then turn the arm base clockwise. (See Fig. 12)
4. Adjust the arm base so that the red line mark on the arm base is set to the scale "3" of the control ring. Next, secure the positioning base plate with two setscrews. (See Fig. 13)
5. Rotate the control ring and ensure that the arm base shifts within the range of 0-6mm. (See Figs. 14 and 15) If it does not shift within the specified range, the arm base position is deflected. In that case, disassemble the parts and check as specified in step 3.

Note: Take care not to allow deflection of the predetermined positions of the control ring and arm base seat.

Adjustment of Canceller Spring Position

This procedure is for setting the canceller spring position when the arm body or PU base plate is replaced.

1. Clamp the arm on the rest.
2. Set the canceller knob to "0.5".
3. Remove the PU base plate, adjust the gear so that the canceller spring is in the position shown in Fig. 16.
4. Mount the PU base plate onto the arm base and check the spring position.

Note: Ensure the canceller spring is in contact with the arm shaft.

How to Install the Drive Circuit Board Assembly

This section describes the installation of the drive circuit board assembly.

1. The circuit board assembly can be detached by removing the 4 setscrews shown in Fig. 1. When installing it onto the bottom base assembly after adjustment and repair, follow the procedure mentioned below.
2. Temporarily tighten the 4 setscrews (marked '1' in diagrams). (Refer to Fig. 1.)
3. Adjust so that the center spindle is aligned to the center of the turntable, provided with equal clearances (marked '2' in diagrams) as in Fig. 17.
4. Completely tighten the 4 setscrews, taking care not to allow deflection of the center spindle.

Parts Identifications

This section identifies key components of the turntable.

Key Components:

• Hinge
• Turntable base
• Turntable mat
• Center spindle
• Turntable platter
• Strobe dots
• Strobe-illuminator/LED
• Start-stop button
• Speed select buttons
• Pitch indicator
• Tone arm
• Arm-height adjustment ring
• Balance weight
• Stylus-pressure ring
• Anti-skating control knob
• Arm rest
• Cueing lever
• Arm clamp
• Tonearm
• Locking nut
• Headshell
• Stylus illuminator switch
• Power switch (ON/OFF)
• Stylus illuminator
• Pitch control knob

Diagrams (Fig. 17, Fig. 18) visually label these parts.

Features

The Technics SL-1800MK2 offers several advanced features:

Total Quartz Locked Continuous Pitch Adjustment (±6%)

Quartz-phase-locked control ensures high rotational accuracy. The "quartz synthesizer" system maintains accuracy even when pitch is altered. Pitch is variable analogically up to ±6% via a front panel knob, indicated by thirteen LEDs. The system remains under quartz control for precise speed.

Double Isolated Suspension System with TNRC Inner Base

To combat acoustic feedback, a double isolated suspension system is employed. The outer base is diecast aluminum, supported by isolators. The inner base, made from Technics Non-Resonant Compound (TNRC) material, supports the platter, motor, and tonearm base, and is also supported by isolators. This dual suspension minimizes feedback issues. The platter itself is double-damped with a specially fabricated rubber mat on both sides.

All Front-Panel Controls

Controls, including the cueing control and LED display, are conveniently located in-line on the front panel. Precision-designed buttons require moderate pressure for activation, providing a sense of positive control and preventing accidental operation.

High-Sensitivity, Low Mass Gimbal Suspension Tonearm

The tonearm features a genuine "gimbal" design with a single rotational center point. Bearings are precise (±0.5 microns tolerance). This, combined with close-proximity bearings, results in an effective friction of 7 mg for both horizontal and vertical movement. The low, 12-gram effective mass (including headshell) makes it compatible with a wide range of cartridge compliances.

Quartz Oscillator-Controlled Strobe Illuminator with Four Indication Lines

A quartz-controlled LED strobe illuminates four lines on the platter edge, corresponding to speed change percentages (+6%, +3.3%, 0%, -3%). When these lines appear stationary, the platter is rotating at the indicated speed.

Stylus Illuminator for Low-Light Conditions

A pop-up stylus illuminator aids in low-light conditions or when the turntable is in a rack. It can be activated by a button and casts a light beam across the record area, allowing precise cueing. It retracts back into the base when not needed.

Other Fine Features

• High torque for fast starts.
• Excellent load characteristics for steady speed.
• Helicoid tonearm height adjustment.
• Electronic braking system for quick platter stops.
• Prism strobe illuminator governed by a quartz oscillator for stable operation.
• Soft-touch switches for positive control and minimized accidental operation.
• Technics integral rotor/platter structure with full-cycle detection FG.

Figure 19 illustrates the Double Isolated Suspension system.

Wiring Connection

The wiring diagram (Fig. 7) shows the connections between the power transformer, power supply circuit board, drive circuit board, stater frame ass'y, stylus-illuminator lamp, and control circuit board. Key connections include:

• Power Transformer to Power Supply Circuit Board (AC lines, etc.)
• Power Supply Circuit Board to Drive Circuit Board (BLU, BLU)
• Drive Circuit Board to Stater Frame Ass'y (RED, YEL, ORG, BLU, BLK, YEL, ORG, RED, BRN)
• Drive Circuit Board to Stylus-Illuminator Lamp (RED, YEL, ORG, BLU, BLK, YEL, ORG, RED, BRN)
• Drive Circuit Board to Control Circuit Board (various connections via connectors J1, J2, J3).

Adjustments

Pitch Control (Fine Adjustment of Speed)

When the power switch is turned ON, the LED lamp indicates the unit is active. With the pitch control knob at the "0" position, regular speed (33-1/3 or 45 rpm) is maintained, indicated by a green LED. The pitch control allows speed variation from 0 to ±6%. Proper speed variation is monitored via a red LED lamp and a scale on the indicator. Multiple LEDs lighting up indicate a range of speed variation (e.g., 2-3%). The strobe dots on the turntable edge appearing stationary indicate precise individual pitch settings. The strobe illumination uses a quartz-synchronized LED, not affected by fluorescent lamps.

Note: The LED illumination is not synchronized with fluorescent lamps.

Adjustment of Arm-Lift Height

The arm-lift height (distance between stylus tip and record surface when cueing lever is raised) is factory-set to approximately 8-13 mm. To adjust, turn the adjustment screw clockwise (decreases distance) or counterclockwise (increases distance) while depressing the arm lift. Ensure the hexagonal head retracts correctly into the arm lift after adjustment.

Adjustment of the Tonearm Height

The tonearm height can be adjusted up to 6 mm, with a scale on the adjust ring in 0.5 mm increments. Use the adjust ring scale and the provided table to set the correct arm height. For example, a cartridge height of 17.5 mm requires positioning the adjust ring between scale marks 2 and 3.

Caution: Lock the tonearm using the arm lock knob after height adjustment.

Lubrication

Apply 2 or 3 drops of oil once every 2000 hours of operation. This interval is significantly longer than for conventional motors (200-500 hours). Use original oil (Part number is SFWO 010).

Adjustments (Electrical)

These adjustments are made after replacing parts like ICs, transistors, or diodes. The set should be ON, pitch control at center position, speed selector at 33-1/3 r.p.m. Instruments required are an oscilloscope and a frequency counter.

Adjustment of Pitch Control (±0% PITCH)

• Connection Points: Frequency counter to TP27 (+), GROUND to TP27 (-).
• Adjustment Point: VR301.
• Adjustment Method: Adjust VR301 for 262.08 kHz ±0.05 kHz frequency.

Adjustment of Pitch Control Frequency (GAIN)

• Connection Points: Frequency counter to TP27 (+), GROUND to TP27 (-).
• Adjustment Point: VR425.
• Adjustment Method: Adjust pitch control switch for 269.94 kHz frequency. Adjust VR425 so that the LED (Pitch indicator plus 3%) lights up.

Braking (BRAKE) Adjustment

• Adjustment Point: VR201.
• Adjustment Method: Adjust VR201 for complete stop within 120°-270° after stop signal initiation. The turntable becomes free a few seconds after stop.

Reference Voltage and Waveform at Each IC Pin and Test Point

Detailed tables provide reference voltages and waveforms for various ICs (IC101 AN6675, IC201 AN6680, IC301 AN6682, IC302 SVITC4011BP, Q202 2SD637) at different operational states (Start/Stop). These are crucial for diagnosing circuit issues.

Schematic Diagram

The schematic diagrams provide a detailed circuit layout for the Drive Circuit Board and Control Circuit Board. They illustrate the interconnections of ICs, transistors, diodes, resistors, capacitors, switches, and connectors. Key sections include Braking Adjustment, Pitch Control Adjustment, and connections to the power transformer and other circuit boards. The diagrams also include terminal guides for transistors and ICs, listing pin functions and typical voltage values.

Troubleshooting

A troubleshooting flowchart guides technicians through diagnosing common issues, categorized by symptom:

• (A) Power switch doesn't operate: Checks power circuitry (F1, S601, T1) and reference voltage circuitry (D1, IC1, D2, Q1-Q3).
• (B) It doesn't rotate: Checks drive circuit board, control circuit board, and reference voltage circuitry.
• (C) Runaway operation: Checks reference voltage circuitry and control circuit board.
• (D) Turntable rotates abnormally: Checks pitch control circuitry (IC201, X201), speed changeover circuitry (IC201), and drive circuitry (IC101).
• (E) Speed changeover is defective: Checks speed select circuitry (IC201) and control circuitry (IC201, X201).
• (F) Strobe not illuminating: Checks voltage at TP28 and TP29, drive circuitry (IC101), and FG circuitry (Q203, FG coil).
• (G) Pitch control malfunction: Checks voltage on Q201, pitch control circuitry, and control circuitry (IC428, IC429).
• (H) Pitch control-LED not illuminating: Checks voltage at IC429 and control circuitry (IC428, IC429).

Each step involves checking specific components or voltages using an oscilloscope and frequency counter.

Printed Circuit Board Layouts

Diagrams of the Printed Circuit Boards (Drive Circuit Board, Control Circuit Board, Power Supply PCB, Stylus-Illuminator Switch PCB) are provided, showing the physical placement of components and their interconnections. These are essential for component-level repair and identification.

Replacement Parts List (Electrical)

A comprehensive list of replacement parts is provided, categorized by component type (Integrated Circuits, Transistors, Diodes, Crystal, Variable Resistors, Switches, Lamp, Transformer, Fuse, Resistors). Each entry includes a reference number, part number, and description. Special notes indicate parts critical for safety (marked with 'A') that must be replaced with manufacturer-specified parts.

Block Diagram

The block diagram illustrates the overall system architecture of the SL-1800MK2. It shows how various functional blocks, such as the Position detection coil, IC101 (AN6675), IC201 (AN6680), IC301 (AN6682), IC425-IC429, and power circuits, are interconnected. It highlights the signal flow for speed control, pitch adjustment, braking, and strobe illumination.

Exploded Views

Multiple exploded views visually break down the turntable into its constituent parts, showing their relative positions and how they assemble. These diagrams are crucial for mechanical disassembly, reassembly, and identifying specific components for replacement.

Important Safety Notice

The manual emphasizes that shaded areas in the schematic diagrams incorporate special features important for safety. When servicing, only manufacturer-specified parts must be used for critical components in these shaded areas.