Apple Composite Monitor General Maintenance

AppleColor Composite Monitor IIe (Ben Boldt, Wikimedia Commons, public domain)

Safety, fuses, board changes and Apple's adjustment procedures for the AppleColor Composite Monitor and the ColorMonitor IIe and IIc. Apple's procedures differ between the two internal designs, Series "S" and Series "H"; identify yours first.

Identify the series

Look at the hinges of the control door under the screen. Two plastic hinges with metal pins: Series "S". Three all-plastic hinges that bend along a crease: Series "H". A platinum AppleColor Composite Monitor IIc is always Series "S" and a platinum AppleColor Composite Monitor IIe always Series "H". Inside a Series "H", a separate power supply board means the Rev. A logic board; no separate power supply board means Rev. B.

Live chassis on Series "H" Rev. B

The Series "H" Rev. B monitor has no isolation transformer and its chassis is connected to the mains neutral. If the plug or the outlet is wired the wrong way round, the chassis carries a lethal current.

Apple's rules for this monitor: use only a properly earthed three-pin outlet installed by an electrician, never an adapter plug, and put an isolation transformer between the monitor and the outlet for any work with the cover off. Apple lists the isolation transformer among the materials for Series "H" Rev. B colour adjustment.

The CRT itself needs discharging before you touch anything inside; see CRT Discharge Procedure. Apple's take-apart sections discharge it with the tool 076-0381 and keep an earth lead on the anode while working.

Opening the case

Switch off, unplug the mains lead and video cable, and lay the monitor face down on a soft surface. On a Series "S" IIc monitor, remove the four screws on the back and lift the rear cover until it clears the CRT board on the end of the tube neck. The cover cannot come fully away until the power switch cable is unplugged from the power supply board. The IIe cases and the Series "H" monitors have their own rear cover procedures in the same manual.

Fuses

Mains fuses

Series	Fuse	Value	Apple part
"S"	F871, on the component side of the power supply board	3 A 250 V slow-blow, 3AG	740-0102
"H"	F901, on the logic board	4 A 125 V medium time-lag (replaces the original 3.15 A 250 V)	740-0401
"H"	F902, on the logic board	1 A fast-blow	740-0304

Lift a fuse out by prying up one end with a finger or small screwdriver. Do not slide it sideways in the holder; that can break the holder.

Series "H" fuse upgrade

The original 3.15 A 250 V fuse at F901 showed a one per cent failure rate in Apple's testing. Apple ordered every 3.15 A fuse at F901 replaced with a 4 A 125 V fuse when it fails or whenever the monitor comes in with any fault, for example when the CRT is replaced. Apple's kit added a small label under the fuse holder and two labels (English and French) inside the rear cover. With the monitor face down, remove the two screws of the bottom panel of the logic board, black out the old fuse marking on the board with a felt pen, and refit the panel with its four metal teeth aligned before tightening the screws.

LED after a board change

On a Series "H" IIe monitor, the Rev. B logic board reverses the polarity of the LED circuit. If the power light is dead after a board swap, unplug the LED connector (from the logic board on Rev. B, or from the small vertical video board on Rev. A), press in the two small holes on each side with a screwdriver tip to release the lead tabs, straighten the tabs' teeth, swap the two leads, and push them back until they click.

Adjustments

Apple's rules: do not touch the yoke; check text and colour with a program after any module change; and do not change the internal colour settings if colour is acceptable, because a perfect set-up needs special equipment. Apple's test patterns come from the Apple II Peripherals Diskette (dot pattern, 40-column text, colour bars, grid and others).

Text (both series)

All text controls are external. Open the door under the screen, set brightness for the room, then set contrast for a good balance between characters and background. Colour intensity, tint and WHITE ONLY have no effect on text. Use the rear vertical hold if the picture rolls.

Colour, Series "S"

Warm up for 15 minutes with the rear cover off and a mirror in front of the screen. Set colour intensity fully anticlockwise, brightness to its click, contrast fully clockwise, and press WHITE ONLY in. The internal controls (red and blue drive, red, green and blue bias, sub-brightness) are behind the power supply board, which carries very high voltages; use an insulated tool. Set them to mechanical centre, then turn the service switch SW800 so its lever points towards the tube at 45 degrees: the screen collapses to one horizontal line. Turn the bias control of any colour that shows in the line slightly anticlockwise until the line is neutral white, then put SW800 back (lever towards the back of the monitor) and WHITE ONLY out. Finish with colour intensity and contrast for the best picture and tint so that the yellow bar is at its yellowest.

Colour, Series "H"

Read Apple's isolation transformer warning first. Warm up for 15 minutes, display the colour bars, set contrast fully clockwise and brightness for best viewing, then display the full white screen. The internal controls are on the CRT socket board; Series "H" has no service switch. Set B-DRIVE to half, R-DRIVE to three quarters, B-BKG to half, G-BKG to a quarter and R-BKG to half of their travel, measured from mechanical centre. Turn B-DRIVE clockwise until the raster turns bluish, set R-BKG to a quarter and bring it up until the raster just turns reddish, then adjust B-BKG and G-BKG alternately for a greyish white. Return WHITE ONLY to out, set colour intensity, set tint for the yellowest yellow bar, set brightness so the background behind the bars is black and finish with contrast. Repeat from the colour bars if the result is not acceptable.

Related pages

• Apple Composite Monitor
• Apple Composite Monitor Troubleshooting Guide
• Apple Composite Monitor Documentation
• Capacitor Failure Symptoms