RetroTechCollection

Apple Two-Page Monochrome Monitor General Maintenance

Care, take-apart and adjustment notes for the Apple Two-Page Monochrome Monitor, from Apple's Service Source and service guide. Apple gives exact raster sizes and a luminance target for this display, and lists the fuse rating.[1]

Apple's exploded view of the Two-Page Monochrome Monitor with service part numbers (Service Source, PDF p. 98)

Safety

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Discharge the CRT before working on any board; Apple's video board, deflection board, power supply and fuse procedures all begin with it, and warn not to wear a wrist strap until it is done. Follow CRT Discharge Procedure. The geometry and video adjustments are made from the rear with the display running: use a mirror to watch the screen and do not reach round the display. Apple says to set the three-position switch with a plastic alignment tool, or to switch the display off before reaching in to set it, and not to touch the heatsink.[1] The display weighs 25 kg (55 lb).[1]

Before adjusting

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Large screens are disturbed by metal furniture (at the edges of the picture) and by fluorescent lights, other monitors and appliances (movement and jitter). Apple's note is that adjusting a display to cancel these changes its factory settings and swapping modules will not fix them. Move or swivel the display, or check it in another building, first. A picture shifted only up, down or sideways can be corrected with the centring controls.[1]

Take-apart notes

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  1. Stand: tip the display onto its left side, slide the stand towards the bezel, lift the display slightly and turn the base until the three screws can be reached, remove them and slide the stand off. The stand must come off before the CRT.
  2. Rear cover: four screws. Access cover: six screws with lock washers.
  3. Discharge the CRT.
  4. Video board: unplug J601 (13-wire), J602 (11-wire), J603 (6-wire) and J604 (2-wire, red/orange), remove the nut, washer and green ground wire from the post on the chassis floor, pull the CRT socket off the neck, remove four screws and lift the board out.
  5. Deflection board: remove the anode cap and four screws, then unplug J402 (11-wire), J202 (3-wire, red/blue), J501 (2-wire, red/orange), J201 (5-wire), J401 (13-wire), J403 (2-wire, grey) and J301 (2-wire, yellow/black). Free the bleeder resistor on the chassis floor: a cigar-shaped one slides sideways out of its plastic clip, a box-shaped one is held by a screw. Take the anode wire out of its clamp and lift the board out.
  6. Power supply: two screws, then the three-wire connector on top and the five-wire connector at the front.
  7. Fuse: on the power supply board; prise one end up and lift it out.[1]

Apple warns not to pull connectors apart by their wires; if a connector sticks, separate its halves with a jeweller's screwdriver.[1]

Fuse rating

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The correct fuse is 2.5 A. Apple notes that some displays with serial numbers between 43661GXW and 44718HQX left the factory with a 1.6 A fuse, which is the wrong value. The service guide lists the part as 2.5 A, 250 V, 941-0016.[1][2]

Geometry

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Remove the rear cover and access cover. Do the geometry adjustments whenever the CRT, deflection board or video board is replaced.[1]

Apple's geometry procedure[1]
Step Pattern Control and target
Horizontal linearity Crosshatch II (white background) Horizontal linearity coil, turned only with the linearity adjustment tool; Apple warns any other tool can damage the core or short the circuit. Make the raster as wide as possible, then make the left and right halves equal, measured with a flexible ruler from the centre line.
Horizontal size Crosshatch II Raster width 15 in ± 1/8 in (381 ± 3 mm); recheck the two halves.
Three-position switch Crosshatch II If the boxes at the sides differ in size from those in the centre, try each position of the switch and keep the best, then reset the width to 15 in.
Horizontal shift Crosshatch II Raster centred.
Vertical linearity Crosshatch I or II First the orange capacitor at C306 so that the top two rows of boxes match, then the vertical linearity control so that the top and bottom rows match.
Vertical shift Full white screen White raster centred vertically.
Vertical size All-white screen Raster height 11 5/16 in ± 1/8 in (287.3 ± 3 mm).
Focus Focus pattern Static focus for the centre box, horizontal focus for the left and right boxes, vertical focus for the top and bottom; repeat.

Video

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Remove the rear cover and access cover. Do the video adjustments whenever the CRT, deflection board or video board is replaced. Work in a dimly lit room.[1]

  1. Switch off and unplug the video cable. Set the external contrast to maximum and brightness to its centre detent, and turn the cutoff control fully anticlockwise.
  2. Switch on and wait 20 minutes. If the power is off for more than a few seconds afterwards, wait another 20 minutes.
  3. On the all-white screen, turn cutoff clockwise until a white raster just appears, then back until it just fades to black.
  4. Switch off, reconnect the video cable and switch on. On the grey bars, set cutoff so that the darkest bar is black and the next is barely distinguishable from it.
  5. On the all-white screen, set the sub-contrast control with a light meter for 31 foot-lamberts ± 3.
  6. Turn the external brightness knob to maximum and set the brightness range control for 31 fL ± 3, then return the knob to its detent.[1]
Meter readings for 31 fL ± 3[1]
Meter Reading
R77 (Apple 076-0310) 23 on the bottom scale, with the 10× multiplier plate removed
L-248 Middle of the 10 scale
246 23 on the red scale

Apple says readings from the three meters differ, that meter accuracy drifts with age, and that a dropped meter may read wrongly; check a doubtful meter against a known-good one.[1]

Stand

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If the stand will not swivel, check that the "Front" mark on the tilt/swivel mechanism lines up with the one on the base and that the snap-lock assembly under the stand is in place. If it will not tilt, check the plastic plug in the snap-lock assembly.[1]

Capacitors

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Apple's documents for this display are module-level and give no capacitor values. The vertical linearity procedure adjusts an orange capacitor at C306 with a plastic alignment tool.[1] See Capacitor Failure Symptoms.

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References

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  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 Apple Computer, Apple Two-Page Monochrome Monitor (Service Source), 1995, hosted as File:Twopage monochrome monitor.pdf (see Apple Two-Page Mono Service Source). PDF page numbers: Monitor Distortion pp. 3-9; Take Apart: swivel stand pp. 26-28, rear cover p. 29, access cover p. 30, video board pp. 31-35, deflection board pp. 36-41, power supply pp. 42-44, fuse pp. 45-46, on/off switch pp. 47-49, contrast/brightness assembly pp. 50-53, bezel pp. 54-55, CRT pp. 57-61; Adjustments: geometry pp. 65-79, video pp. 80-90, light meter set-up pp. 91-96.
  2. ↑ 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. Apple Two-Page Monochrome Monitor chapter, parts list p. 310 (PDF p. 328): fuse 2.5 A 250 V (pkg. of 5), 941-0016; deflection board 661-0451; video board 661-0452; power supply 661-0453; on/off switch filter assembly 937-0040; CRT assembly 076-0320; tilt swivel monitor stand 815-0558.


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