RGB to SVIDEO with A-22 Converter

[crazyegg]

Hi All,

I recently bought this A-22 RGB-SVIDEO converter board from www.arcademvs.com in Canada. The price is pretty affordable at about $25 Canadian.

I was originally planning on using this board with my Commodore 128 in C128 mode with 80 column in 16 colours (using the intensity hack to get the full 16 colours)

However, I am having second thoughts, since I use my Amigas more often.

Is it possible to mod this adapter so as to work with my A1200 or A600? If so, can you post the schematics?

FYI, the A-22 board has the following connections: R-G-B-VSync-HSync-Ground.

Regards,
ed...

[ajacocks]

I'm also interested in this, for similar purposes. However, I'd attach my Apple IIgs, and my Commodore 128.

The IIgs is easy, as it has R, G, B, and composite sync. The C128 isn't _too_ hard, but the wiring of the intensity circuit would be a small challenge.

I use Indivision scan converters in my A1200, and my A3000, so I don't need the RGB adapter on the Amiga side.

[Zetr0]

@crazyegg

The A-22 Converter is for TV's not Monitors

although this should be fine for the A600 - the signals you need are on the back RGB video port.

http://pinouts.ru/Video/AmigaVideo_pinout.shtml (use the analogue colour signals not the digital)

it wont give you any benefit


so please be cautious when buying.

[Zetr0]

Just having a quick lookin on eBay.ca

and I think I have found something that might be of interest -

External CRT VGA PC TV Tuner Box NTSC PAL I B/G AV-In $30CAD Free Postage


This will convert a Composite and SVideo source - de-interlacing (flicker fixing) the incomming signal and scan-doubling to the VGA monitor.

These units are 16 or 18bit I am unsure but there pretty good for most Amiga USE.

now to get the realy benefit from any amiga really you will need to convert the RGB to SVideo (Chroma Y/C)

with the A600 and the A1200 this is done for you, all you need to do is clean the signal and amplify it.

I shall post linkies later =D

[Kakaboy]

Originally Posted by Zetr0

now to get the realy benefit from any amiga really you will need to convert the RGB to SVideo (Chroma Y/C)

with the A600 and the A1200 this is done for you, all you need to do is clean the signal and amplify it.

I shall post linkies later =D

So does this mean we need an adapter from RGB to S-video or can we just make a cable up ?

[Zetr0]

@Kakaboy

for the A600 and A1200 you can use just composite and then upgrade to SVideo later.

the A1200 and A600 have SVideo Y/C from the CXA1145 RGB encoder chip, all you need to do is amplify them, and you will have pretty damn good SVideo out.

in terms of visual output I would say its about 80% that of RGB, in actual bandwidth terms its 66%.

well worth the effort IMHO.

[crazyegg]

Hi Zetr0

Thanks for the pinouts.

So, all I have to do is connect the Amiga output R, G & B Analog, H Sync, V Sync and Standard Ground pins to the respective A-22 input pins and I can enjoy my A1200 in glorious SVIDEO?

PS: If it is that simple, than this thing is similar to the RGB-SVIDEO adapter by amigamaniac.com?

Regards,
ed...

[Kakaboy]

Originally Posted by crazyegg

So, all I have to do is connect the Amiga output R, G & B Analog, H Sync, V Sync and Standard Ground pins to the respective A-22 input pins and I can enjoy my A1200 in glorious SVIDEO?

PS: If it is that simple, than this thing is similar to the RGB-SVIDEO adapter by amigamaniac.com?

Regards,
ed...

Zetro says you need to amplify the signal which is what I assume the Amigamanics adapter does .

[Zetr0]

Originally Posted by crazyegg

Hi Zetr0

Thanks for the pinouts.

So, all I have to do is connect the Amiga output R, G & B Analog, H Sync, V Sync and Standard Ground pins to the respective A-22 input pins and I can enjoy my A1200 in glorious SVIDEO?

PS: If it is that simple, than this thing is similar to the RGB-SVIDEO adapter by amigamaniac.com?

Regards,
ed...

yep, pretty much, but Nathans RGB/SVideo converter is cheaper and IMHO a little better as its an all in one plug-in that allows you to change from PAL/NTSC.

Originally Posted by Kakaboy

Zetro says you need to amplify the signal which is what I assume the Amigamanics adapter does .

Infact it does more. Amigamaniacs SVideo adapter actually encodes the RGB signal from an RGB source... so this will work from an A1000 to and A4000T

however the A600 and A1200 have SVideo Y/C onboard the motherboard you just need to tap those lines and amplift them... this will need a little solder skills, some electronics knowledge and my schematic wen I find it, OR you can say sod it and plumb for an RGB to SVideo Y/C adapter like Nathans

[Kakaboy]

Originally Posted by Zetr0

however the A600 and A1200 have SVideo Y/C onboard the motherboard you just need to tap those lines and amplift them... this will need a little solder skills, some electronics knowledge and my schematic wen I find it, OR you can say sod it and plumb for an RGB to SVideo Y/C adapter like Nathans

I wouldnt mind having a little solder action , I have never soldered anything serious apart from wires

If the parts are easily attainable from my local electronics store than im in !

[Zetr0]

@Kakaboy

its very simple (Bill of Materials)

Resistors
33ohm  [x2]
110k  [x3]
10k   [x3]


Caps (radial electrolitic)
100uf [x2] (C1 and C3)


Monolitic (ceramic)
0.1uf [x2] (C2 and C4)


Transistors
2N3904 [x2]

Simple schematic



if you are unsure take a picture and the recipe with you when you pop into the store, they should be able to help.

[Zetr0]

you can source (YI) Y in "luminescence" from Y out [pin 16] of the CXA1145 chip
you can source (CI) C in "Chroma" from the C out [pin 15] of the CXA1145 chip

[kipper2k]

I have that board in a couple of my A600's. I removed the RF module and placed the Svideo output there. It really does work quite good ans is cheap. Only hard part is soldering pin 15 and 16 to the chip. Keep wires as short as possible too so as to prevent external interference.


edit: one thing you must realise is you can only output colour to the correct region monitor/tv otherwise it will display in black & white

[Kakaboy]

Thanks Zetro man . I will do just that . The resistors direction I am unsure of thou .

[kipper2k]

Originally Posted by Kakaboy

Thanks Zetro man . I will do just that . The resistors direction I am unsure of thou .

Resistors are bidirectional... ( any way you want to place them)

[Kakaboy]

Originally Posted by kipper2k

Resistors are bidirectional... ( any way you want to place them)

Cool was hoping that was the case .

Thanks Kipper

[Kakaboy]

Hey Zetro , Does the single ground output you have in the schematic for both Y & C ? Pin 1 & 2 on the S Video .

[kipper2k]

I'll post a small video later today showing the installation and the picture quality. (Any excuse to use my video grabber

[Zetr0]

Originally Posted by Kakaboy

Hey Zetro , Does the single ground output you have in the schematic for both Y & C ? Pin 1 & 2 on the S Video .

yep its a common ground.

Originally Posted by kipper2k

I'll post a small video later today showing the installation and the picture quality. (Any excuse to use my video grabber

sweet! I look forward to seeing this =D

[kipper2k]

btw, there is someone from this forum that is selling these boards prebuilt, i'll check my old messages and try to find the link


edit:.. hehe, that didnt take too long to google....

http://www.amigaworld.de/hardware/s-video-adapter/

now all i gotta do is find out who


edit 2.... found him... DJBase is who i bought them from last year. price was... 10euro each

the components on that board are surface mount, if you want to build your own, do not get the surface mount, get the components with through hole legs.