Apple High Resolution Monochrome Monitor General Maintenance
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Take-apart notes, the fuse and Apple's adjustment procedures for the Apple High-Resolution Monochrome Monitor, from Apple's Service Source.[1] Apple gives no anode voltage for this monitor. Treat the tube as charged and read CRT Discharge Procedure first; never wear a grounding wrist strap until the CRT has been discharged.[2]
Take-apart notes
[edit | edit source]- Rear cover: four case screws.[3]
- Main board: four screws to the chassis, then take the anode wire out of its cable clamp. Connectors D2, D4, D5 and D9 are tight and hard to reach, so pull the board away from the chassis before unplugging them. The others are D7 (large 3-pin), D8 (large 4-pin) and D6 (large 6-pin).[4]
- Power supply: unplug its 6-pin and 3-pin connectors (the 3-pin may need tie-wraps cut and the chassis lifted to reach it), release the CRT ground wire from the clamp on its side, remove two screws and lift it until its tabs clear the chassis.[5]
- Video board "C": it sits in a metal box on the tube neck. Support the board while loosening the clamp screw, cut any sticky tape under the clamp carefully with a knife without pressing on the neck, and pull the board straight off. Twisting or bending it can break the tube neck. An exchange board goes back to Apple without the back cover of the box, which stays with the monitor.[6]
- CRT: after the video board, unplug D9, remove the six chassis screws and pull the chassis off the bezel, then the four CRT screws. Move the ground strap and spring to a replacement tube.[7]
Fuse
[edit | edit source]The fuse is inside the power supply housing. Remove the power supply, take out the two screws on the sides of the housing and the one in the indentation underneath, and slide the board out. Replace the fuse with a 250 V 2 A part (Apple 740-0305).[8][9] When refitting, the board must slide into the middle slot on the side of the housing and must not touch the bottom.[8]
Adjustments
[edit | edit source]Adjust from the rear with a mirror in front of the screen; Apple says not to reach round the monitor. Do not attempt yoke adjustments. Test patterns come from Apple's Display Service Utility.[10]
Geometry and focus
[edit | edit source]Needed after a main board, CRT or video board change. Set contrast to maximum and brightness to its centre detent.[10]
| Adjustment | Pattern | Target |
|---|---|---|
| Horizontal size (always first; it affects the height) | Crosshatch II, white background | Raster 8.4 in (213.5 mm) wide |
| Vertical size | Crosshatch II | Raster 6.3 in (160 mm) high |
| Focus | Focus pattern | Best clarity at the centre of the screen |
Video
[edit | edit source]Needed after a contrast control board, main board or video board change. Remove the rear cover and connect video and power.[11]
- Set the subcontrast control midway between its stops with a two-inch plastic screwdriver.
- Set the Monitors control panel to 16 greys and display the Gray Bars pattern. Contrast to maximum, brightness to its centre detent.
- Adjust the cutoff control (RV506) until the leftmost bar is black and the second bar just visible. If the monitor shuts down because cutoff was turned too far clockwise, switch off, turn cutoff fully anticlockwise, wait 30 seconds and start again.
- Display the All-White Screen pattern and adjust for 33 foot-lamberts ±3 on the light meter: 25 on the bottom scale of the R77 (Apple 076-0310), the middle of the 10 scale on the L-248, or 25 on the red scale of the 246.
The three meters read differently; set them up as the Service Source describes (R77 bottom 10-50 fc scale with the 10X plate removed; L-248 battery check with the red button; 246 with the white lens with the red dot). A dropped meter can read wrongly.[12]
Apple's 1987 Technical Procedures cover the same ground with a sub-brightness (cutoff), horizontal size, vertical size and focus procedure, and add rules for live adjustments.[13]
Related pages
[edit | edit source]- Apple High Resolution Monochrome Monitor
- Apple High Resolution Monochrome Monitor Troubleshooting Guide
- Apple High-Res Service Source
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ Apple Computer, Apple High-Resolution Monochrome Monitor (Service Source), 73 pp. Hosted here: File:Highres monochrome monitor.pdf (see Apple High-Res Service Source). Page references are the Service Source's own, with the PDF page in brackets.
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Take Apart, Main Board, p. 2 (PDF p. 17).
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Take Apart, Rear Cover, p. 1 (PDF p. 16).
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Take Apart, Main Board, pp. 2-7 (PDF pp. 17-22).
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Take Apart, Power Supply, pp. 8-10 (PDF pp. 23-25).
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Take Apart, Video Board C, pp. 17-24 (PDF pp. 32-39).
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Take Apart, CRT, pp. 25-28 (PDF pp. 40-43).
- ↑ 8.0 8.1 Apple High-Resolution Monochrome Monitor Service Source, Take Apart, Fuse, pp. 11-13 (PDF pp. 26-28).
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Exploded View (PDF pp. 72-73).
- ↑ 10.0 10.1 Apple High-Resolution Monochrome Monitor Service Source, Adjustments, pp. 1-15 (PDF pp. 51-65).
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Adjustments, Video, pp. 8-15 (PDF pp. 58-65).
- ↑ Apple High-Resolution Monochrome Monitor Service Source, Adjustments, Light Meter Setup, pp. 16-21 (PDF pp. 66-71).
- ↑ Apple Computer, High-Res Monochrome Monitor Technical Procedures, 1987, Section 1 (CRT safety and live adjustment rules) and Section 3 (Adjustments). Hosted here: File:Apple High-Res Monochrome Monitor Technical Procedures.pdf.