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The ultimate VGA to SCART adapter

15.7KHz composite sync generator for old arcade monitors and SCART TVs enhanced following visenri's indications

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Accurate recreation of vintage arcades is becoming increasingly difficult. CRT monitors are rare nowadays and, even if you find one, it will probably not support the 15.7Khz horizontal frequency used by many old arcades. A good alternative is a CRT TV with a SCART connector. If your system has a VGA output and you can configure it to use an horizontal frequency of 15.7Khz then you can use this adapter to connect it to the SCART input of a TV. This project is an enhanced version of my previous adapter. Visenri told me I should use a PIC16F18313 so it could generate the status signal itself. The adapter is easy to make, unexpensive and powerfull.

Warning: I have just realized that the DE-15 was hard to fit because its footprint is not OK. The current published version of the PCB (labeled 1.2) has the wrong footprint.

Update: I have uploaded a new version (labeled 1.4) with the correct footprint, but I haven't tested it yet. I will test it as soon as possible.


Disclaimer: Use the information provided here at your own risk. I do not take any responsibility for any resulting damage.

This adapter is based in the cheap PIC16F18313 microcontroller following Visenri's indications. It has the following pros:

  • It automatically detects the polarity of the input VGA sync signals and configures the configurable logic cells (CLC) of the PIC dynamically to generate the SCART composite sync signal correctly.
  • If the frequency of the VGA horizontal sync signal is wrong or if the VGA vertical sync signal does not change then the PIC disables the SCART composite sync signal, the SCART RGB selection signal and the SCART status signal.
  • Most VGA devices can provide enough power to the PIC so no external power source is required.
  • No external power source nor DC-DC converter is required to generate the 12V of the SCART status signal. It can be generated by the PIC itself as noted by Visenri.
  • Optional aspect ratio selection.
  • Optional LEDs  to test the power and input sync signals.
  • Optional power source selection.
  • The basic circuit only requires the PIC and a pair of resistors and capacitors.
  • The full circuit fits in a (big) DE-15 enclosure using a single sided PCB and easy to solder through-hole components.

Pin outs

PIN #

name description
1 RED Red video
2 GREEN Green video
3 BLUE Blue video
4 ID2/RES formerly Monitor ID bit 2, reserved since E-DDC
5 GND Horizontal sync ground
6 RED_RTN Red return
7 GREEN_RTN Green return
8 BLUE_RTN Blue return
9 KEY/PWR formerly key, now +5V DC, powers EDID EEPROM chip on some monitors
10 GND Vertical sync ground
11 ID0/RES formerly Monitor ID bit 0, reserved since E-DDC
12 ID1/SDA formerly Monitor ID bit 1, I²C data since DDC2
13 HSync Horizontal sync
14 VSync Vertical sync
15 ID3/SCL formerly Monitor ID bit 3, I²C clock since DDC2

Table 1: Pin out of a female DE-15 connector functioning as a VGA output from wikipedia


PIN #

description

1 Audio output (right)
2 Audio input (right)
3 Audio output (left/mono)
4 Audio ground
5 Blue ground
6 Audio input (left/mono)
7 Blue
8 Status & Aspect Ratio
0–2 V → off
+5–8 V → on/16:9
+9.5–12 V → on/4:3
9 Green ground
10 not used in this project
11 RGB Green
12 not used in this project
13 Red ground
14 pin 8 ground
15 Red
16 RGB selection
0–0.4 V → composite
1–3 V → RGB
17 Composite sync ground
18 pin 16 ground
19 Composite sync output
20 Composite sync input
21 Shell/Chassis

Table 2: Pin out of a SCART connector from wikipedia

... Read more »

KiCad_ultimateVGA2SCART.zip

KiCad project files

Zip Archive - 1015.14 kB - 08/30/2019 at 20:15

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ultimateVGA2SCART1_4.zip

GERBER files for the PCB

Zip Archive - 43.08 kB - 08/30/2019 at 20:13

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ayuda_corte_carcasa-job.gbrjob

GERBER file of the dummy PCB I used to help me to cut and drill the DE-15 case.

gbrjob - 851.00 bytes - 08/09/2019 at 19:53

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main.c

firmware source code

x-csrc - 7.83 kB - 08/09/2019 at 19:46

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x-hex - 1.18 kB - 08/09/2019 at 19:41

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  • 1
    Program the microcontroller

    Flash the PIC using this compiled code.

  • 2
    Get the printed circuit board

    You can order it (for example at JLCPCB or ALLPCB) or make it yourself using these GERBER files.

  • 3
    Solder the DE-15 connector

    You must solder it first because it is quite hard to fit. Also you must remove the nuts of the photo.

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Discussions

gambaman wrote 08/30/2019 at 21:44 point

I have uploaded a new version (labeled 1.4) with the correct footprint, but I haven't tested it yet. I will test it as soon as possible.

  Are you sure? yes | no

gambaman wrote 08/28/2019 at 18:24 point

I have just realized that the DE-15 was hard to fit because its footprint is not OK. The current published version of the PCB (labeled 1.2) has the wrong footprint. I will publish a fixed version as soon as possible.

  Are you sure? yes | no

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