RetroTechCollection

Apple Studio Display 17 General Maintenance

Care, take-apart and adjustment notes for the 1999 Apple Studio Display 17 (M6221LL/A and /B), from Apple's Service Source and the chassis maker's service manual. Apple's checks give a figure for every stage of the high-voltage and video supplies. The 2000 ADC model is a different chassis with its own Service Source.[1]

Apple's exploded view of the Studio Display (17-inch CRT) with service part numbers (Service Source, PDF p. 128)

Safety

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The CRT holds a dangerous charge after the display is switched off and unplugged. Apple's rule is that whenever the EMI shield is off and before any module is replaced:[1]

  1. Discharge the CRT with the discharge tool (Apple 076-0381): clip to the CRT frame, needle under the anode cap.
  2. Remove the anode cap.
  3. For work inside with the power off, fit an ongoing ground: a clip lead from the anode aperture to the ground strap round the CRT. Only then wear a wrist strap.

Follow CRT Discharge Procedure. Apple's voltage checks are made with the covers off and the display running: connect and remove probes only with the power off, keep hands away from the CRT/video board pins, and watch the screen in a mirror instead of reaching round the display.[1] The edges of the EMI shield and chassis are sharp.[1]

Housing and stand

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  • Lift the display by the hand grips under its sides, never by the tripod stand, and do not move it by pulling the legs; Apple warns the stand cracks if mishandled. Stand it with all three feet on the surface, clear of the table edge.[1]
  • The translucent plastic scratches easily. Work on a clean protective pad, keep metal tools off the housing, and rest the display face down on a thick book or ream of paper.[1]
  • The rear housing carries part of the weight of the chassis and CRT. With it removed, do not stand the display upright and avoid moving it.[1]
  • The rear housing is two moulded pieces, coloured top and clear bottom; do not try to separate them.[1]
  • Housing parts are colour-specific: the blue version (M6221LL/A) uses rear housing 922-3649, intermediate bezel 922-3647 and front bezel 922-3651; the grey version (M6221LL/B) 922-3937, 922-3936 and 922-3938.[1]
  • The serial number and manufacturing date are on a label on the back of the tripod stand. A replacement stand comes with the label blank; copy the details across.[1]

Take-apart notes

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Apple's tools: a protective pad and a thick book, a magnetic Phillips screwdriver (Apple prefers an electric one) with a 6-inch extension, the CRT discharge tool, a flat-blade screwdriver, wire cutters and a cable tie for the convergence/tilt board cables.[1]

  1. Intermediate bezel: with the display upright, work fingers under its lower edge, release the back tabs and slide it up off its hooks, one side at a time; release the front tabs with a broad (3/8 in) flat blade between it and the front bezel. The tabs are fragile.
  2. Tripod stand: lay the display face down, remove the eight Phillips screws, taking the two beside the serial number label out last, and tilt the stand away. When refitting, tighten each screw half way, check that the control buttons line up with the holes in the stand, then tighten fully.
  3. Rear housing: six Phillips screws; lift it straight off and feed the video cable through.
  4. EMI shield: ten screws (two at the back, three on each side, two on top). Push each side clear of its chassis tab, flex the sides out and tilt the shield forward.
  5. Discharge the CRT, remove the anode cap and fit the ongoing ground.
  6. Board module: after the convergence/tilt board, unplug the 4-pin yoke cable P704 on the left, P902 (two twisted brown wires) on the right of the main deflection board, and P303 (two twisted black wires with a ferrite bead) on the CRT/video board. Apple warns that P902 and P303 have almost identical connectors and that swapping them damages the boards.[1]

Diagnostic checks

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Apple's flowchart for a suspected hardware fault checks four voltages in order. If all four are in range, the CRT is replaced and the readings taken again; if the high-voltage, heater or RGB readings are out, the main deflection and CRT/video board module is replaced.[1]

Apple's voltage checks, Studio Display (17-inch CRT)[1]
Check Where Expected
High voltage Apple high-voltage probe 076-0392 under the anode cap, inserted from the rear of the CRT away from the frame; ground wire on the chassis. Apple says other probes will not read correctly. 27 V DC ± 0.2 V on the meter, which is 27 kV
B+ Pin "180V" at P305 on the solder side of the CRT/video board (remove the four screws of the board's back plate), against chassis ground 180 V ± 2.0 V
Heater Pin H on the solder side of the CRT socket 6.3 V ± 0.63 V
RGB cathodes Pins RD, GN and BL on the solder side of the CRT socket 65-85 V each, and nearly equal

For each check Apple switches off, disconnects the power cord and video cable and waits at least two minutes before connecting the meter, then reconnects and switches on to read.[1]

The chassis maker's manual sets the same two main figures from the board side: the B+ at the positive end of C951 to 180 V ± 0.5 V with VR901, and the anode to 27 kV ± 0.2 kV with VR501, both after at least 30 minutes' warm-up on a crosshatch.[2]

Screen, geometry, convergence and focus

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  • Screen voltage: remove the rear housing and warm up for five minutes. At 1024 × 768, 75 Hz, show the grey bars in the Display Service Utility, set brightness to its detent and contrast to maximum, dim the room, and turn the Screen control (the lowest control on the flyback transformer) with a plastic screwdriver until only the leftmost bar is fully black and the second is just distinguishable. Apple calls for this when diagonal trace lines appear.[1]
  • Geometry: fit Apple's adjustment adapter (077-0168) between the computer and the display cable. Open the on-screen display, press the adapter's red button once, then choose Geometry: a music-note symbol at the lower left shows factory mode, and changes are now saved as factory settings. Adjust side pincushion balance, parallelogram, pin S, pin W, tilt and zoom, then switch the display off and on to leave factory mode.[1] The chassis maker's manual describes the same factory mode entered from the OSD itself.[2]
  • Convergence: at 832 × 624, 75 Hz, show a full white screen. If red shows at the edges, enter factory mode as above, choose Image, then Moire (Convergence), and adjust H Convergence for red at the sides and V Convergence for red at the top or bottom. If red persists, balance it with Color, Custom Color.[1]
  • Focus: with brightness and contrast at maximum and 1280 × 1024, 75 Hz, show the focus pattern of percent signs and adjust the two focus controls on the flyback for the best centre focus, alternating between them.[1]

Aperture grille lines

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The Diamondtron's aperture grille is made of very fine vertical wires, which can stick together after the display has been cold or shaken, leaving thin vertical lines. Apple's remedy, after taking off jewellery: strike the side of the case under the Apple logo with the heel of the hand, first on the right and then on the left. If the lines remain, lay a soft cloth over the screen and tap the centre of the face lightly with a solid rubber mallet, increasing the force only up to a swing of about 12 inches. Replacing boards will not cure it.[1]

Capacitors

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Apple gives no component values, but the chassis maker's parts list does; the electrolytics are listed in Apple Studio Display 17 Capacitor Replacement Guide.[2]

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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 1.15 1.16 1.17 1.18 1.19 Apple Computer, Studio Display (17" CRT, 16" VIS) (Service Source), hosted as File:Studio display 17.pdf (see Studio Display (17" CRT, 16" viewable image size) Service Source). PDF page numbers: Repair Issues pp. 6-11; Take Apart: safety guidelines pp. 39-41, tools p. 44, intermediate bezel pp. 45-51, tripod stand pp. 52-56, rear housing pp. 57-59, EMI shield pp. 60-66, main deflection and CRT/video board module pp. 71-80; Adjustments: tools p. 107, safety p. 108, on-screen display pp. 109-111, diagnosing a suspected hardware problem and flowchart pp. 112-113, checking high voltage p. 114, checking B+ voltage pp. 115-116, checking heater voltage pp. 117-118, checking RGB voltages pp. 119-120, adjusting screen voltage p. 121, adjusting screen geometry pp. 122-123, checking screen colour and adjusting convergence pp. 124-125, adjusting focus p. 126.
  2. ↑ 2.0 2.1 2.2 Service manual for the display chassis (DA796; parts list headed "Model: M6496", 25 October 1998), hosted as File:Apple Studio Display 17-inch CRT Service Manual (DA796 chassis).pdf (see Apple Studio Display 17 Documentation). Adjustments (PDF pp. 10-11): warm up at least 30 minutes; B+ at C951 (+) 180 V ± 0.5 V with VR901; FBT anode 27 kV ± 0.2 kV with VR501; horizontal raster centre with SC701; factory mode by the alignment program or from the OSD by switching ST off and on (0.5-1 second), shown by a symbol at the lower left of the OSD; focus with the two focus controls on the FBT; screen control on the FBT for 0.15 ± 0.02 fL raster luminance in the factory white-balance procedure.


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