Apple Portrait Display General Maintenance
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Care, take-apart and adjustment notes for the domestic version of the Apple Portrait Display, from Apple's Service Source and service guide. Apple published full geometry and video procedures for this display, with measurements and light-meter readings. The international "Series B" version is built differently and is not covered here.[1]
Safety
[edit | edit source]The CRT and the power/sweep board carry dangerous voltages, and Apple's take-apart steps discharge the CRT before any board is touched. Follow CRT Discharge Procedure. All of Apple's adjustments are made from the rear with the display running: watch the screen in a mirror, do not reach round the display, and use a plastic screwdriver. Switch the display off before connecting or removing clip leads on test points, to avoid a short.[1]
Before adjusting
[edit | edit source]Rule out the surroundings first. Apple lists metal desks, filing cabinets and bookshelves, which distort the edges of the picture, and fluorescent lights, other monitors and appliances, which make it move or jitter. Adjusting a display to cancel these changes its factory settings, and swapping modules will not cure them. Swivel or move the display, or check it in another building; if the picture changes, the location is the cause.[1]
Take-apart notes
[edit | edit source]- The EMI shield is two metal panels, at the top and at the rear of the chassis; remove both for repairs.[1]
- The fuse is on the AC input assembly. Remove the rear cover and EMI shield, discharge the CRT, lift the AC input assembly out after unscrewing its black ground wire, unplug its P connector from the power/sweep board, and prise one end of the fuse up. Apple's parts list gives the fuse as 4 A, 250 V (941-0017). When returning a faulty AC input assembly, Apple's technicians kept the on/off knob, the P connector and the fuse for the replacement.[1][2]
- The fan is held by a bracket screwed to the chassis, with its wires in four cable clamps.[1] One owner notes that it is barely audible.[3]
- The CRT board is pulled straight off the neck of the tube after loosening its ring clamp. Apple warns that twisting or bending it can break the neck; support the board while unplugging its upper connectors.[1]
- The power/sweep board stays in its plastic cover; Apple says not to separate them. It comes out after the anode cap, the AC input assembly and the large red anode cable have been freed.[1]
- Lift the CRT by its sides, never by the neck.[1]
Geometry
[edit | edit source]Remove the rear cover. Apple's note is that geometry may need adjusting whenever the power/sweep board is replaced. Use the Display Service Utility patterns named below.[1]
| Control | Pattern | Target |
|---|---|---|
| H.Size (horizontal size) | All-white screen | Raster width 8 in ± 1/8 in (203 ± 2 mm) |
| H.Cent (horizontal centre) | All-white screen | Centred left to right; recheck the width |
| H.Phase (horizontal phase) | All-white screen | Black margin on the right, from the edge of the white raster to the bezel, of 1/4 in (7-8 mm) |
| Height | All-white screen | Raster height 10 7/8 in ± 1/8 in (276 ± 2 mm) |
| V.Cent (vertical centre) | All-white screen | Centred top to bottom; recheck the height |
| V.Lin (vertical linearity) | Crosshatch | Boxes at the top the same size as those at the bottom |
| Focus, H.F. and V.F. | Focus pattern; contrast at maximum, brightness at its centre detent | Focus for the best overall focus, H.F. for the left and right edges, V.F. for the top and bottom; repeat until no further gain |
Video
[edit | edit source]Do the video adjustments whenever the CRT or video board has been replaced, or when the picture looks misadjusted. Remove the rear cover and EMI shield, and refit the signal input board with its two mounting screws before starting. Let the display warm up for at least 10 minutes. Apple gives two procedures: one for displays with a Screen control, and one for displays without; check which yours has.[1]
Displays with a Screen control
[edit | edit source]- Preset the Screen control to maximum, GAIN to its midpoint and SUB-BRIGHT to maximum.
- Cutoff: show the all-black screen with contrast and brightness at maximum. Turn the cutoff control clockwise until retrace lines just appear, then back until they just disappear. If the display shuts down because cutoff is too high, switch off, turn cutoff fully down, wait 30 seconds and start again.
- Sub-brightness: show the grey bars with brightness at its centre detent, and set SUB-BRIGHT so that the leftmost bar is completely black.
- Screen luminance: show the all-white screen and set 40 foot-lamberts ± 3 with the light meter. With brightness at its centre, the reading must not go above 60 fL. Repeat the SUB-BRIGHT and GAIN settings until both readings are right.[1]
Displays without a Screen control
[edit | edit source]- Bias: preset SUB-BRIGHT to minimum, show the all-black screen and set brightness and contrast to minimum. Switch off. Connect shielded clip leads from TP1 (positive) and TP2 (negative) on the CRT board to a good DC voltmeter. Switch on and turn the BIAS control until the meter reads 55 V DC ± 1.0 V. Switch off before removing the leads.
- Cutoff: set brightness and contrast to maximum and SUB-BRIGHT to its midpoint. On the grey bars (16 shades), turn the cutoff control until the leftmost bar is completely black. Set brightness back to its detent. The same shutdown warning applies.
- Screen luminance: on the all-white screen, set GAIN for 40 fL.[1]
Light-meter readings
[edit | edit source]Apple's procedures use three light meters, which read differently. Remove the 10× multiplier plate from the R77 and read its bottom (10-50 fc) scale; check its four-digit date stamp, and treat a dropped meter as suspect.[1]
| Target | R77 (Apple 076-0310), bottom scale | L-248, 10-18 scale | 246, red scale |
|---|---|---|---|
| 40 fL ± 3 | 29 | 10 to 11 | 29 |
| 60 fL maximum | 40 | 11 to 12 | 40 |
Capacitors
[edit | edit source]Apple's documents give no capacitor values for this display. One owner counted 35 electrolytics on the power/sweep board and 31 on the video board and replaced them all; another, recapping as a precaution, found several leaking.[3][4] Members point out that the neck and sweep boards use 105 °C parts and that replacements should match the originals' ratings.[3] See Capacitor Failure Symptoms.
Related pages
[edit | edit source]- Apple Portrait Display
- Apple Portrait Display Troubleshooting Guide
- Macintosh Portrait Display Service Source
- CRT Discharge Procedure
References
[edit | edit source]- ↑ 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 1.15 Apple Computer, Macintosh Portrait Display (Service Source), 1995, hosted as File:Portrait display.pdf (see Macintosh Portrait Display Service Source). PDF page numbers: International "Series B" p. 3; Monitor Distortion pp. 4-7; Take Apart: rear cover pp. 25-26, EMI shield pp. 27-29, AC input assembly pp. 30-32, fuse pp. 33-34, signal input assembly pp. 35-37, fan pp. 38-40, video board pp. 41-45, contrast/brightness board pp. 46-47, CRT board pp. 48-54, power/sweep board pp. 55-59, bezel pp. 60-62, CRT pp. 67-70; Adjustments: monitor safety p. 72, light meter set-up pp. 73-78, geometry pp. 79-87, video with screen control pp. 88-96, video without screen control pp. 97-106.
- ↑ 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. Macintosh Portrait Display chapter: main circuit boards p. 291 (PDF p. 309); parts list p. 292 (PDF p. 310), including fuse 4 A 250 V (941-0017), power/sweep board 661-0117, video board 661-0118, CRT video board 661-0119, fan 983-0014, CRT assembly 076-0350, adjustment magnet kit 949-0253.
- ↑ 3.0 3.1 3.2 TinkerDifferent forum thread "Macintosh Portrait Display Repair - Smearing/Pulsing Image on Screen", October 2021 to July 2026. warmech: recapped the power/sweep board (35 capacitors) and the video signal board (31 capacitors); the video board recap cured a smeared, pulsing picture. naruse (December 2024): the neck and sweep boards originally used 105 °C capacitors and the signal board 85 °C; the fan inside is barely noticeable. JDW: recommends matching the original capacitor ratings, including temperature, when in doubt. Community repair report.
- ↑ TinkerDifferent forum thread "Portrait display maintenance", July 2026. jmacz: recapped his working display and found a few capacitors leaking. iantm: a part on the earlier list is discontinued, and the display exists in revisions that may need different parts. Community experience.