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Thread: Sync problems with my Sony BVM

  1. #26
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    Quote Originally Posted by PeterWar View Post
    It's a distorted picture moving arround, sound gets outputed correctly to the speakers as well. Yesterday I used my tester and plugged one end of the Csync out of the CXA1145P chip and the other end to the csync megadrive pinout, it measures connectivity! So there is no hardware between those two elements.
    So clearly it is a sync incompatibility thing between the Megadrive with Adapteur RVB cable and the monitor / analogue input board. Perhaps there are some options on the monitor side one can adjust, but I have no experience with this particular monitor. As mentioned, it works fine on a BVM 14M4DE.
    The only last ditch thing I can suggest is to wire the sync directly to the monitor going by the video encoder specs:

    CXA1145_Outputs.jpg

    So basically to the wire you soldered going from pin 11 of the encoder, attach a 470uf capacitor then a 75ohm resistor and then stick the other end in the sync input of the BVM, with all other signals going as usual through the Adapteur RVB cable.

    Obviously no guarantees it will work, but the Adapteur RVB cable uses a different sync circuit (schematics below) so this may be worth a try, just to see if that's the cause of the incompatibility.

    segargb1.png
    Regards, MtothaJ

  2. #27
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    Couldn't I just use the luma or composite pinouts of the CXA1145P chip for sync?

  3. #28
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    Quote Originally Posted by PeterWar View Post
    Couldn't I just use the luma or composite pinouts of the CXA1145P chip for sync?
    Csync would be preferred, but use whatever works for you.
    Regards, MtothaJ

  4. #29
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    I added a 220uF capacitor (rated for 16V) and two sets of resistors in series to make a 72 ohm resistor (my local hardware store did not have a 75 ohm one).

    Following the mmonkey procedure (I actually did not cut the track that leads to pin 7 in the din 8 socket, as it is effectively disconnected (the RGB cable csyinc in is directly wired to the 220uF capacitor and 72 ohm resistance and then to leg 11 of the chip).

    The setup looks like this:





    I still can't get any sync from the monitor, the setup still works with my trinitron CRT though. Checking the schemes I see the standard capacitor is 470uF but everyone recommends using 220uF for some reason.

    After that I tried what MtothaJ suggested and wired leg 11 of the chip-> capacitor -> 72 ohm resistance directly to the csync out of the sega cable. This time both my BVM-A20F1M and Trinitron CRT went out of sync.

    Guys thanks for the help so far but seems that this is not working either :cry: .

  5. #30
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    Quote Originally Posted by PeterWar View Post
    I added a 220uF capacitor (rated for 16V) and two sets of resistors in series to make a 72 ohm resistor (my local hardware store did not have a 75 ohm one).

    Following the mmonkey procedure (I actually did not cut the track that leads to pin 7 in the din 8 socket, as it is effectively disconnected (the RGB cable csyinc in is directly wired to the 220uF capacitor and 72 ohm resistance and then to leg 11 of the chip).

    The setup looks like this:
    I still can't get any sync from the monitor, the setup still works with my trinitron CRT though. Checking the schemes I see the standard capacitor is 470uF but everyone recommends using 220uF for some reason.

    After that I tried what MtothaJ suggested and wired leg 11 of the chip-> capacitor -> 72 ohm resistance directly to the csync out of the sega cable. This time both my BVM-A20F1M and Trinitron CRT went out of sync.

    Guys thanks for the help so far but seems that this is not working either :cry: .
    At this point I think that any further trouble shooting should focus on the monitor / cable setup and not the Megadrive - the console in its stock form and the official Sega scart cable is fine, as is evident when you connect it to a scart TV.

    To be honest I am out of ideas, but some additional things to maybe check:
    - on the BVM side, does the card in addition to the 'in' inputs have 'out' outputs eg. sync out? If so, I would put 75ohm bnc terminator plugs on these, but I doubt that this is the dealbreaker
    - are you using any scart switch in your cable setup?
    Regards, MtothaJ

  6. #31
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    I'm using 75ohm terminators on all four inputs of RGBs, not using any scart switch for the purposes of the testing. The BNC cable is from retrogaming cables.

  7. #32
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    If you are interested in a mod, run the sync signal through a buffer (or any 74LS/HC/etc logic gate) as it is an open collector signal.

    For example, take a 74HC32, solder the CSYNC to pins 1 and 2, and pin 3 is your buffered CSYNC output to go to your SCART connector or RGB cable or whatever you have. The other input pins should be tied to 5V or GND, and the power pins must be connected too.

  8. #33
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    Interesting, 74HC32 is an OR gate, but what would i gain from this? I mean, CSync OR CSync= Csync, I don't get it .

  9. #34
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    Another option to try: get composite video from the cxa1145 and run that as sync to the bvm. If it works but you are getting jailbars etc. you could then think about a sync stripper to get pure sync.
    Regards, MtothaJ

  10. #35
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    I've tried two different megadrives and two different Master Systems 2, all of them where PAL units, but 1 Megadrive and one Master Sytem had the switchless 50/60hz region free mod.

    I can't get any of them to sync.

    Also, I've tried wiring composite video as sync and luma as sync in one of the megadrives, they all sync in my old CRT but not on my BVM. I really don't understand what is happening here, the N64, SNES and NES work all great on my BWM, what's up with the Master System and Megadrive? what's so different?
    Last edited by PeterWar; 08-12-2016 at 05:24 PM.

  11. #36
    JammaNationX
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    Just to make sure, you are pressing the INT/EXT Sync button, correct? INT is for component and EXT is for RGB. Make sure your model isn't the SOG(Sync on Green) model.

  12. #37
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    Yes, the BVM is set to EXT Sync.

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  15. #40
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    Taken from page 7 of the manual:

    The monitor supports the principal formats (480I/480P/720P/1080I) for the digital broadcasts, NTSC and PAL color systems whose horizontal frequency is between 15.625kHz and 45Khz.

    I haven't really noticed untill now that 240P is not mentioned, come to think about it, the monitor shows 480I 60Hz in channel 1 when my Super CIC SNES is playing an NTSC game, it works just fine although there might be a quality loss due to scaling. But can this really cause sync problems?
    Last edited by PeterWar; 08-17-2016 at 08:18 AM.

  16. #41
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    Update: My Neo Geo cable from retrogaming cables arrived today, I've been testing it in my Sony Trinitron CRT, perfect picture, no flaws. I've tested it again on my BVM-A20F1M and got image distortion, this time the games are actually playable, but the image is skewed to the right as seen in the picture.


  17. #42
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    Quote Originally Posted by PeterWar View Post
    Update: My Neo Geo cable from retrogaming cables arrived today, I've been testing it in my Sony Trinitron CRT, perfect picture, no flaws. I've tested it again on my BVM-A20F1M and got image distortion, this time the games are actually playable, but the image is skewed to the right as seen in the picture.

    Regarding retro gaming cables - I have purchased two cables from them a while ago and both were utter crap.
    One thing you can try with regard to the Neo Geo - if the monitor has a VCR mode (probably deep in the extended menus) try toggling it on or off - this seemed to have solved a similar problem: http://shmups.system11.org/viewtopic.php?f=6&t=55732
    Last edited by MtothaJ; 08-20-2016 at 01:00 AM.
    Regards, MtothaJ

  18. #43
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    Quote Originally Posted by PeterWar View Post
    Taken from page 7 of the manual:

    The monitor supports the principal formats (480I/480P/720P/1080I) for the digital broadcasts, NTSC and PAL color systems whose horizontal frequency is between 15.625kHz and 45Khz.

    I haven't really noticed untill now that 240P is not mentioned, come to think about it, the monitor shows 480I 60Hz in channel 1 when my Super CIC SNES is playing an NTSC game, it works just fine although there might be a quality loss due to scaling. But can this really cause sync problems?
    240p is not an actual video standard, it's 480i with the sync pulse suppressed. I would expect your TV assumes 15khz = 480i and this is normal behavior, no cause for concern.

  19. #44
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    I have a BVM-D20F1U and depending on what I want to play I need to switch the VCR mode between on and off.

    On my monitor to switch that on and off I need to:
    Press menu
    Select SET UP
    Select EXTENDED MENU
    enter a password. I tried 1111 and it worked for me.
    VCR MODE is in this menu.

    Once in there if you haven't already I would factory reset all the cards. That helped me out as I have no idea what the people that owned this monitor did with it and it fixed some other weird issues I had like with my Gamecube and trying to use the component cables with this monitor. It also turned on some kHz that were selected off for some reason.

  20. #45
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    Thanks for the input, I've looked on the menu and the extended menu twice, there is no VCR option. I've factory reset all the cards and the BVM too, same results, no sync.
    Last edited by PeterWar; 09-18-2016 at 01:47 PM.

  21. #46
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    I have a BVM-A20F1U too. The A20F1U has a limited sync range compared to other BVMs. I get the same picture with my AES on this monitor. My CMVS wont sync at all on this monitor too. Has anyone found a way to force the picture to sync correctly, with a AES or CMVS on a BVM-A20F1U?

  22. #47
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    That's weird. I've never had a problem with anything syncing with my 20F1U. Stuff that won't sync with my Framemeister (or has issues) syncs with the BVM just fine.


    Quote Originally Posted by mjmjr25 View Post
    No more posts. Jibs wins internet for May 31.

  23. #48
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    We're discussing the BVM-A20F1M, BVM-A models are much less tolerant to off SYNC signals.

    Luckuly retrorgb has found a workaround:
    http://www.retrorgb.com/bkm-68x.html

    Do you know how to update software versions for these bvm? I'm using 1.03 and would consider moving up to
    1.10

  24. #49
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    Quote Originally Posted by PeterWar View Post
    Update: My Neo Geo cable from retrogaming cables arrived today, I've been testing it in my Sony Trinitron CRT, perfect picture, no flaws. I've tested it again on my BVM-A20F1M and got image distortion, this time the games are actually playable, but the image is skewed to the right as seen in the picture.

    That's 100% something wrong with the csync signal line. I just had this happen on a modded SNES Jr with nearly identical distortion, and it was the csync.

  25. #50
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    That's 100% something wrong with the csync signal line. I just had this happen on a modded SNES Jr with nearly identical distortion, and it was the csync.
    this is not something wrong with the csync line I'm afraid.. see below...


    Quote Originally Posted by PeterWar View Post
    We're discussing the BVM-A20F1M, BVM-A models are much less tolerant to off SYNC signals.

    Luckuly retrorgb has found a workaround:
    http://www.retrorgb.com/bkm-68x.html

    Do you know how to update software versions for these bvm? I'm using 1.03 and would consider moving up to
    1.10

    This is correct. The A series BVM is very finicky when it comes to sync and is not really recommended for RGB retro gaming unfortunately. Check the link to RetroRGB. He did a video of his findings and had to use a bunch of equipment just to get things to sync, but even then it is not reliable, introduces lag and only works with certain consoles etc. https://youtu.be/CneMJC-zTf8

    The only way of getting RGB into the A series is with a 68x expansion card. These are crazy expensive and there was only a handful ever made. I think one sold for 2k on ebay not so long ago. Unless you are very fortunate and your monitor already has the 68x card?

    The A series does not have VCR mode.

    You would be far better off selling this and trying to locate a d20f1u as these will play nicely with all your consoles unless of course you're happy playing through composite.

    If multiformat is not important then a 20f1u will do the job and are much more common.


    Also bear in mind.. when 240p is being output the onscreen display will show 480i even when 240p is being output. This is the same for the D series.
    Last edited by daithidownunder; 04-23-2017 at 02:49 AM.


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