CRT:Frequently Asked Questions (FAQ)

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Frequently Asked Questions (FAQ)

What is a CRT?

CRT example.png

A Cathode Ray Tube display, characterised by its large vacuum tube. At the back is an electron gun which fires towards phosphors in the front, lighting them in a variety of colors. The gun re-angles while painting each image line by line, and the phospors fade before being redrawn anew.

The number of complete display updates completed per second is measured in hertz ("cycles"). 50hz or 60hz are common refresh rates for older televisions, although some sets can be made to update much faster. Use of a light gun accessory often requires a CRT: such devices, contrary to their names, actually contain cameras which track the progress of a CRT's refresh. By timing how long it takes for an electron gun to reach the region of the screen where they're pointed at, they can determine where that region actually is and hence what a player is shooting at. Flat panel displays (which remain fully lit at all times) are incompatible with this technique, forcing console developers to come up with other techniques - for eg, the Nintendo Wii appeared as CRTs started to fall out of fashion, and so included its own light sensor bar (a simple row of five infrared LEDs, tracked by a camera in the Wiimote hand controller).

CRTs don't have "pixels" as such: altering the number of rows they can display is a simple matter of controlling the angle the electron gun fires along. If too many rows are specified, the gun may not be able to move fast enough to maintain the target refresh rate, creating a flickering effect: interlacing is commonly used to alleviate this problem.

Most sets include either a dial or menu function for the purpose of recalibration, allowing any given image to be stretched / reduced to fit correctly. This is in contrast to flat panel displays, which have a specific number of pixels built into them which cannot be physically resized. Failure to use anything other than a flat panel's "native" resolution may result in color dots being spread unevenly across multiple pixels, producing unnatural shapes. This is especially an issue when dealing with older consoles that tend to output lower display resolutions.

What is 240p?

See the "What is 240p?" page.

What are the meaning and implications of this "frequency" spec?

See the "Hz" page.

What is the default password for a Sony BVM's menus?

Try 1111, 9999, and 53415 ("SEALS"). Beyond that, start with guessing common sequences like 1234 or 9876 and other repeated digits like 2222 that someone may have set it to.

How can I check the hours on my monitor?

For Sony monitors, only Sony BVM and HDMs track hours. You can view the hours by going to Menu > Status. Some monitors will only list "Operation Time" — which is the time that the monitor has been on or in standby mode — and some monitors will also list "CRT Turn On Time" which is solely the amount of hours that an image has been on the tube (not in standby mode). Older BVMs will display their operation time count under the "Monitor Type" menu as an unlabelled number beneath the version number.

What is Y(B-Y)(R-Y)?

Y(B-Y)(R-Y) is YPbPr. Earlier monitors use the (B-Y)(R-Y) notation instead of PbPr.

What is YCbCr?

Strictly yet overly simply speaking, YCbCr is a family of digital "luma and color differences" encodings, a small yet fundamental building block of most lossy photo and video codecs (and of the GameCube's digital video port).

However, with regards to analog video gear and connectors, it can be treated as a misspelling of YPbPr.

Which consoles can output RGB / Component?

See the Console Video Output page.

How can I adapt my cables to (or from) SCART / BNC / RCA?

See the Video Cables page.

Which CRTs can be modified to accept RGB?

See the RGB Modification page.

What's the difference between RGB / RGBS / RGBHV / RGBcvS / SoG / YPbPr?

See the Types of Sync page.

What is the difference between different Professional / Broadcast video monitors?

See the definitions of PVM and BVM below and the models list for specifics.

Where can I get my CRT serviced?

See the list of CRT Service Technicians.

How can I learn more technical information about CRTs?

See this guide which covers almost anything you could ask about CRTs.

What are some good video switchers?

Main article: AV:Audio_Video_Wiki

Except for use as an extension cord, avoid any multi-socket device that does not in fact switch, since the additional terminating resistors in the unused equipment (or the branching "tentacles" if only the cables are left connected) will degrade the signal, often visibly, due to impedance changes and reflections.



  • Extron Crosspoint
    • 84 Series: 8 input x 4 output matrix
    • 88 Series: 8 input x 8 output matrix
    • 124 Series: 12 input x 4 output matrix
    • 128 Series: 12 input x 8 output matrix
    • 168 Series: 16 input x 8 output matrix
    • 1616 Series: 16 input x 16 output matrix
    • 2412 Series: 24 input x 12 output matrix
    • 2424 Series: 24 input x 24 output matrix
    • 3216 Series: 32 input x 16 output matrix
    • 3232 Series: 32 input x 32 output matrix
      • HVA models indicate audio support via Pheonix connectors
      • ADSP models regenerate a new sync signal on H/V
      • Takes both TTL and non-TTL sync input, only outputs TTL sync
  • Otaku Switch (6 input)



Term Definition
TV Lines (TVL) The maximum number of alternating light and dark vertical lines that can be resolved per picture height. Limiting factors include the driving circuitry, the number of phosphors on the tube, and the number of slots in the slot mask or aperture grille.
Flyback (need a good definition)
Deflection (need a good definition)
Pots Potentiometers are components that can be adjusted to affect things like deflection, color balance, and voltage levels. Twistable knobs are just potentiometers that are accessible.
Convergence Proper convergence means that the red, green, and blue spots generated by the three color CRTs inside your set are hitting the same point and therefore are creating the proper color.
Input Board Input boards, or input cards, are modular cards that can be added or removed from professional CRTs. With Sony CRTs, only BVMs have input boards.
Phosphors The patches of chemicals on the inside of the glass that lights up when the electron gun beam hits it. There are different phosphor formulations that fit standards such as SMPTE-C, EBU, P22, and EIA. They play a part in color accuracy and some phosphors output light for a longer period of time than others leading to a trailing or ghosting effect when a bright object is moved across a dark area, such as a cursor across a black background.
Pincushion (needs a definition)
VTR Video Tape Recorder. Many sets have a VTR port on the back which can carry audio and composite video.
ISR Interactive Status Reporting. A Sony proprietary system in which you can get diagnostic information from your Sony devices using a serial cable and the BZI-500 (or BZI-501) software on a Windows 95 / NT4 based PC.
BVM Broadcast Video Monitor. Sony models starting with "BVM-". Originally used for monitoring the master signal at broadcast studios when live on air to ensure perfect quality. These sets generally use the same tubes as equivalent PVMs, but have removeable input boards.
PVM Professional Video Monitor. Sometimes used generically to mean any professional monitor, but usually used to refer to Sony models starting with "PVM-". Originally used for professional image and video editing.

Sync signals

Term Definition
RGsB Sync on Green (SoG). RGB using 3 wires: Red, Green + Sync, and Blue. Very rare Sync on Blue (RGBs) variant exists.
RGBS (Composite Sync) RGB with Composite Sync (CSYNC). RGB using 4 wires: Red, Green, Blue, and Sync (horizontal and vertical sync combined).
RGBcvS (Sync on Composite) RGB using 4 wires: Red, Green, Blue, and Composite Video (composite video Sync). More commonly just called RGBS, as composite video includes sync by definition, and is often but not always interchangeable with strict RGBS. With added audio and transparency/"fast blanking", standard signal for SCART and JP-21.
RGBYs (Sync on Luma) RGB with Luma as the sync signal. Often just called RGBS, as luma is by definition composite video without encoded color.
RGBHV Independent/Separate sync. RGB using 5 wires: Red, Green, Blue, Horizontal Sync, and Vertical Sync. This is generally what PCs output on VGA ports.

Video signals

Term Definition
TTL Transistor-Transistor Logic - conventional name for a 0/5 V digital signal, as seen in most digital RGB schemes (as listed hereafter) but also in monochrome MDA/Hercules and some nonstandard industrial monitors.
RGBI A 4-bit per pixel, 16-color digital RGB system most commonly used for CGA. It can display any combination of primary colors (black, R/G/B, C/M/Y, white) in both dark/regular and bright versions. Many but not all RGBI monitors, however, convert dark yellow to brown. Sync type is not specified by the term but generally assumed to be separate (HV).
XRGB An obscure 4-bit per pixel, 16-color digital RGB system most commonly used on the Apple III providing an unique color palette. Sync type is not specified but generally assumed to be composite (S).
RGBrgb A 6-bit per pixel, 64-color digital RGB system most commonly used for EGA. Sync type is not specified but generally assumed to be separate (HV).

Sony Model Definitions

See this page for a list of Sony prefixes definitions (PVM-, CPD-, BKM-).