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'''JP21''' (also known as '''RGB21''' or '''Japanese SCART''') is a 21-pin audio/video connector used primarily on Japanese consumer electronics. While physically identical to the European [[SCART]] connector, JP21 has a different pinout and is electrically incompatible.
'''JP21''' (also known as '''RGB21''', '''RGB21ピン''', or '''Japanese RGB-21''') is a 21-pin audio/video connector standardized by EIAJ (Electronic Industries Association of Japan) for use on Japanese consumer electronics. While physically identical to the European [[SCART]] connector, JP21 has a completely different pinout and is electrically incompatible.


== Pinout Differences from SCART ==
== Standards ==


The most significant differences between JP21 and SCART:
JP21 was standardized by EIAJ with the following document history:
* '''EIAJ TTC-0003''' (January 1983) - Original standard
* '''EIAJ CPR-1201''' (March 1993) - Revised to include S-Video support
* '''EIAJ CPR-1205''' (March 2003) - Final revision before withdrawal due to Japan's transition to digital


* '''Red and Blue are swapped''' - JP21 uses pin 7 for red and pin 15 for blue, opposite of SCART
The connector was adopted in Japan specifically for its ability to carry RGB signals without compression or deterioration, but unlike SCART in Europe, it never achieved universal adoption on consumer televisions.
* '''Pin 16''' - SCART uses this for blanking/RGB switching (+1-3V), while JP21 provides +5V
* '''Pin 8''' - Function select voltage differs between standards


== Compatibility ==
== Pinout ==
 
{| class="wikitable"
|+ JP21 vs SCART Pinout Comparison
! Pin !! JP21 Function !! SCART Function
|-
| 1 || Audio Input (Left) || Audio Output (Right)
|-
| 2 || Audio Output (Left) || Audio Input (Right)
|-
| 3 || Audio Input Ground || Audio Output (Left)
|-
| 4 || Audio Output Ground || Audio Ground
|-
| 5 || Audio Input (Right) || Blue Ground
|-
| 6 || Audio Output (Right) || Audio Input (Left)
|-
| 7 || Composite Video Input Ground || '''Blue Signal'''
|-
| 8 || Composite Video Output Ground || Widescreen Switching
|-
| 9 || Composite Video Input || Green Ground
|-
| 10 || Composite Video Output || Data Bus Input
|-
| 11 || AV Control Signal || '''Green Signal'''
|-
| 12 || RGB Mask Signal (Ym) || Data Bus Output
|-
| 13 || '''Red Signal Ground''' || Red/Chroma Ground
|-
| 14 || Ym/Ys Ground || Data Bus Ground
|-
| 15 || '''Red Signal''' || '''Blue Signal'''
|-
| 16 || RGB Switching Signal (Ys) || RGB/Composite Switching
|-
| 17 || '''Green Signal Ground''' || Composite Output Ground
|-
| 18 || '''Blue Signal Ground''' || Composite Input Ground
|-
| 19 || '''Green Signal''' || Composite Output
|-
| 20 || '''Blue Signal''' || Composite Input
|-
| 21 || Frame Ground (metal shell) || Frame Ground (metal shell)
|}
 
'''Key incompatibilities:'''
* Red and Blue signals are swapped (pins 7/15/20 vs 15/7/20)
* RGB signal pins vs ground pins are arranged differently
* Control signal voltages and functions differ
 
== Technical Specifications ==
 
{| class="wikitable"
! Signal !! Specification
|-
| Composite Video || 0.7Vp-p, 75Ω impedance
|-
| RGB Signals || Positive analog, 0.7Vp-p, 75Ω impedance
|-
| Audio || 0.4Vrms, Input: 47kΩ, Output: 10kΩ
|-
| Ys (RGB Switching) || Low: 0-0.4VDC (Composite), High: 1.0-3.0VDC (RGB), 75Ω
|-
| Ym (Masking) || High level masks composite video, same levels as Ys
|-
| AV Control || TTL level, 22kΩ impedance
|}
 
The connector carries 15.75kHz composite sync (C-SYNC), the same as standard analog television. This limits the maximum resolution to 240p/480i and makes JP21 incompatible with VGA monitors that expect separate H-SYNC and V-SYNC signals.
 
== Compatibility with SCART ==


Connecting SCART equipment directly to JP21 will result in:
Connecting SCART equipment directly to JP21 will result in:
* Red and blue color channels being reversed
* Red and blue color channels being reversed
* Possible RGB switching issues due to voltage differences
* RGB switching failures due to voltage/pin differences
* Possible audio issues


Adapters or custom-wired cables are required to connect European SCART sources to Japanese JP21 displays (or vice versa). These typically cross the R and B lines and may include voltage regulation for the blanking signal.
'''To adapt SCART sources to JP21 displays:'''
* Swap the Red and Blue signal wires
* Add 100-220μF polarized capacitors on each RGB line
* Add a 100Ω resistor between SCART pin 16 and JP21 pin 8


== Common Equipment ==
'''To adapt JP21 sources to SCART displays:'''
* Swap the Red and Blue signal wires
* May need voltage adjustment for blanking signal


JP21 connectors are found on:
== Compatible Equipment ==
* Sony Profeel series monitors ([[Sony KX-21HV1]], [[Sony KX-27HV1]], etc.)
 
* Japanese consumer televisions with RGB input
=== Monitors and Televisions ===
* MSX computers and peripherals
* Sony Profeel Pro series ([[Sony KX-21HV1]], [[Sony KX-27HV1]], KX-27HV2, KX-34HV2)
* Various Japanese game consoles and accessories
* Sony GVM-14/21 series monitors
* Japanese professional monitors
* NEC PC-TV series
* Sharp CZ-600 series monitors
* Various Japanese consumer televisions with RGB input
 
=== Game Consoles with Native JP21 Support ===
* '''Super Famicom''' - via SHVC-010 cable
* '''PlayStation''' / PS one / PlayStation 2 / PlayStation 3 - via SCPH-1050 cable
* '''Sega Saturn''' - via HSS-0109 cable
* '''Neo Geo''' / Neo Geo CD - via FCG-9 cable
* '''Super Cassette Vision''' - via dedicated RGB cable
* '''Dreamcast''' - third-party cables (some software incompatible)
* '''Xbox''' - third-party cables available
 
=== Game Consoles Requiring Modification ===
* '''Famicom''' - requires internal PPU modification
* '''Nintendo 64''' - requires internal modification with DAC
* '''GameCube''' - requires component cable modification
* '''Sega Mark III''' - weak output, requires amplifier
* '''Master System''' - only Sega custom chip versions support RGB
* '''Mega Drive''' - requires cable with termination resistors
* '''PC Engine''' - requires expansion bus or internal modification
 
=== Computers ===
* MSX2 and later models (Sony, Panasonic, Yamaha, Sanyo, etc.)
* PC-8801mkIISR series
* PC-9801 series (some models)
* FM77AV series
* SMC-777
 
=== Other Equipment ===
* Arcade game control boxes (JAMMA to JP21 adapters)
* Various Japanese video equipment


== See Also ==
== See Also ==


* [[SCART]] - European 21-pin connector with different pinout
* [[SCART]] - European 21-pin connector with different pinout
== References ==
* [https://ja.wikipedia.org/wiki/RGB21%E3%83%94%E3%83%B3 RGB21ピン] - Japanese Wikipedia
* [https://www.msx.org/wiki/RGB21_connector RGB21 connector] - MSX Wiki


[[Category:Connector types]]
[[Category:Connector types]]
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