Menu

Voultar MD1 RGB Bypass on VA4

Home Forums Repairs and Mods Voultar MD1 RGB Bypass on VA4

This topic contains 15 replies, has 6 voices, and was last updated by  BlueStinger 4 months, 1 week ago.

Viewing 15 posts - 1 through 15 (of 16 total)
  • Author
    Posts
  • #24092

    nzChris
    Participant

    Has anyone been able to get the Voultar RGB bypass board working on a VA4 PAL board?

    I’ve followed the instructions and checked continuity of every connection but am getting ‘no sync’ on my OSSC or direct into TV.
    I have tried this on two VA4 consoles and now neither of them work.

    Here is an updated photo with signals now pulled directly from the chip as Voultar recommends, since this photo I have also moved the power and ground directly to the 7805 (furthest away from the DIN).

    View post on imgur.com

    #24198

    BuckoA51
    Keymaster

    We’ve actually been seeing some strange things with PAL Mds and sync and we’re still investigating.

    #24214

    nzChris
    Participant

    Ok thanks, hopefully it’s something simple = )

    #24556

    renovigo
    Participant

    Hi,

    As a matter of fact, I found a way to connect the Voulat board and get a decent picture.

    There are a few differences to take in consideration toward the installation guide :

    – First, lift RGB pins on the VDP (the big tricky part) but leave the SYNC one on the board, don’t lift it. You can connect the Voultar board to the corresponding pads, and also connect the CSYNC pad to the CSYNC pin on the VDP.
    – On the back of the board, discard the mainboards pull-up resistor for the CSYNC signal and install a 2k2 resistor as it’s shown in the installation guide. As well Locate Pin 10 of the CXA1145 on the solder side and cut the track as shown in the guide. We will not cut anymore pin on the CXA1145.
    – Finally, we need to connect RGB out of the Voulatr board directly to the 8 pin DIN. Again, on the back of the board, locate R, G, and B of the DIN connector and solder them to the RGB out wires of the Voultar. Concerning the SYNC out, you can solder it directly on the SYNC leg of the DIN connector on the upside of the board.
    – For +5v and GRD, take them on the 7805, as you did.

    The results are pretty good, even on a CRT screen.

    Voilà !

    #24562

    nzChris
    Participant

    Hi Renovigo,

    Thank you for your reply, I have had this project on hold for the past month now with no progress.
    This evening I managed to get it to work after seeing a number people connecting the +5v to the csync on the voltar board with a 2.2k resistor as below.

    All of a sudden I have a signal on my OSSC and it is operational.
    The colours are now vibrant, but there are huge vertical lines everywhere, I assume these will be corrected by swapping out the SMC components to the new values Voultar has suggested.
    I bet if I tried your way it would have worked also so thank you for taking the time to respond.

    cheers,
    Chris

    #24572

    nzChris
    Participant

    Okay it seems like the issue was resolved on the newer version of the board!

    https://voultar.com/index.php?route=product/product&product_id=73

    https://voultar.com/image/cache/catalog/SegaRGB-500×500.jpg

    You can see on the newer boards the +5V has a link to the CYSNC and the component values have been updated also.
    Hope this helps someone else as I’ve been scratching my head for a long time.

    Chris

    #24585

    nzChris
    Participant
    #24596

    renovigo
    Participant

    Hi,

    Thanks for the information Chris. I didn’t see there was a new revision for the board, and I’m glad you find a solution on your own.
    But do your last post shows the image you get ? Because it seems that there are still some interferences isn’t it ?

    #24600

    nzChris
    Participant

    Yes this is what it looks like now, with the new revision the capacitor values etc have been changed so I am assuming these would fix the lines. TBH I cant figure out how and where to buy the smd components so I have ordered the new board direct from Voultar.

    #24649

    nzChris
    Participant

    Ok this should be my final post, I chatted with Voultar and managed to get it working.
    The last part of the puzzle was lifting pin 50 on the VDP which is the redundant subcarrier.
    You might not be able to tell from the photo but it is razor sharp and not even a hit of jail-bars to be seen in any light.

    View post on imgur.com

    #24656

    renovigo
    Participant

    I’m glad you made it finally ! It looks perfect to me.
    Something I find strange though, is that in my case I didn’t have to add an extra resistor on the board itself. I did have the pin 50 lifted but I get very fine results with no extra routing on the Voultar board. Would it be better if I did add some ?….I’m maybe a little lazy to re-open the console again…

    Anyway, well done !

    #25645

    renovigo
    Participant

    Hi,

    It’s just an information post, following this thread

    I removed completely the CXA1145 on my VA4 PAL MD, as it has an rgb bypass, I followed some installation clues I saw on the internet (here for example), telling myself that it worth the try -and it kind of made sense regarding the all bypass purpose-.

    So I did it. And it worked indeed. BUT it didn’t worked everytime.

    Everytime the console ran for more than 20 minutes maybe, once you turn it off and change the cartridge, the system didn’t boot anymore. No picture, no sound, nothing.
    The weird thing is, if that happens and you open the console to see what’s happening and try to “repair” (checking voltages, make fresh solder, etc.), it can boot again ! You can play for 30-40 minutes. But again, when it turns off, it doesn’t boot anymore.

    SO, if I would advise something for people who are installing an rgb bypass to a VA4 MD PAL system, DON’T REMOVE THE CXA1145. I guess this chip makes more than just video encoding, maybe some clock purposes or whatever. Or maybe it works only on NTSC systems.

    If anybody encountered the same issue, or on the contrary, didn’t faced any problem at all, feel free to share !

    Thanks !

    #26221

    infidelity
    Participant

    Hello I have a question regarding a bypass that I’ve done last year,using one of the first bypass amps released (its green and has 3 vertical capacitors)

    My system is a model 1 VA6. My method I performed, was lifting the R,G,B,Csync pins from the VDP off of the motherboard, soldered cdrom audio cables from those pins, to the bypass amp. I also have pin 50 from the VDP cut.

    The picture I get from my ossc with firebrandx’s 320×224 optimal timings is incredible!

    With that said, I still have very very faint vertical lines,they are really noticeable on a light gray background, example being the hidden stage select screen for Altered Beast.

    Now, i did this before Voultar released his version of the bypass. I have removed the 3 pull up resistors on the bottom of the motherboard, and I’m bypassing the CXA Sony chip entirely.

    Why, when I’m running directly from the VDP, to the bypass amp, am I still getting vertical lines? What am I missing, or need restored?

    I’m using a euroscart rgb cable wired for csync.

    Please help, thanks!

    #26989

    BlueStinger
    Participant

    I’ve removed some CXA too and I had the same issue. The console can run for an hour without issue, but you can’t reset the console or change game or it won’t boot anymore. 5-10 minutes later I was able to restart the console. After a while, I couldn’t get past the TMSS screen later the console simply didn’t boot anymore. DON’T REMOVE THE CXA from (some ?) PAL consoles !

    @infidelity
    I too have faint jailbars no matter what I do. I’ve done it in different ways :
    Removing CXA entirely
    Lifting CXA’s RGB and CSync pins
    Taking +5V and GND from various places
    Lifting pins from the VDP
    Cutting traces on the back of the board
    etc

    No matter what I do I still get a bit of jailbars. From my experience, the best place to get +5V and GND is the 7805 voltage regulator (which you can replace by a 1.5amp if you feel like it) and also twisting the +5V and GND cable together to cancel the electromagnetic field. Routing Csync as far as R, G and B as possible doesn’t seem to make a difference. Lifting subcarrier makes NO difference (Voultar actually confirmed that, I quote him : “So long as you’ve lifted the pins of the vdp, subcarrier can do whatever he wants in life”). And I wire R,G,B and Csync directly to the AV out connector under the PCB, routing the wires in the holes the RF use to occupy.

    I’ve seen BayCityAnri adding some 47µf caps on the board, near the vdp, no idea why or if it’s relevant for PAL consoles etc.

    So yeah, sorry guys, this message is mostly a “I’ve made the same mistakes and they are indeed mistakes” comment but at least someone might find this info while searching for it. I find that there is a lack of info on this very common mod for some reason.

    #26995

    hardyhell
    Participant

    does anyone have a final guide with Pictures about how to make the mod in a Pal Va4 with the latest voultar board sold by videogameperfection?

    thanks guys

Viewing 15 posts - 1 through 15 (of 16 total)

You must be logged in to reply to this topic.