Atari STE to VGA adapter cable...

[Waltermixxx]

well I built my 13 pin din to vga connector out of an old vga cable,
three resisters, and a 13 pin male din I got from digi-key.ca yup
they have them. 

works pretty good with my dell 17" LCD monitor, fills the screen left and right,
not up and down though... will have to work on a few settings? Picture is clean and stable, pure white, and pretty sharp, the monitor indicates 72 hertz at 640 x 400.

The Cable Does not work so good with a samsung...17" monitor, get this strange banding through the picture..... 

in any case, now I just have to get a working copy of Cubase...just to mess around...

[Waltermixxx]

Now for fun I am going to build an RGB to Svideo converter
based on the specs for the AD724 RGB to Svideo chip, and of course
the work done by the folks on the Amiga English Board...

http://eab.abime.net/showthread.php?t=30752

It would be nice to have a nice sharp image on my LCD TV monitor...

[Waltermixxx]

built the rgb to svideo,  but having issues with the green and red signal,
they don't look as solid as the blue, they look striped... very odd...

[Anemos]

Hello im using the rdy PCB RGB to s-video converter from "amigamaniac" on my ST,s just with added 100ohm resistors on RGB lines(each color),working perfect.(also connected with the s-video to cheap VGA converter..)
link: http://www.ultimateamiga.co.uk/index.php/topic,4383.0.html

[Waltermixxx]

hmmm will give that a shot and report back

[Waltermixxx]

100 ohms did not do the trick, tried 100 ohms on each rgb,
and same issue...   I have a picture so I know horizontal and verical sync
are correct.   Blue looks right.
Red and green are strange and interlaced.... will try and post a picture up so you can see,
it's a very simple circuit, and currently running without a capacitor with the crystal.
if I put in a capacitor the picture switches to black and white, nice and clear, but no colour...

[Petari]

...
works pretty good with my dell 17" LCD monitor, fills the screen left and right,
not up and down though... will have to work on a few settings? ...

It is normal by many of the monitors. No real vertical scaling, just doubling of lines.

Considering picture quality in color mode:  isn't better to go on RGB solution instead S-Video ?  Of course, only if there is input for it on monitor: Scart or maybe on HDMI ...

Would like to see schematic of that S-Video encoder .

[Waltermixxx]

here is a link to the schematic I used.

http://www3.telus.net/narmi/schematic.png

this was for an amiga, One thing I should add, instead of FIN going to the ST, it goes to 3.579 colour burst crystal then to ground
with a 20 pf cap in parallel with it ...as per the eagle schematic.
but this image should give you some idea.

I just instead hooked it up to a 13 pin male din.
very simple circuit, the chip does it all...

I added 100 ohm resisters to the rgb inputs

I will try and post a picture of the image I get,
it's not pretty... and I have checked my soldering 10 times...
I may have to go with ready built kits from now on... (sniff sniff)

[Anemos]

Where you getting the 5v power for the PCB? that must be stable ..
Also you need the right oscillator 4.43361875 MHz for PAL or 3.579545 MHz for NTSC.

[msolajic]

Maybe you can try a 10-30 pF variable cap across the crystal, and try to fine-tune the color burst frequency?

[Waltermixxx]

Here is a link to the actual schematic I used.

http://picasaweb.google.com/106022183713139525194/RGBToSvideo?authkey=Gv1sRgCPPzoM610qj5zQE#5560199719428118946

Link to all photos:

http://picasaweb.google.com/106022183713139525194/RGBToSvideo?authkey=Gv1sRgCPPzoM610qj5zQE#

including shots of board...

The 5 volts should be pretty stable, it comes from a 5 volt power adapter (switching power supply) for a usb hub.
So I don't think it would be that, but I was thinking of taking 5 volts from the STE 15pin joystick connector.

I will have to go out and get a variable cap.
I have tried various caps, 10,12,15,18, 22, 30 and they eiter did not change anything,
or cause the image to go monochrome...(nice and crisp image...)

the crystal is a 3.579545 mhz crystal

Thanks guys for your suggestions  I took pictures of the board and upload to the google site...
incase its my build it is vero board I was thinking of trimming connections, and grounding any unused tracks.

[Waltermixxx]

here are the pics... ( just getting used to inserting image links... so sorry for the repitition.... just want to make it easy for any one willing to assist

Cheers

[Waltermixxx]

in the above middle picture, you see the addition of a 470 uf cap for across the 5 volts, an LED to indicate power with current limiting resister, and i added a 2 pin ic socket to try different pf caps for use with the crystal

[msolajic]

I really can't see anything that would cause this circuit not to work.
Walter, can you check the picture quality on the composite output? It comes to my mind, you are using shielded cable for composite video, and regular unshielded wire for S-video.
Also, try to feed the circuit with the shielded wire as well. Just to be sure that nothing outside is causing the interference.

[Waltermixxx]

I checked the composite output and it's the same, and it's totally shielded.  I really think it's the
capacitor or the 5 volts... not sure what else it could be... i am tempted to try it on my amiga 500
and see what it produces, or a standart vga output from my pc (at 640x480)   ...

as far as the unshielded component output, should be fine, the wires are pretty short before getting to
the shielded svideo cable itself, plus as stated above the composite suffers the same issue...
variable capacitor will hopefully solve it...



thanks again for your help.