Routine Maintenance and Conversion Information

5-1 ROUTINE MAINTENANCE↑ TOP

It is important tnat routine maintenance be performed at the recommended intervals.

Exterior cleaning and demagnetization should be performed after every eight hours of operation, and the interior of the transport should be cleaned once a month.

Lubrication should be performed after 1,000 hours of operation or after 6 months, whichever comes first.

5-1-(1) CLEANING↑ TOP

Oxide particles from the magnetic tape tend to collect on components in the tape path and degrade the performance of the recorder.

To clean the head assembly, proceed as follows:

1. Disconnect the power cable from the power supply.
2. Lift the head cover as shown in Figure 5-1.

CAUTION

WHEN CLEANING THE HEADS, USE THE RECOMMENDED SOLVENT (HEAD CLEANER) ONLY TO AVOID DAMAGING THE HEADS.
KEEP THE HEAD CLEANER OFF PLASTIC FINISHES AND THE CAPSTAN PINCH ROLLER.
DO NOT USE METAL TOOLS THAT COULD SCRATCH THE HEADS.

3. Clean each head thoroughly with a cotton-tipped applicator (Q tip) dampened with head cleaner.
4. Use isopropyl alcohol to clean all tape-guiding components; the capstan shaft, and the capstan pinch roller.

CAUTION

1. DO NOT USE A HEAD CLEANER ON THE CAPSTAN PINCH ROLLER, SINCE THIS WILL CAUSE DAMAGE AND TAPE SLIP.

2. BEFORE REMOVING THE REAR COVER, THE PLUG MUST BE DISCONNECTED FROM THE POWER SUPPLY TO AVOID AN ELECTRIC SHOCK.

3. Place the recorder on its side, and remove the six screws on the bottom cover. After that, remove the four screws, and open the Control P.C. Board. (Refer to Figure 5-8)

4. Use a vacuum cleaner and a small brush to remove all dust or contamination from the interior of the transport. If necessary lightly moisten brush with isopropyl alcohol to clean parts.

5. Install the bottom cover and the Control P.C. Board Ass'y.

⤢ zoomThe head housing with its cover, which carries the OTARI logo, and a curved arrow at the cover's front edge showing it being lifted up and back off the heads.

Figure 5-1 Lifting the Head Cover

5-1-(2) DEMAGNETIZING↑ TOP

The heads and tape guiding components in the tape path should be demagnetized after every eight hours of operation.

These components can acquire permanent magnetization that increases noise and distortion, and partially erases high frequencies on recorded tapes.

Use a hand-held head demagnetizer to demagnetize all components in the tape path as follows:

1. Turn equipment power off and move any recorded tape near tne transport away (tape could be partially erased by the demagnetizer).
2. Lift the head cover as shown in Figure 5-1.
3. Cover the demagnetizer tips with an adhesive tape to prevent scratching the head stacks.
4. With the demagnetizer at least three feet away from the transport, connect the demagnetizer to a power source.
5. Slowly move the demagnetizer tips close to the head, lightly touch the demagnetizer tips to the face of one head stack and slowly move the tips up and down at the entire face of the stack several times. Then slowly withdraw the demagnetizer as shown in Figure 5-2.
6. Repeat step 5 for each head stack.
7. Repeat the motions in step 5 for each guide and other metallic parts in the tape path.
8. Slowly move the demagnetizer at least three feet away from the transport and then disconnect the power from the demagnetizer.

⤢ zoomThe head assembly with its cover raised and a demagnetizer held with its tips against the face of a head stack, labelled DEMAGNETIZER.

Figure 5-2 Demagnetizing

5-1-(3) LUBRICATION↑ TOP

The only components requiring lubrication are the capstan sleeve bearing.

Refer to Figure 5-3 and proceed as follows:

CAUTION

1. DO NOT USE ANY OIL EXCEPT ANDEROL #456 FOR LUBRICATION.

2. BE CERTAIN TO CLEAN THE CAPSTAN SHAFT THOROUGHLY. LUBRICATING OIL COULD RUIN THE CAPSTAN PINCH ROLLER AND MAGNETIC TAPE. CLEAN THE CAPSTAN WITH ISOPROPYL ALCOHOL AFTER LUBRICATION.

3. Remove the pinch roller cap by removing the screw on it.

4. Remove the pinch roller from the pinch roller shaft.

5. Remove two hex socket head screws on the head housing cover. Remove the head front escutcheon by removing the two screws on it and remove the head rear escutcheon by removing the three screws on it. Turn the Dust Cap counterclockwise and pull off from the capstan.

6. Apply 2 or 3 drops of oil to this felt collar. Do not over lubricate.

7. Wipe off any excess oil and install the dust cap, head front escutcheon, head rear escutcheon, and pinch roller cap in the reverse order.

⤢ zoomAn exploded view of the pinch roller assembly: the screw and pinch roller cap, the pinch roller, the dust cap turned off the capstan, and an oiler pointed at the felt collar round the capstan's base.

Figure 5-3 Lubrication

5-2 TAPE REPLACEMENT↑ TOP

The MX-5050 MK III-4 is set at the factory for Scotch #226 Recording Tape.

If another tape is to be used, the following adjustment may be required for optimum tape performance.

Refer to Section 7.

Required adjustments are:

1. The record bias adjustment.
2. The record level adjustment.

5-3 EQUALIZER CHANGE↑ TOP

The equalizer between the NAB or the IEC can be changed by replacing the RECORD/REPRODUCE Amplifier P.C. Board Ass'y.

However, a fine equalizer adjustment and a record level set are required.

Refer to Section 7 to aid the fine adjustment.

Table 5-1 Record Level

Reference fluxivity	Relative level	Test Tape	Recording tape to be used
185 nWb/m*	0 dB	Ampex Operating level	Scotch 177, Ampex 641
250 nWb/m*	+2.6 dB	MRL NAB standard	Scotch 206,207,226,250 Ampex 406,407,456
320 nWb/m**	+3.8 dB	BASF or MRL IEC Standard	IEC Equalization

* Short circuit flux.

** Open circuit flux.

5-4 LINE VOLTAGE CONVERSION↑ TOP

The line voltage is converted by resoldering the wiring on the voltage selection terminal, proceed as follows:

1. Remove two flat head socket cap screws putting the ventilation channel. Remove four cross-recessed screws on the top ventilation cover (with transport rear panel) from the rear of the equipment.
2. Draw out three connectors of ERASE/RECORD HEAD, REPRODUCE HEAD, TO AMP. And after placing the equipment on it's side and removing six cross-recessed screws on the bottom cover, remove last two cross-recessed screws on the top ventilation cover. (Refer to Figure 5-5.)
3. Resolder the lead wire of the voltage selection terminal on the supply reel Ass'y to the desired voltage terminal marked as shown in Figure 5-4.

⤢ zoomThe voltage selection terminal board, with tabs marked LIVE, 100V, 117V, 220V and 240V, a jumper wire from LIVE to the 117V tab, and a note that it is connected for 117V.

Figure 5-4 Voltage Selection Terminal

⤢ zoomThe recorder's chassis seen from the rear with covers removed, showing the internal wiring access for the voltage conversion.

Figure 5-5 Access for Line Voltage Conversion

5-5 FUSE REPLACEMENT↑ TOP

If a fuse is blown, it is important that the possible cause is checked before replacing the fuse.

CAUTION

FOR CONTINUED PROTECTION AGAINST FIRE HAZARD, REPLACE ONLY WITH THE SAME TYPE OF FUSE.
BEFORE REPLACING THE FUSE, REMOVE THE POWER CORD FROM THE POWER SOURCE.

Information concerning the seven fuses can be found in Table 5-2.

For the main power fuse (FS801), proceed as follows:

1. Place the equipment on its side. Remove six cross-recessed screws putting the bottom cover. Remove four cross-recessed screws marked "OPEN" on the Control P.C. Board. And open the Control. P.C. Board.
2. Replace the main power fuse (FS801) on the power switch P.C. Board.

⤢ zoomThe power switch P.C.B. outline, labelled POWER SWITCH P.C.B., with the REEL, SPEED and POWER switches SW803, SW802 and SW801 along its top edge and the main power fuse FS801 3A at its right-hand end.

Figure 5-6 Main Power Fuse Location

For other fuses (F1~F6), proceed as follows:

1. Place the equipment on its side and remove six cross-recessed screws putting the bottom cover.
2. Remove four cross-recessed screws marked "OPEN" on the Control P.C. Board.
3. Pull the Control P.C. Board down, and replace the blown fuse.

Table 5-2 Fuse Information

Reference number	Current	Rating voltage	size(inch,mm)	carry	blow	Otari part number	Used for
FS801	3A	250V	1/4x1 1/4 inch 6.3x32mm	110%	135% in 1 hour	FH7E030	Primary Circuit
F1	1A	"	13/64x45/65 inch[sic] 5x20mm	"	" " "	FH7F010	VU Meter Lamps
F2	2A	"	" " " " " "	"	" " "	FH7F020	DC Servo Cap. Motor Driver
F3	"	"	" " " " " "	"	" " "	"	Pinch roller Solenoid, Relays, and DC Servo Cap. Motor Control
F4	"	"	" " " " " "	"	" " "	"	±15V Amplifier
F5	"	"	" " " " " "	"	" " "	"	"
F6	"	"	" " " " " "	"	" " "	"	Brake Solenoids, +5V Transport Control LEDs

⤢ zoomThe control P.C.B. outline, labelled CONTROL P.C.B., with fuses F1 to F6 grouped along its lower edge and two round trimmer components above them.

Figure 5-7 Internal Fuse Location

⤢ zoomThe recorder's chassis seen from the rear with the cover off, the control P.C. board folded down on its lower hinge edge as a curved arrow shows.

Figure 5-8 Rotating Control P.C.B.