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ScartCable

harbaum edited this page Sep 7, 2018 · 15 revisions

Scart Cable

The MIST can be connected to a SCART TV via a VGA to SCART cable. This must be supported by the running core and the core must generate a TV compliant RGB signal with the appropriate composite sync signal in order to allow the TV to correctly pick up the signal. The video signal must be a 15kHz/50Hz PAL signal.

Core support

The generation of a SCART TV (15khz) compliant signal is typically enabled by the following line in the MIST.INI (see the INI file documentation):

scandoubler_disable=1

The scandoubler is the component inside the Core that converts the standard TV signal the original machines generated into a VGA compliant signal. Disabling this component makes cores supporting this to output a signal similar to the one delivered by the original machine.

Supported cores

Cores know to support this option are:

  • Atari ST
  • Amiga AGA
  • C64
  • ZX Spectrum
  • VIC-20
  • ... and others ...

Some cores come with their own method of enabling 15khz/TV support. This is e.g. true for the PC-Engine and MSX cores which allow to enable TV mode via an OSD option (so you need to connect a VGA screen first to be able to use the OSD and change mode). Or simply by using a certain core version as the Atari XL and Atari 5200 cores do.

Please refer to the core documentation for details (see the links on the right).

The cable

Matching cables can be bought e.g. from Lotharek or from AMedia Computer.

SCART TVs expect at least five signals: The three analogue colour signals, a composite sync signal and a signal telling the TV to switch into RGB mode. The colour signals are directly taken from the VGA connector and have a similar function as in VGA mode. The composite sync signal (a combination of the H- and VSYNC signals) required by SCART TVs has to be delivered via the VGA connectors HSYNC pin and the RGB switch signal (permanent high) is being taken from the VGA connectors VSYNC signal.

The cable being used for this on the MIST is the same one that was used on the original Minimig. Any "Minimig SCART" cable will thus work.

Audio

The MIST provides analogue audio signals on the 3.5mm audio plug. These signals can optionally also be connected to the SCART connector on a TV.

Ground connections

There are various ground connections on the VGA as well as the SCART connector. Some of them are usually being used to shield the colour signals as well as he audio signals. At least the connection between VGA pin 10 and SCART pin 18 is required. But it is recommended to connect the shield connections as well to protect the analogue signals from noise.

Diagram

PDF

Converting similar cables

Various similar SCART-to-VGA cables can be found on auction and shopping sites using the "SCART VGA cable" search phrase. Most of these cables are configured to allow to connect equipment like DVD players with SCART output to devices with VGA input (e.g. projectors). These cables are not compatible with the MIST SCART use case since SCART uses separate pins for input and output and a SCART-to-VGA cable differs in direction from a VGA-to-SCART cable. Also the usage of the composite sync and RGB detect signals differ.

Fortunately these cables can be fixed. SCART connectors can usually easily be opened. The pins inside the SCART connector can then carefully be extracted using a pair of telephone pliers and then be reinserted to form the required cable. Unfortunately there are usually no audio connections prepared in these cables.

Links

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