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Additional monitor technology and repair information

Why are there fine lines across my Trinitron monitor or TV?

Safe discharging of capacitors in TVs and video monitors

Specific considerations before poking around inside a TV or monitor

Troubleshooting a monitor with the mainboard disconnected

Optimal procedure for setting brightness/background and screen adjustments

Why is the convergence on my monitor bad near the edges

Monochrome monitor size, position, and geometry adjustments

What symptoms are likely the result of a low voltage power supply problem?

Internal fuse blew during lightning storm (or elephant hit power pole)

Fuse replaced (doesn’t blow) but monitor is still nearly dead

Power-on tick-tick-tick or click-click-click but no other action

Dead monitor with audible whine, periodic tweet or flub, and low-low voltage

Startup problems – nothing happens, click, or tick-tick-tick sound

Monitor shuts down with bright picture or when brightness is turned up

Gross problems in size or position at certain scan rates

Picture squeezed on both left and right side of screen

Loss of horizontal sync (also applies to vertical) after warmup

Bright or dark bars on edge of picture (horizontal or vertical)

Intermittent jumping or jittering of picture or other random behavior

Horizontal output transistors keep blowing (or excessively hot)

Horizontal output transistors blowing at random intervals

Uncorrectable pincushion distortion with new monitor

High voltage shutdown due to X-ray protection circuits

Excessive low voltage supply may trigger high voltage shutdown

Arcing, sparking, or corona from CRT HV anode (red wire/suction cup)

Arcing at spark gaps and gas discharge tubes on CRT neck board or elsewhere

Spark gaps and gas discharge bulbs on CRT neck board or elsewhere

Dave’s complete procedure for repair of an arcing flyback

Arcing due to bad connections to or disconnected CRT return

Erratic focus or screen (G2) voltage and/or controls on flyback

Disconnecting flyback wire(s) from CRT driver board

Focus or screen voltage drifts after warmup only when CRT is connected

Blank picture, power light on, digital controls (if any) active

Monitor manufacturing quality and cold solder joints

Why can’t monitor manufacturers learn to solder properly?

Ghosts, shadows, or streaks in picture adjacent to vertical edges

General streaks or lines to the right of bright or dark areas

Color balance changes across screen from left to right

Why does the intensity appear so non-uniform in bright areas?

Brightness changes from left-to-right across screen

Occasional static, lines, spots, or other unsightly blemishes

Magnet fix for purity problems – if duct tape works, use it!

Jittering or flickering due to problems with AC power

Sources of external interference that can affect the monitor display

Cable installed upside-down – now monitor does not sync correctly

Monitor shuts down or goes blank at certain scan rates

High pitched whine or squeal from monitor with no other symptoms

Should I replace all the electrolytic capacitors if I find a bad one?

Disposing of dead monitors (CRTs and charged HV capacitors)

Apple/Sony monitor dies after variable length of time

How do multiscan monitors determine and store the scan parameters?

Is fluorescent lighting a significant source of flicker?

Digital versus analog controls on monitors and picture quality

What is monitor video bandwidth and why is it important?

What is this goop around some electrolytic capacitors and other components?

Tony’s notes on setting convergence on older delta gun CRTs

Jerry’s comments on convergence and other advanced CRT adjustments

GFCI tripping with monitor (or other high tech equipment)

How do monitors know when to enter power saving modes?

Methods to prevent screen burn-in on fixed format monitors

Why are prices of video monitors so high compared to similarly sized TVs?

Why is the resolution of a computer monitor so much better than a TV

Problems with designing a combination TV and computer monitor

Identifying connections on unknown or cut monitor cables

How can I determine monitor specifications or whether it supports SVGA?

Displaying a video signal as a picture on an oscilloscope

Could a monitor be modified for 3D (stereo) display?

Should I use a VGA to BNC cable if my monitor has BNC connectors?

Tweaking the deflection rate of a fixed frequency or non-standard monitor

Modifying a CGA (or EGA) monitor for NTSC or PAL input

Picture instability of computer monitor used to watch videos

Driving multiple non-daisy-chained monitors from one video source

What is Kell factor with respect to interlaced displays?

Shipping damage 1: why monitors are like basketballs

Shipping damage 2: why monitors are like hammers (as in throw)

Shipping damage 3: why small monitors are like footballs

Shipping damage 4: so maybe if monitors were packed and shipped like eggs

Reliability and performance of refurbished or remanufactured monitors

Lament of the lack of adjustment pots on the newest monitors

We will not be responsible for damage to equipment, your ego, county wide power outages, spontaneously generated mini (or larger) black holes, planetary disruptions, or personal injury or worse that may result from the use of this material.

The earliest personal computers didn’t come with a display – you connected them to the family TV. You and your kids shared the single TV and the Flintstones often won out. The Commodore 64 would never have been as successful as it was if an expensive monitor were required rather than an option.

However, as computer performance improved, it quickly became clear that a dedicated display was essential. Even for simple text, a TV can only display 40 characters across the screen with any degree of clarity.

When the IBM PC was introduced, it came with a nice 80×25 green monochrome text display. It was bright, crisp, and stable. Mono graphics (MGA or MDA) was added at 720×350, CGA at a range of resolutions from 160×200 to 640×200 at 2 to 16 colors, and EGA extended this up to a spectacular resolution of 640×350. This was really fine until the introduction of Windows (well, at least once Windows stayed up long enough for you to care).

All of these displays used digital video – TTL signals which coded for a specific discrete number of possible colors and intensities. Both the video adapter and the monitor were limited to 2, 4, 16, or a whopping 64 colors depending on the graphics standard. The video signals were logic bits – 0s and 1s.

Note that analog video was only new to the PC world. TVs and other video equipment, workstations, and image analysis systems had utilized analog signals for many years prior to the PC’s ‘discovery’ of this approach. In all fairness, both the display adapter and monitor are more expensive so it is not surprising that early PCs did not use analog video.

Most of the information in this document applies to color computer video monitors and TV studio monitors as well as the display portions of television sets. Black and white, gray scale, and monochrome monitors use a subset of the circuitry (and generally at lower power levels) in color monitors so much of it applies to these as well.

For most descriptions of symptoms, testing, diagnosis, and repair, an auto-scan PC SVGA monitor is assumed. For a fixed frequency workstation monitor, studio video monitor, or closed circuit TV monitor, only a subset of the possible faults and procedures will apply.

Monitors designed for PCs, workstations, and studio video have many characteristics in common. Modern computer monitors share many similarities with TVs but the auto-scan and high scan rate deflection circuitry and more sophisticated power supplies complicates their servicing.

Buying a broken LCD monitor to repair may have better odds than the State Lottery, but probably not by much. Where one or more columns or rows or an entire half screen are not displaying properly, I wouldn’t consider it unless nearly totally free, hoping for a miracle, and even then it might not be worth it. Loose connectors and solder joints are possible, though not nearly as common as with CRT monitors.

Nonetheless, a variety of technologies are currently competing for use in the flat panel displays of the future. Among these are advanced LCD, plasma discharge, and field emission displays. Only time will tell which, if any survives to become **the** picture-on-the-wall or notepad display – at reasonable cost.

Since monitors with digital signal inputs are almost extinct today except for specialized applications, it is usually safe to assume that ‘digital’ monitor refers to the user interface and microprocessor control. And, except perhaps for the very cheapest monitors, all now have digital controls.

Whether the image is usable at the higher resolution of course depends on many other factors (in addition to flicker) including the dot pitch of the CRT and video bandwidth of the video card and monitor video amplifiers, as well as cable quality and termination.

Typical television CRTs are rather coarse – .75 mm might be a reasonable specification for a 20 inch set. High resolution computer monitors may have dot pitches as small as .22 mm for a similar size screen.

A rough indication of the maximum possible resolution of the CRT can be found by determining how many complete phosphor dot groups can fit across the visible part of the screen.

Running at too high a resolution for a given CRT may result in Moire – an interference pattern that will manifest itself as contour lines in smooth bright areas of the picture. However, many factors influence to what extent this may be a problem. See the section: Contour lines on high resolution monitors – Moire.

Note: The intent of these tests is **not** to evaluate or calibrate a monitor for photometric accuracy. Rather they are for functional testing of the monitor’s performance.

Obviously, the ideal situation is to be able to perform these sorts of tests before purchase. With a small customer oriented store, this may be possible. However, the best that can be done when ordering by mail is to examine a similar model in a store for gross characteristics and then do a thorough test when your monitor arrives. The following should be evaluated: