Safely discharging CRT monitors

IMPORTANT: CRT MONITORS CAN HOLD ANYWHERE BETWEEN 15K VOLTS (small B&W)-25k VOLTS (small-medium color), UP TO 50K (TVs, studio monitors, high-end desktop monitors like the GDM-FW900). DUE TO THE WIDE VARIATIONS OF WHAT EACH TYPE CAN HOLD, IT IS CRITICAL THAT THESE GET DISCHARGED CORRECTLY!

This Wiki aims to bridge the information from this 2018 answer and expand on the topic further, making the format better suited for use in the field. This post was made as the age of the answer, most of this information is aging to a point where it is becoming hard to locate: Disassembling an old Apple monitor. In addition to this answer and post, refer to this Apple documents: CRT Safety Apple CRT Safety (Classic Macs)

The first rule for safely discharging a CRT monitor is to ensure the monitor or computer is unplugged to prevent further charge from being restored. In addition, IF possible, flip the power switch on for 30 seconds, up to 1 minute (or hold the power button) to discharge the monitor. On modern "bleeder-based" CRTs, this is usually enough to discharge it, but beware: These resistors are typically burned out or abused to the point they are ineffective or weak! It is a silent process that pushes the resistor harder than other applications, so they only last a few years before weakening or failing. It is also a "silent" discharge (except for static sounds on some, but do not rely on this) and will not provide a visual indication. Due to these factors, a manual discharge is still required.

Larger CRTs (typically 27"+ and professional monitors) can exhibit a “rebound” charge after initial discharge. For safety, wait 1–2 minutes and discharge again to ensure full energy release.

Key takeaway: DUE TO THE ABUSE THESE RESISTORS TOOK WHEN THE CRT DISPLAY WAS NEW OVER THE COURSE OF TIME WHEN THE CRT DISPLAY WAS YOUNG, ASSUME THEY ARE BURNED OUT WITH THE AGE OF THESE MONITORS TODAY!

IMPORTANT: DO NOT WEAR ANY GROUNDING STRAPS; ELECTRICITY CHOOSES THE PATH OF LEAST RESISTANCE, AND YOUR ESD PROTECTION WILL BECOME THE GROUND. As such, you must remove all jewelry (and items like necklaces or chokers with a metal clasp; yes, that clasp is enough to cause harm) to mitigate the risks associated with jewelry completely.

After making sure you do not become the new "ground," it is time to discharge the CRT. You can do this with an official discharge tool (these were designed for companies like Apple for service purposes) or an open-market tool, which was available and sold to the public (or at least, only to third-party repair shops).

NOTE: These tools are no longer in production and are extremely rare (if not unobtainable today). As such, we now need to improvise; you can use a plastic-handled screwdriver with a rubber grip as a discharge tool. However, a rubber coated handle is strongly recommended (and use of such a screwdriver is encouraged). The risk of injury or death greatly outweighs the slight markup to have a rubber insulated handle as an additional safety layer.

These are not hard to find and can readily be found in hardware stores such as Home Depot or Lowes. These can sometimes cost significantly more than a plastic handle driver but are properly insulated.

If possible, it is also advisable to insulate part of the screwdriver handle with heat-shrink tubing, as this provides an additional cushion in case you accidentally touch the metal on the screwdriver. Caution is still required. Refer to this guide for a visual aid on the discharge process: Macintosh Classic II Power Board Removal. If you can locate the tool, this is generally what they look like (this tool is an example of the Apple-made version before they stopped working on CRT-based Macs). However, other versions were also made by different companies that serve the same purpose:

IMPORTANT: WHEN DISCHARGING THE CRT ITSELF, DO NOT HAVE BOTH HANDS IN THE WORKSPACE! IF BOTH HANDS ARE IN THE SPACE, THIS CAN CREATE A DIRECT SHOCK TO YOUR HEART, WHICH CAN KILL YOU. Place your nondominant hand behind your back or in a pocket to make sure you do not create a complete circuit and use your preferred dominant hand.

Key takeaway: It is better to drop a loud F-bomb your neighbor can hear with one hand in your pocket instead of being dead... Once you hear the CRT make a "crack" sound, the CRT has been discharged.

If you are working on the CRT and replacing a component like the flyback transformer, you must create an ongoing ground with the CRT itself until the repair (like the flyback transformer) is completed and the old one is removed from the CRT HVPS. Refer to these screenshots to see how to do this:

If you have followed these safety rules to a T, you have successfully discharged a CRT and did not injure or shock yourself while discharging your CRT display.