help with a520 s-video hack

[Damiga]

Hi,
 
I've spent last two days following these instructions: http://members.iinet.net.au/~davem2/overclock/a520.html
 
Is there someone else here that has done it?
I need some assistance because I cant get it to work.
 
I've lost count on how many times I've gone through the instructions and checking that I've followed all the steps.
 
Help?

[Damiga]

Had a look and it seems pretty straight forward enough, though I didn't think anyone would actually be using an old a520 these days...
 
Not sure why your using it or needing to convert it to an S-Video signal (RGB is much better) but if you do need S-Video it may be simpler to buy a ready made Composite to S-Video converter box...

Well I wasn't using it and I wanted something to do =)
 
Normally I use an old CRT with SCART connector, but I also have a projector that hasn't got SCART. The projector has Y-U-V connections so about a week ago I bought a second hand SCART->Y-U-V converter so I could hook it up.
 
It gives a nice sharp image but unfortunately there are som slight vertical "ghosting" of the colors.
 
So since I had an A520 that was of no use to me I decided to give it a try and see if the converted A520 would produce a better image than my scart-yuv converter

[Damiga]

And by the way...
 
You should know better than to ask a geek why he tries to do something.
The answer is as always, "because I can" =)
 
Although in this case, I couldn't :/

[Damiga]

Franko
 
completely useless post as usual why bother posting on every thread. And what kind of moron tells somebody to run a composite to svideo adaptor that ruins the whole point of having y/c.. wake up. Every time you post a stupid post like this I will be there to tell you to stop the insanity. You are growing tiresome to productive amigans.
 
As far as a520 svideo hack thats a nice project, too bad it wont work for NTSC a520s according to the doc? or can it..
 
@ op when you say "not working" what exactly do you mean? just a black screen? are there scanlines or color?

Just a black screen and the projector displays "no signal".
I tried flipping the C and Y connectors just in case I wired them wrong, but then the projector goes crazy, fans spinning up =)
 
I was thinking that maybe there are som crucial points on the circuit board that I should measure and compare with someone that has a working s-video hacked A520

[Damiga]

True... but it would be simpler to buy a Composite to S-Video convertor to use with a projector or better still an RGB to S-Video convertor for a really clean picture...
 
As for the hack, one of my mates did a similar hack years ago on his old A520 as at the time he didn't have a monitor and the TV he was using only had composite & S-Video connectors, I recall though that the picture quality was quite poor though...

I'm not looking for the easiest way :laughing:
 
I have composite on the projector but the image quality is not so good, and my A500 only gives b/w on composite so it's not really an option for me.

[Damiga]

Franko
I'm tired of you polluting and hijacking threads why dont you try to GO OUTSIDE and at least TOUCH A GIRL
 
@ OP
 
Try with a regular tv or monitor not the projector.

The only other TV i have with s-video is my LCD in the living room but I'm afraid it might get fried, the projector was acting up when I tried the A520 on it.

[Damiga]

Ahhhhhhhhh Good old Magnetic why is it every time i see your name or a post from you i want to break every bone in your body?? hmmm but i digress..
I have built one of these about 4 - 5 years ago when i didn't have that many monitors.
 
It was painful but it worked.
I know it sounds silly but have you followed all the instructions properly?
I would check to make sure all your cut and hacks were right.
Have you tried this on another TV (could be the projector doesn't like the A520?)
I will have to dig through my boxes to see if i can find again (if you want me too).
 
This is actually a nice mod to do if you only have TV (without SCART) to work with much better picture than a stock A520.
 
P.S.
I assume you double check all your orientation of your resistors with the colour image?

I will go through the instructions again, I've done it about 5 times so far so one more time won't hurt :lol:
 
It would be great if you have the time to look for it and check if it's made the same way as in the instructions I posted. I'm very interested in how you connected the cable, that's the one thing I'm a bit unsure of.
 
Resistors don't have wrong/right orientation.

[Damiga]

Ok, enough off-topic!
 
Don't make me call Arnold and make him go kindergarten cop on all your asses!

[Damiga]

@Damiga

Not tried the A520 hack but are you sure you are matching a PAL A520 to a PAL Amiga?

You also mentioned a SCART to YUV converter that had some Ghosting issues. The Amigas CSYNC signal is not compatible with modern video devices un-modified. You need to attentuate the output using a 330 ohm resistor. My SCART cable diagram is shown here:

http://eab.abime.net/showthread.php?t=47281

What Amiga do you have?
There are easily made hacks to add S-Video to the A600/A1200 or you can purchase an RGB to S-Video adaptor from Amigamaniac.com, though this is not as fun as hacking something together yourself

Ian

Hi Ian,

I've actually modified cable using your instructions earlier, it works great with my old CRT TV, so thanks for that =)

I also bought an amiga->scart cable that I've been using with the projector and the scart/yuv converter. The one I made myself with your instructions didn't work with the scart/yuv converter but the one I bought did.
And the cable I bought don't work on my CRT TV, The picture "rolls".

I actually had the same problem with the homemade cable on the CRT before I modified it with your instructions. The only modification was actually changing a resistor(I think it was a 180ohm that I changed to a 330ohm) so I guess that the cable I recently bought has a resistor lower than 330ohm and for some reason that makes it work with my projector. I haven't bothered to investigate that further since I could piece together a working combination of cables and CRT/projector.

On to the a520...
I'm pretty sure it's a PAL A520, The NTSC "jumper" on the circuit board is open(looks clean so I doubt that it's ever been closed) and the crystal is 4,something MHz and I understand that a NTSC version should have 3,something.

I've tried the A520 on my Amiga 500+ and on my A600, I don't dare to try it on my A1200s before I got it working on the a500 or a600.

I know there are other options for me than modifying the A520, but I'm not doing it out of necessity, I'm doing it for fun and it's a challenge

[Damiga]

Hello!
I didn't try the A520 mod for Y/C output, but since you speak about the YUV input of your projector, remember that YUV is DIFFERENT from Y/C.
Y/C means separated luma (brightness) and chroma (color) signals
YUV (also YCbCr) means luma signal (Y), U blue color minus luma signal (B-Y), V red color minus luma signal (R-Y)
 
So Y/C output is not compatible with YUV.

Yes I know, and I'm NOT trying to connect it(modified A520) to the YUV/YCbCr ports on the projector.