speedlolita
n00b
- Joined
- Dec 16, 2009
- Posts
- 22
Thank you for the clarification.
I have a 3-5 Japanese AES 140XXX system, and I see the checkered board pattern (specially on the blue SNK Logo, similar to the image that Xian Xi posted a while back)
Do I need to do the RGB bypass only?
Many thanks.
Here is an Alternate method I did on a 3-5, this is mod was by customer request.
If you'd like to keep composite video you can leave the 6.8k resistors, 4th cap for composite (says sync in pic) and leave the 75ohm resistor instead of putting a jumper.
One important thing to note is that on revisions 3-5 and 3-6 a bypass mod isn't really needed as they have brighter RGB output than previous revisions. This is due to SNK using the recommended cap/resistor combo by Sony. On 3-5 and 3-6 it is 470uf caps with 75 ohm resistors, on previous models it is 100uf caps with 68 ohm resistors.
Thanks Xian Xi. If I want to keep the composite, how would I do it?
The grid pattern/vertical striping is limited to revision 3-6 because on this revision there is an area called "NTSC only" and the RGB lines are split before they go into the RGB encoder and sent to this area:
http://img215.imageshack.us/img215/9176/aes36be1.jpg
The problem is that these traces run under the clock signal for the encoder and cause some weird interference that shows up as the infamous vertical striping. If these traces, which are totally useless anyway, are cut/lifted from the PCB the striping effect disappears and you get a flawless RGB picture. Earlier revisions don't have these split RGB traces and consequently no striping/checkerboard effect whatsoever:
http://img85.imageshack.us/img85/2975/aes35yl1.jpg
That gamesx article fails to explain the phenomenon and claims that revision 3-5 (the '126000 serial') has a partial striping effect ('checkerboard'), i.e. better RGB than 3-6 but worse than the preceding revisions, which is simply false.
Revisions 3-5 and 3-6 have a brighter RGB output as a result of different values for coupling caps and resistors but this obviously doesn't "dramatically decrease the RGB quality". In fact the new values (470uF/75ohm vs. 100uF/68ohm) are what Sony recommends. In the end the difference between the darker RGB of the earlier revisions (NEO-AES, AES3-3, AES3-4) and the brighter RGB of the later revisions (AES3-5, AES3-6) is trivial and can be compared to a supergun setup with adjustable RGB pots where some will prefer the picture a little darker while others a little brighter.