Apple Multiple Scan 20 Display
| Apple Multiple Scan 20 Display | |
|---|---|
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| Apple Multiple Scan 20 Display (All About Apple museum, Wikimedia Commons, CC BY-SA 3.0) | |
| Manufacturer | Apple Computer, Inc. |
| Type | 20-inch colour CRT display (Trinitron) |
| Release date | March 1994 |
| Discontinued | May 1997 |
| Price | US$2,149 |
| Interface | 15-pin miniature D-type video connector; three ADB ports on the stand |
| Compatible | Power Macintosh, Centris, Quadra, or any NuBus Macintosh with a Display Card 24AC; other Macintosh models at 640 × 480 only |
| Dimensions | 474 × 474 × 501.5 mm (H × W × D) |
| Weight | 30 kg (66 lb) |
| Model | M1823 |
| Power | 90-132 or 198-264 V AC, 47-63 Hz; 165 W maximum |
| Resolution | 640 × 480 to 1280 × 1024 |
The Apple Multiple Scan 20 Display is a 20-inch colour monitor with a Trinitron tube that Apple introduced in March 1994.[1] It scans from 640 × 480 to 1280 × 1024, has a built-in tilt-and-swivel stand with three ADB ports, and is adjusted from a row of buttons on the front panel.[2] Apple's model number on the information tag is M1823.[1] A Rev. B version with a finer 0.26 mm stripe pitch followed.[2] EveryMac gives the introduction as 14 March 1994, alongside the first Power Macintosh models, the price as US$2,149 and discontinuation as 5 May 1997.[3]
Specifications
[edit | edit source]| Item | Specification |
|---|---|
| Picture tube | 20 in diagonal Trinitron CRT, 19.1 in viewable; bonded glass panel with antiglare and antistatic multilayer coating |
| Stripe pitch | 0.31 mm; 0.26 mm on the Rev. B |
| Resolution | 640 × 480 to 1280 × 1024 |
| Scan rates | Vertical 50-150 Hz; horizontal 29-82 kHz; Macintosh, VGA, SVGA and VESA timings |
| Video input | Analogue RGB to RS-343A, 0.714 V peak to peak; sync on green, separate sync or composite sync |
| Power supply | Universal, 90-132 and 198-264 V AC, self-configuring, 47-63 Hz; 165 W maximum, under 15 W in energy-saver mode |
| Size and weight | 474 mm high, 474 mm wide, 501.5 mm deep; 30 kg (66 lb), 36 kg boxed |
| Stand | Built in; tilt −5° to +15°, swivel ±45° minimum; two ADB ports at the front, one at the rear |
| Operating temperature | 10-40 °C |
The display needs a Power Macintosh, Centris or Quadra, or a NuBus Macintosh with a Macintosh Display Card 24AC, and System 7.1 or later. Apple lists the Macintosh II family, PowerBooks, the Duo with Mini Dock, Performa, LC, LC II, LC III and the Display Cards 4•8, 8•24 and 8•24GC as working at 640 × 480 only.[2] Apple's parts list includes a Mac/PC display adapter, 922-0736.[4]
Rev. B
[edit | edit source]The original and the Rev. B look the same. Apple identifies the Rev. B by the last three characters of the serial number: 5B4, 5J2, 5JE or 5JF. The Rev. B has the 0.26 mm stripe pitch and takes its own main deflection board, microprocessor controller board and power supply.[2] The service part numbers differ accordingly:[4]
| Board | Original | Rev. B |
|---|---|---|
| Main deflection board | 661-0506 | 661-0996 |
| Microprocessor control board | 922-0685 | 922-1570 |
| Power supply | 661-0508 | 661-1007 |
| CRT/video board | 661-0507 | 661-0507 |
Hardware
[edit | edit source]Behind the rear housing and the EMI shield the display has a power supply with an AC interconnect board, a main deflection board, a CRT/video board on the neck of the tube, a microprocessor control board, a serial I/O board, a focus control box and an ADB board in the stand.[2] Other service parts are the AC inlet (922-0696), control panel (922-0684), focus VR control (922-0733), serial I/O board (922-0686), base ADB board (922-0687), video cable (922-0732) and tilt/swivel assembly (922-0697). The CRT itself was not offered as a part.[4]
The fuse is on the power supply. The Service Source only says to replace it with one of the same current and voltage rating; Apple's parts list in the service guide gives it as 6.3 A, 250 V (922-0735, packet of ten).[2][4]
Each display keeps its own adjustment data in an EEPROM on the microprocessor control board. Apple's procedure saves it to a file over a mini DIN-8 serial cable before that board is changed and writes it back to the new board afterwards. If the data is lost first, Apple says the display cannot be repaired and has to be replaced.[2][4]
Controls
[edit | edit source]Brightness and contrast have their own plus and minus buttons. A select button cycles through indicator lights for centring, size, rotation, convergence and colour temperature, and the brightness and contrast buttons then adjust the chosen setting. Colour temperature is 9300 K (the default), 6500 K or 5000 K. A recessed reset button, pressed with a straightened paper clip, restores one control or, with the control button held, all of them. The display degausses itself when switched on, and fully if it has been off for 20 minutes or more.[2][5]
Known faults
[edit | edit source]- Apple's own checklist warns that over 60 per cent of returned Multiple Scan 20 modules were found to work. A raster that is bowed, jittery or patchy in colour is often caused by the surroundings: metal furniture, fluorescent lights and other monitors.[2]
- The microprocessor board appears in most of Apple's symptom charts: no picture, a jumping raster, and a blinking convergence, size or centring light. Save the EEPROM settings before changing it.[2]
- A snapping sound with the raster blinking is normal in a new monitor. If it persists past 40 hours of use, Apple lists the power supply, then arcing on the main deflection board, then the CRT.[2]
- A 2025 repair report on TinkerDifferent describes a display that clicked and then gave off smoke. The fuse was intact, and one electrolytic capacitor on the power supply board had a split vent; the owner replaced the capacitors on that board except the large 560 µF 400 V reservoir. The same owner later broke the tube's neck by tipping the 66 lb display to shake dust out of it.[6]
See Apple Multiple Scan 20 Display Troubleshooting Guide for Apple's symptom charts and Apple Multiple Scan 20 Display General Maintenance for the adjustments and take-apart notes. Read CRT Discharge Procedure before opening the display.
Documentation
[edit | edit source]- Apple Multiple Scan 20 Service Source: Apple's 122-page Service Source, covering the original and the Rev. B.
- Apple Multiple Scan 20 Display Documentation: the 1996 user's guide.
- Apple's 1996 service guide Macintosh Displays and Video Cards has a chapter on the display with a parts list and a wiring table (File:Apple Macintosh Displays and Video Cards Service Guide (September 1996).pdf, pp. 111-123).[4]
Related pages
[edit | edit source]- Apple Multiple Scan 20 Display General Maintenance
- Apple Multiple Scan 20 Display Troubleshooting Guide
- CRT Discharge Procedure
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.0 1.1 Apple Computer, Macintosh Displays and Video Cards (service guide, September 1996), hosted as File:Apple Macintosh Displays and Video Cards Service Guide (September 1996).pdf. General Monitor Information: Table 1, model numbers on the information tag (M1823 for the Apple Multiple Scan 20 Display), p. 12 (PDF p. 30); Table 2, dates introduced (Apple Multiple Scan 20, March 1994), p. 13 (PDF p. 31).
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 Apple Computer, Apple Multiple Scan 20 Display (Service Source), 1995, hosted as File:Multiple scan 20 display.pdf (see Apple Multiple Scan 20 Service Source). PDF page numbers: Version Differences pp. 3-4; Monitor Distortion pp. 5-11; EEPROM Settings pp. 12-13; Specifications pp. 15-20; First Checklist pp. 23-25; Display Setting Restoration pp. 26-30; Symptom Charts pp. 31-41; Take Apart pp. 43-97 (EMI shield pp. 48-50, CRT/video board pp. 51-57, power supply pp. 58-62, fuse pp. 63-64); Adjustments pp. 99-120; Exploded View p. 122.
- ↑ EveryMac, "Apple Multiple Scan 20 Display Specs" (retrieved 2026-10-02). Released with the Power Macintosh 6100/60, 7100/66 and 8100/80 and their AV versions; introduced 14 March 1994; discontinued 5 May 1997; original price US$2,149. Community specification list.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Macintosh Displays and Video Cards service guide (1996), Apple Multiple Scan 20 Display chapter: parts list p. 114 (PDF p. 132); board versions and EEPROM settings p. 116 (PDF p. 134); symptom charts pp. 117-121 (PDF pp. 135-139); wiring information pp. 122-123 (PDF pp. 140-141). Hosted as File:Apple Macintosh Displays and Video Cards Service Guide (September 1996).pdf.
- ↑ Apple Computer, Apple Multiple Scan 20 Display User's Guide, 030-8886-A, 1996, hosted as File:Apple Multiple Scan 20 Display User's Guide (1996).pdf (see Apple Multiple Scan 20 Display Documentation). Lifting and positioning the monitor (66 pounds; get help to lift it) p. 5; Adjusting the Picture pp. 23-31; Care and cleaning p. 33.
- ↑ TinkerDifferent forum thread "Recapping the Apple Multiple Scan 20 Display! (Sad Ending)", April 2025. _nec6678: display bought at VCF East, reported as clicking and then letting out smoke; fuse not blown; one capacitor on the power supply board had a split vent; replaced the power supply board capacitors except the large 400 V 560 µF capacitor, using Nichicon parts; tipped the 66 lb display over to shake out dirt and snapped the neck of the tube; afterwards the power lights flashed and the centring indicator was lit. Community repair report.