AKAI GX-4000DB (01) PDF MANUAL

In case of trouble, etc. necessitating dismantling, please dismantle in the order shown in the photographs (1 through 8 on page 5 of the PDF). Reassemble in reverse order.

1. Remove screws for the Side Board (refer to photograph 1).

2. Remove screws for the other Side Board (refer to photograph 2).

3. Remove screws for the Bottom Plate (refer to photograph 3).

4. Remove screws for the Upper Cover (refer to photograph 4).

5. Remove screws for the Back Board (refer to photograph 5).

6. Remove screws & knobs for the Head Cover, Pinch Roller Cap, and Pinch Roller (refer to photograph 6).

7. Remove screws for the Front Panel (refer to photograph 7).

8. Photograph 8 shows the internal view after front panel removal.

The controls are as follows (Refer to Fig. 1 Controls):

1. PINCH ROLLER

2. CAPSTAN

3. REEL RETAINER (Left)

4. SUPPLY REEL TABLE

5. HEAD COVER

6. TAPE GUIDE

7. INDEX COUNTER & RESET BUTTON

8. TRACK SELECTOR

9. VU METERS (Left & Right)

10. OUTPUT VOLUME

11. HEADPHONE JACK

12. RECORDING INDICATOR LAMP

13. RECORDING SAFETY BUTTON

14. AUTOMATIC STOP LEVER

15. REEL RETAINER (Right)

16. TAKE-UP REEL TABLE

17. RECORDING/PLAYBACK LEVER

18. FAST FORWARD/REWIND LEVER

19. PAUSE LEVER

20. START BUTTON

21. POWER

22. MONITOR SELECTOR SWITCH (Tape & Source)

23. S.O.S. (Sound-On-Sound) BUTTON

24. MICROPHONE JACKS (Left & Right)

25. MICROPHONE RECORDING LEVEL CONTROLS

26. LINE RECORDING LEVEL CONTROLS

27. TAPE SELECTOR SWITCH

28. EQUALIZER SWITCH

29. DIN JACK

30. LINE OUTPUT JACKS (Left & Right)

31. LINE INPUT JACKS (Left & Right)

32. DOLBY N.R. INDICATOR LAMP (for GX-4000DB model)

33. S.O.S. SWITCH/LINE RECORDING LEVEL CONTROLS (for GX-4000DB model)

34. DOLBY N.R. SWITCH (for GX-4000DB model)

To measure pinch roller pressure (Refer to Fig. 4):

1. Set the recorder in the PLAY Mode.

2. Pull the pinch roller 1-2 mm away from the capstan with the spring gauge as shown in Fig. 4.

3. Slowly release and take the spring gauge reading when the pinch roller touches the capstan and begins to rotate.

The specified pinch roller pressure is 1150-1200g. (Tape speed: 7-1/2 ips).

Reel table block adjustment (Refer to Figs. 5, 6).

Necessary points when measuring the tension: Wind the tape onto a 5″ empty reel until there is a diameter of 60 mm of tape. (See Fig. 5). Make the end of the tape into a loop and put onto the spring gauge.

A. SUPPLY REEL TABLE BLOCK ADJUSTMENT

1) RWD Tension Adjustment: A spring gauge reading of 400-500g in the RWD Mode. To adjust, increase or decrease the number of (1) washers.

2) PLAY Mode Back Tension Adjustment: A spring gauge reading of 100-120g in PLAY Mode. To adjust, increase or decrease the number of (2) washers.

3) FF Free Tension Adjustment: A spring gauge reading of 15-20g in the FF Mode. To adjust, move the position of pulley (3) backwards and forwards.

B. TAKE-UP REEL TABLE BLOCK ADJUSTMENT

1) FF Tension Adjustment: A spring gauge reading of 400-500g in the FF Mode. To adjust, increase or decrease the number of (1) washers.

2) PLAY Tension Adjustment: A spring gauge reading of 150-180g in the PLAY Mode. To adjust, increase or decrease the number of (2) washers.

3) RWD Free Tension Adjustment: A spring gauge reading of 15-20g in the RWD Mode. To adjust, move the position of pulley (3) backwards and forwards.

Adjust position of drive belt so that it comes to the center of the motor pulley by inserting a washer (or washers) between the motor prop and mechanism chassis as shown in Fig. 7 (Fig. 12 in the PDF is referenced as showing the washer placement, likely Fig. 7 is a detail).

With a minus screw driver, turn bearing to left and right and adjust so that when the flywheel is moved as indicated by the arrow mark in the figure, the gap between the steel ball and flywheel supporting plate is 0.3 mm as shown in Fig. 8. Fix at this position with nut.

Loosen screws (a) and (b) and adjust installed position of Micro Switch so that when AS Lever is lowered as a result of the Power Switch being set to SHUT-OFF position, the gap between AS Lever is about 5 mm (Refer to Fig. 9).

(Refer to Fig. 10)

1) Erase Head: Loosen screws (a) and (b) shown in Fig. 10 and adjust erase head height. Tighten screws at position at which the upper edge of the tape is 0.1 mm lower than the upper edge of the left channel head core of the erase head.

2) Recording Head: Adjust head height adjustment screws (c) and (d) shown in Fig. 10 so that the upper edge of the tape and the upper edge of left channel head core of the recording head are the same height.

3) Playback Head: Adjust head height adjustment screws (f) and (g) shown in Fig. 10 so that the upper edge of the tape and the upper edge of left channel head core of the playback head are the same height.

(Refer to Fig. 10)

1) Playback Head:

a. Connect a High Sensitivity AC Voltmeter to the left and right channel Output Terminals of the tape deck.

b. Set the Track Selector to STEREO and set the machine to 7-1/2 ips tape speed.

c. Playback an 8,000 Hz 3-3/4 ips alignment adjustment test tape.

d. Adjust adjustment screw (h) to obtain maximum High Sensitivity AC Voltmeter indication on both channels.

2) Recording Head:

a. Connect an Audio Frequency Oscillator to the line input through an Attenuator, and connect a High Sensitivity AC Voltmeter to the line output. Then load a blank test tape.

b. Set the Monitor Switch to SOURCE and supply a 16,000 Hz sine wave signal. Adjust the Attenuator or the Line Recording Level Controls to obtain a -20 dBm High Sensitivity AC Voltmeter indication.

c. Reset Monitor Switch to TAPE and set deck to recording mode.

d. Adjust adjustment screw (e) to obtain maximum High Sensitivity AC Voltmeter indication on both channels.

(Refer to Fig. 10)

1) Playback Head:

a. Connect a High Sensitivity AC Voltmeter to the left and right channel Output Terminals of the tape deck.

b. Set the Track Selector to STEREO and set the machine to 7-1/2 ips tape speed.

c. Playback an 8,000 Hz 3-3/4 ips alignment adjustment test tape.

d. Loosen screw (j). Adjust PB angle in the direction of the arrow and change the angle of the head-to-tape contact. Fix the PB head at a position where the output level is not affected by an additional tension to the supply reel (e.g. slightly touching the supply reel).

2) Recording Head:

a. Connect an Audio Frequency Oscillator to the line input through an Attenuator, and connect a High Sensitivity AC Voltmeter to the line output. Then load a blank test tape.

b. Set the Monitor Switch to SOURCE and supply a 16,000 Hz sine wave signal. Adjust the Attenuator or the Line Recording Level Controls to obtain a -20 dBm High Sensitivity AC Voltmeter indication.

c. Reset Monitor Switch to TAPE and set deck to recording mode.

d. Loosen screw (i). Adjust REC angle in the direction of the arrow and change the angle of the head-to-tape contact. Fix the REC head at a position where the output level is not affected by an additional tension to the supply reel (e.g. slightly touching the supply reel).

NOTES for Head Adjustment:

1. As head adjustment greatly affects tape deck performance, be sure that these adjustments are carried out properly.

2. Be careful not to use magnetized tools near the heads.

3. As the level of old tape varies greatly, use new tape.

4. Demagnetize heads before and after head adjustment.

Refer to Fig. 11 for Instruments Connection and Fig. 12 for Amp P.C Board LE-5801A. The adjustment steps are as follows:

Step	Adjustment Item	Test Tape Supply Signal	Mode	Adjustment Point	Result	Remarks
1	Playback Level Adjustment	700 Hz 7-1/2 ips Test Tape	PLAY	VR2 50 kΩ(L) VR5 50 kΩ(R)	0 dBm ±0.5 dBm (0.775V)	Set Monitor Switch to “TAPE”.
2	VU Meter Sensitivity Adjustment	700 Hz 7-1/2 ips Test Tape	PLAY	VR3 5 kΩ(L) VR6 5 kΩ(R)	0 VU indication
3	Frequency Response Adjustment	SCOTCH #211 tape 1,000 Hz 10,000 Hz -20 VU recording	REC/PLAY	VC1 80P(L) VC2 80P(R)	Adjust to +1 dB at 10,000 Hz in relation to 1,000 Hz	Tape Speed to 3-3/4 ips. Set EQ Switch to “3-3/4”.
4	Recording Level Adjustment	SCOTCH #211 tape 1,000 Hz 0 VU recording	REC/PLAY	REC Volume (VR8 50 kA)	0 dBm ±0.5 dBm (0.775V)	Set Monitor Switch to “TAPE”
		SCOTCH #211 tape 1,000 Hz 0 VU recording	REC/PLAY	VR1 5 kΩ(L) VR4 5 kΩ(R)	0 dBm ±0.5 dBm (0.775V)	Set Monitor Switch to “SOURCE”.
5	Distortion Factor Confirmation	1,000 Hz 0 VU recording	REC/PLAY		Less than 1.0%	(Refer to NOTE 5)
6	PB Amp Bias Filter Adjustment	100 kHz from an oscillator	REC	VL1 23 mH(L) VL2 23 mH(R)	Minimum AC Voltmeter indication	Set Monitor Switch to “TAPE”. (Refer to NOTES 6, 7)
7	REC Amp Bias Filter Adjustment	100 kHz from an oscillator	REC	VL3 23 mH(L) VL4 23 mH(R)	Minimum AC Voltmeter indication	Set Monitor Switch to “SOURCE”. (Refer to NOTES 6, 7)

NOTES:

1. Output Level Control should be at maximum.

2. Except for Step 3, set tape speed to 7-1/2 ips.

3. Set tape selector to Low Noise position.

4. (L) = Left Channel, (R) = Right Channel.

5. If it does not comply with the specifications, repeat Steps 3, 4 and re-adjust.

6. Unless the core is moved intentionally this adjustment is not necessary.

7. Adjust the oscillator’s frequency to give a frequency counter reading of 100 kHz.

Refer to Fig. 13 for Amp P.C Board LE-5701A. The adjustment steps are as follows:

Step	Adjustment Item	Test Tape Supply Signal	Mode	Adjustment Point	Result	Remarks
1	Playback Level Adjustment	700 Hz 7-1/2 ips Test Tape	PLAY	VR4 50 kB	-2.5 dBm ±0.5 dBm (580 mV)	Set Monitor Switch to “TAPE”.
2	VU Meter Sensitivity Adjustment	700 Hz 7-1/2 ips Test Tape	PLAY	VR5 1 kB	0 VU indication
3	Frequency Response Adjustment	SCOTCH #211 tape 1,000 Hz 10,000 Hz, -20 VU recording	REC/PLAY	VC1 80P(L) VC2 80P(R)	Adjust to +1 dB at 10,000 Hz in relation to 1,000 Hz	Tape Speed to 3-3/4 ips. Set EQ Switch to “3-3/4”.
4	Recording Level Adjustment	1,000 Hz 0 VU from an oscillator	STOP	REC Volume (VR2 50kA)	-2.5 dBm ±0.5 dBm (580 mV)	Set Monitor Switch to “SOURCE”.
		SCOTCH #211 tape 1,000 Hz 0 VU Recording	REC/PLAY	VR3 10 kB	-2.5 dBm ±0.5 dBm (580 mV)	Set Monitor Switch to “TAPE”.
5	Distortion Factor Confirmation	1,000 Hz 0 VU recording	REC/PLAY		Less than 1.0%
6	PB Amp Bias Filter Adjustment	100 kHz from an oscillator	REC	FL2 12A-938	Minimum AC Voltmeter indication	Set Monitor Switch to “TAPE”. (Refer to NOTES 6, 7)
7	REC Amp Bias Filter Adjustment	100 kHz from an oscillator	REC	FL1 D07-003	Minimum AC Voltmeter indication	Set Monitor Switch to “SOURCE”. (Refer to NOTES 6, 7)
8	19 kHz Filter Adjustment	19 kHz from an oscillator	STOP	FL3 D07-001	Minimum AC Voltmeter indication	DOLBY N.R. Switch to ON. (Refer to NOTE 8)

NOTES:

1. Output Level Control should be at maximum.

2. Except for Step 3, set tape speed to 7-1/2 ips.

3. Set tape selector to Low Noise position.

4. (L) = Left Channel, (R) = Right Channel.

5. If it does not comply with the specifications, repeat Steps 3, 4 and re-adjust.

6. Unless the core is moved intentionally this adjustment is not necessary.

7. Adjust the oscillator’s frequency to give a frequency counter reading of 100 kHz.

8. Adjust the oscillator’s frequency to give a frequency counter reading of 19.00 kHz.

1. This parts list is compiled by various individual blocks based on assembly process.

2. When ordering parts, please describe parts number, serial number, and model number in detail.

3. How to read List:

– The reference number corresponds with illustration or photo number of that particular parts list.

– The number like “12-115x” has “12” corresponding to the Figure Number and “115” corresponding to the individual parts index number in that figure. A small “x” indicates the inability to show that particular part in the Photo or Illustration.

– Schematic Diagram Number of individual manufactured part (not required for parts order).

4. The symbol numbers shown on the P.C. Board list can be matched with the Composite Views of Components of the Schematic Diagram or Service Manual.

5. Please utilize separate “Common List for Service Parts” for Resistor Parts orders.

6. The shape of the parts and parts name, etc. can be confirmed by comparing them with the parts shown on the Electrical Parts Table of P.C. Board.

7. Both the kind of part and installation position can be determined by the Parts Number. To determine where a parts number is listed, utilize Parts Index at end of Parts List. It is necessary first of all to find the Parts Number. This can be accomplished by using the Reference Number listed at right of parts number in the Parts Index (meaning of ref. no. outlined in Item 3 above).

8. Utilize separate “Price List for Parts” to determine unit price. The most simple method of finding parts Price is to utilize the reference number.

CAUTION:

1. When placing an order for parts, be sure to list the parts no. model no., and description. There are instances in which if any of this information is omitted, parts cannot be shipped or the wrong parts will be delivered.

2. Please be careful not to make a mistake in the parts no. If the parts no. is in error, a part different from the one ordered may be delivered.

3. Because parts number and parts unit supply in the Preliminary Service Manual (Basic Parts List) may be partially changed, please use this parts list for all future-reference.

WARNING: A triangle symbol indicates SAFETY CRITICAL COMPONENTS. FOR CONTINUED SAFETY, REPLACE SAFETY CRITICAL COMPONENTS ONLY WITH MANUFACTURER’S RECOMMENDED PARTS.

This model is equipped with an AC INLET SYSTEM. By the AC INLET SYSTEM, AC (mains) cord can be connected to and disconnected from the model because the model is provided with socket exclusively for AC (mains) cord on its main body. Please note, however, that certain models are not equipped with this system and has a built-in AC (mains) cord as before.

CLASS I: Connects to machine’s AC Inlet. Used in most of European countries, Denmark, U.K., Australia (differs according to wall socket).

CLASS II: This mark indicating double insulation will be attached to machine’s rear panel. Connects to machine’s AC Inlet. Used in most of the European countries, U.K., Australia (differs according to wall socket).

The AC INLET is shown in Picture 1, to be installed on machines. The AC (mains) cord is shown in Picture 2.

The parts list for the AC (mains) Cord Set is as follows:

Standard	Description	Type of AC Inlet	Parts No.
Class I	CEE	Cord Set CEE (3 cores)	3P	EW302993
	BEAB	Cord Set BEAB (3 cores)	3P	EW302994
	SAA	Cord Set SAA (3 cores)	3P	EW302996
	U/T	Cord Set U/T (3 cores)	3P	EW302646
Class II	CEE	Cord Set CEE (2 cores)	2P	EW638144
	BEAB	Cord Set BEAB (2 cores)	2P	EW302995
	SAA	Cord Set SAA (2 cores)	2P	EW302991
	U/T	Cord Set U/T (2 cores)	2P	EW302899