Apple Monitor III

Apple Monitor III
	A Monitor III on an Apple III at the Apple Museum, Prague
Manufacturer	Apple Computer
Type	12-inch monochrome composite video monitor
Interface	Composite video, RCA phono jack
Compatible	Apple III
Model	A3M0006, A3M0039 (117 V); A3M0024 (230 V)
Power	117 V AC ±10 %, 50/60 Hz, or 230 V AC ±15 %, 50 Hz; 27 W typical, 45 W maximum

The Apple Monitor III is Apple Computer's 12-inch monochrome monitor for the Apple III. Its owner's manual carries a 1981 copyright and lists three model numbers: A3M0006 and A3M0039 for 117 V supplies and A3M0024 for 230 V.^[1] The monitor connects to the Apple III's black-and-white video output with a phono cable. A microporous nylon glare filter rests in front of the screen.^[2]

The monitor contains a CRT. Read CRT Discharge Procedure before opening it.

Specifications

**Monitor III specifications (owner's manual, p. 6)**^[1]
Item	Value
Picture tube	12 in (30.5 cm) diagonal; 78° horizontal, 61° vertical, 90° diagonal deflection
Video input	Composite, 1.0 V p-p ±0.1 V, sync negative, RS-170 compatible; 75 Ω internal termination; RCA phono jack on the cabinet
Video amplifier	50 Hz to 15 MHz ±3 dB; 16 discernible shades of grey
Vertical deflection	47 to 63 Hz free-running; pull-in range +0 −8 Hz; linearity within 2 %
Horizontal deflection	15,200 to 16,300 Hz free-running; pull-in range ±400 Hz; linearity within 2 %
Resolution	700 TV lines at centre, 500 at the corners
Maximum brightness	40 fL (A3M0006); 20 fL (A3M0039, A3M0024)
Display zone	21.4 cm × 16 cm; 80 characters × 24 lines
Power	117 V AC ±10 %, 50/60 Hz (A3M0006, A3M0039) or 230 V AC ±15 %, 50 Hz (A3M0024); 27 W typical, 45 W maximum; internal fuse
Dimensions	43.7 cm wide, 27 cm high, 31.8 cm deep
Weight	7.5 kg (16.5 lb)

The power switch and contrast knob are on the front; brightness, vertical hold and vertical size are on the back, with a hand grip for lifting.^[2]

Hardware

Sams's ComputerFacts for model A3M0039 (folder CMT8-1, March 1985) describe a single main board with a regulated supply: AC fuse F901, bridge diodes D901-D904, a series regulator transistor Q901 with IC901, and a DC fuse F902. The B+ control R903 sets 11.6 V at the collector of Q901. The horizontal output transistor Q701 drives the flyback T702, which contains the high-voltage rectifier and also supplies 58.5 V through D252 for the video stage. The vertical stage is an IC (IC601).^[3] A beam current limiter transistor (Q253) protects the screen from burning during long use.^[3]

Apple's own schematic of the monitor is printed at the back of the owner's manual, which tells owners to keep it with the manual.^[1]

Service by Apple

Apple did not repair the Monitor III in the field. Its Technical Procedures, revised in October 1988, tell the technician not to attempt any repair or adjustment: a defective unit is exchanged for one from service stock, with the customer's serialised rear cover moved onto the replacement and the failed unit returned to Apple. From June 1988 units serviced in Australia went back to Apple as complete systems.^[4] Board-level information comes from the Sams folder and Apple's schematic. See Apple Monitor III General Maintenance and Apple Monitor III Troubleshooting Guide.

Documentation

The owner's manual (two scans), Apple's Technical Procedures and Sams's ComputerFacts are hosted and described on Apple Monitor III Documentation.

Related pages

Apple Monitor III General Maintenance
Apple Monitor III Troubleshooting Guide
Apple Monitor III Documentation
Apple III
Apple Monitor II, the green-screen monitor for the Apple II family
CRT Discharge Procedure

References

↑ ^1.0 ^1.1 ^1.2 Apple Computer, Monitor III Owner's Manual, 1981, A3L0020, 030-0193-A, Specifications, p. 6. Hosted here: File:Apple Monitor III Owner's Manual 1981.pdf.
↑ ^2.0 ^2.1 Monitor III Owner's Manual, pp. 1-5 (safety tips, controls, glare filter care and the problem chart). Second hosted scan: File:Apple Monitor III Owner's Manual 1981 (second scan).pdf.
↑ ^3.0 ^3.1 Howard W. Sams & Co., ComputerFacts CMT8-1, Apple Model A3M0039, March 1985, Troubleshooting Aid and Miscellaneous Adjustments, p. 4, and Troubleshooting, p. 5 (PDF pp. 7-8). Hosted here: File:Sams ComputerFacts CMT8 Apple Monitor III A3M0039.pdf.
↑ Apple Computer, Monitor III Technical Procedures, Section 1, Monitor III Exchange, revised October 1988, pp. 1.3-1.9, with the June 1988 Australian revision notice, in Apple Service Technical Procedures: Apple II/Apple III Archived Products, Volume One, 072-0231 (PDF pp. 4-14). Hosted here: File:Apple Monitor III Technical Procedures.pdf.

[om-1] 1.0 ^1.1 ^1.2 Apple Computer, Monitor III Owner's Manual, 1981, A3L0020, 030-0193-A, Specifications, p. 6. Hosted here: File:Apple Monitor III Owner's Manual 1981.pdf.

[om2-2] 2.0 ^2.1 Monitor III Owner's Manual, pp. 1-5 (safety tips, controls, glare filter care and the problem chart). Second hosted scan: File:Apple Monitor III Owner's Manual 1981 (second scan).pdf.

[sams-3] 3.0 ^3.1 Howard W. Sams & Co., ComputerFacts CMT8-1, Apple Model A3M0039, March 1985, Troubleshooting Aid and Miscellaneous Adjustments, p. 4, and Troubleshooting, p. 5 (PDF pp. 7-8). Hosted here: File:Sams ComputerFacts CMT8 Apple Monitor III A3M0039.pdf.

[tp-4] Apple Computer, Monitor III Technical Procedures, Section 1, Monitor III Exchange, revised October 1988, pp. 1.3-1.9, with the June 1988 Australian revision notice, in Apple Service Technical Procedures: Apple II/Apple III Archived Products, Volume One, 072-0231 (PDF pp. 4-14). Hosted here: File:Apple Monitor III Technical Procedures.pdf.

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