Super A'Can RGB Mod Help Needed

[GiGaBiTe]

I have a Super A'Can from a customer of mine who needed it repaired since it wasn't working at all. That's since been resolved (bad power switch and some shorted capacitors), but he also wanted to get a better picture out of the console since it only offered RF or Composite video out, both of which are not ideal. Composite doesn't look terrible on my Sony CRT TV, but it does look bad on any frame grabber card or PC TV Tuner we've both tried. It has the usual soft blurriness you'd expect from Composite, which I'm guessing my higher end TV filters out.

From the picture of the logic board I saw before receiving the console, I saw that it had a Samsung KA2195D RGB encoder chip, so I suggested to him that it may be possible to get RGBS out of the console. I suggested one of those cheap generic GBS-8200 converter boards and he bought one and sent it to me with the console several weeks ago, and I've been trying to get it to work correctly ever since.

https://i.imgur.com/3IgVl0e.jpg

I've been able to get it to work, but not work reliably. The RGB lines seem to be OK, but the CSync seems to be having issues. The signal is definitely too weak because if you send it directly to the GBS-8200, it'll have fits and lose sync constantly after about 5 seconds of being powered on. When amplified with a 2SC1815, it behaves better, but it will still randomly lose sync. I've tried to change the amount of amplification on the sync line via the amplifier, and the best I can get it is to only lose sync every 20-30 seconds, rather than fits of multiple sync loss events grouped together. I'm also unable to amplify more than one of the RGB lines at a time, because there seems to be some sort of loop on the power rails. I can amplify R, G or B individually with CSync, but the moment I plug in another line to an amp circuit, the display goes corrupt and the signal is lost altogether. At first I thought some of the parts of my breadboard were shorted together, but I verified they were not, so I have no clue what's happening.

I'd appreciate any help getting RGB out on this console working.

[GiGaBiTe]

Giving this a bump one last time to see if anyone has any insight on this issue.

[Aquamentus]

What about using composite video for sync - use a sync stripper if u need raw csync.

[GiGaBiTe]

I am using csync, there is no other sync source available that I'm aware of.

The Super A'Can is very poorly documented, no surprise since it's a console that never made it to market.

[Bratwurst]

Seems like you can tap composite video right from the back of the RCA port that's at the rear of the system?

[GiGaBiTe]

The owner of the machine doesn't want to use composite video or RF because the output is lousy. It looks fine on my 1992 Sony Trinitron TV, but not a frame grabber or anything modern with composite inputs. You get the normal NTSC artifacting and blur.

Hence why we're trying to get RGB out of the encoder chip.

I have a CXA1145M on order so at least if the RGB out doesn't work on it either, he'll have the option of using S-Video, which is far cleaner than crappy composite video.

[Syntax]

You failed to understand the other 2 so ill repeat it.

Acquire your composite sync signal (CSYNC) from the composite video feed available at the rear of the console.

Use a 5v powered LM1881n sync stripper to separate the sync from the video, use a 460R resistor on the sync output.

With the stripper close to the console you wont have the composite video subcarrier coupling into RGB across the length of the cable which causes crosshatching.

[maxtherabbit]

Try buffering the raw csync through a SN74LVC2G17. It's what I use in my dongles and what the OSSC uses on the RGBHV input

[GiGaBiTe]

I'll try the buffer and see if it helps, will have to order that part though since I don't have any.

You failed to understand the other 2 so ill repeat it.

Acquire your composite sync signal (CSYNC) from the composite video feed available at the rear of the console.

Yes, I don't understand.

The KA2195D provides csync directly on pin 11, is there any benefit from the roundabout method of demuxing it from the composite signal on pin 20 that feeds the composite RCA jack? I can certainly try this method, but I don't see how it would be any different than just getting csync directly.

http://pdf.datasheetcatalog.com/datashe ... Xrtwyr.pdf

I'll order the LM1881N along with the buffer chip suggested and do more experimenting.

[maxtherabbit]

I'll try the buffer and see if it helps, will have to order that part though since I don't have any.

You failed to understand the other 2 so ill repeat it.

Acquire your composite sync signal (CSYNC) from the composite video feed available at the rear of the console.

Yes, I don't understand.

The KA2195D provides csync directly on pin 11, is there any benefit from the roundabout method of demuxing it from the composite signal on pin 20 that feeds the composite RCA jack? I can certainly try this method, but I don't see how it would be any different than just getting csync directly.

http://pdf.datasheetcatalog.com/datashe ... Xrtwyr.pdf

I'll order the LM1881N along with the buffer chip suggested and do more experimenting.

The benefit is that the composite video is going to be driven at a known level and the LM1881 will output a robust signal, the detriment is that it will introduce horizontal shift from the propagation delay inside the sync stripper