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Amiga computer related discussion => General chat about Amiga topics => Topic started by: orange on June 05, 2006, 07:34:31 PM

Title: using A520 on Speccy
Post by: orange on June 05, 2006, 07:34:31 PM

Would it be possible to connect Amiga RF Modulator to, say, ZX Spectrum +3 RGB output in order to get colour composite video output (that +3 lacks)?

Title: Re: using A520 on Speccy
Post by: whiteb on June 05, 2006, 09:27:06 PM

Spectrum +3. http://www.worldofspectrum.org/faq/reference/pinouts.htm

RGB              Pin  Signal              Level
                         -------------------------------------------------
1                        +12V
2    GND                 0V
3    Audio Out
4   /Composite Sync     TTL
5                        +12V
6    Green               Analogue 1.67V p-p
7    Red                 Analogue 1.67V p-p
8    Blue                Analogue 1.67V p-p


Amiga Video port.

1    /XCLK    IN    Extern Clock
2    /XCLKEN    IN    Extern Clock Enable (47 Ohm)
3    RED    OUT    Analog Red (75 Ohm)
4    GREEN    OUT    Analog Green (75 Ohm)
5    BLUE    OUT    Analog Blue (75 Ohm)
6    DI    OUT    Digital Intensity (47 Ohm)
7    DR    OUT    Digital Red (47 Ohm)
8    DG    OUT    Digital Green (47 Ohm)
9    DB    OUT    Digital Blue (47 Ohm)
10    /CSYNC    OUT    Composite Sync (47 Ohm)
11    /HSYNC    OUT    Horizontal Sync (47 Ohm)
12    /VSYNC    OUT    Vertical Sync (47 Ohm)
13    GNDRTN    ------    Digital Ground (for /XCLKEN) Don't connect with pin 16-20.
14    /PIXELSW    OUT    Genlock overlay (47 Ohm)
15    /C1    OUT    Clock out (47 Ohm)
16    GND    ------    Video Ground
17    GND    ------    Video Ground
18    GND    ------    Video Ground
19    GND    ------    Video Ground
20    GND    ------    Video Ground
21    -12V    OUT    -12 Volts DC (10 mA max) (A500/A600/A1200)
     -5V    OUT    -5 Volts DC (10 mA max) (A1000/A2000/A3000/A4000)
22    +12V    OUT    +12 Volts DC (100 mA max)
23    +5V    OUT    +5 Volts DC (100 mA max)

Title: Re: using A520 on Speccy
Post by: InTheSand on June 06, 2006, 12:25:24 AM

Hi,

On pre-Amstrad Spectrums, you can find a composite video signal on the Spectrum's motherboard - from the video circuitry before it hits the in-built RF modulator.

Sinclair introduced a composite signal as a separate pin on the RGB monitor output DIN socket for the original ZX Spectrum 128, which Amstrad then carried over to the original (grey) +2.

However, during Amstrad's final redesign of the +2A, +2B and +3, it seems the composite signal was removed from the monitor connector...

So you're back to having to take the signal directly off the motherboard.

You can find some info here (under the "Monitor Conversion" heading):
http://www.users.globalnet.co.uk/~jg27paw4/yr04/yr04_17.htm

and a snippet here:
http://www.nvg.ntnu.no/sinclair/faq/pinouts.html

Have fun, may your tapes load without errors!

 - Ali