No Sync Intellivision

Viewing 14 posts - 31 through 44 (of 44 total)
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  • #23375
    FredK
    Participant

    Good day Guys,

    My name is Fred and I am indeed the designer of the Intellivision RGB kit. Someone emailed me and linked me to this. I designed the RGB kit several years ago and used the framemeister and the cheap Chinese HDMI scalers to test it. First I have no idea what the OSSC is, who makes it or what it is exactly used for. Keep in mind I’m not active in the console scene, so if this strikes you odd I apologize. I design and build much more for stand up arcade games so I’m more schooled on what is going on in that circle. If you’re just trying to inject the H signal into the V signal off the top of my head I think and and gate would work. I could certainly change the firmware on the RGB kit to make a signal like you show above, but I have no OSSC device to test it and I am unsure how it would effect the RGB working with the Framemiester and Chinese HDMI scaler.

    #23396
    BuckoA51
    Keymaster

    Hi Fred thanks for stopping by! To answer your question it should not affect the performance on other scalers at all. If you want to drop me an e-mail by the sites contact form I can sort out a loan of an OSSC for you.

    #23397
    marqs
    Participant

    To generate composite sync signal from negative polarity H+V syncs, either AND or XNOR gate could be used. The latter would generate horizontal pulses during VSYNC while the former not. Both should be OK for most digitizer chips as long as horizontal pulses are always generated at non-VSYNC region.

    #35971
    FredK
    Participant

    GUYS!!! Sorry for the tremendous amount of time it took me to get to this, but alas I have an intellivsion on the bench with one of my RGB kits installed and hooked to an OSSC. It indeed does not sync to it… So let’s see if we can figure out why.. I think the first thing to try is see if we can inject the horizontal pulses into the Vertical signal.. It’s been awhile since I’ve messed with this so I’ll have to get myself back up to speed on what signals I even have available.

    #35973
    FredK
    Participant

    Okay so after hooking up the scope and checking the Composite signal that goes into the RF modulator I can see that it looks exactly like the timing signals that comes out of my RGB converter (IE they don’t have the H sync in the vertical) So I’m a bit stumped as that should be a signal that any composite monitor would sync up to no problem. I think I’m missing something here or the OSSC is using some sort of horrifically bad IC for the front end… Anyone have any suggestions? Is there a schematic for the OSSC? Maybe I can look at a datasheet and see what the problem with the OSSC is having.

    #35988
    BuckoA51
    Keymaster

    Hey Fred, that’s great you took the time to have a look at this!

    OSSC design is entirely open source so any schematics you need should be on the github or easy to find – https://github.com/marqs85/ossc

    #36000
    FredK
    Participant

    Thanks. I checked the schematics out. I’m a little disappointed that the TVP7002 IC is so finicky. I tried to see if it would sync off from the composite signal from the intellivision before it goes into the RF modulator and it doesn’t like that signal either. The sync signals from the intellivsion seem to be missing a few Horizontal pulses before and after the Vertical blanking and during the vertical blanking. For every other device I have ever seen this is not an issue, but apparently it is for the TVP7002. I don’t have a composite mod on my Intellivision so there is a small chance the signal voltage was off. If someone has a composite mod can you hook it to the sync on green and see if it brings the OSSC to life? I suspect it won’t, but be nice to rule it out.

    So unless I am missing something I think it is because of these missing sync pulses, if so The only way to make horizontal and vertical signals the TVP7002 would like is to start with the clock signal 3.57mhz and try to divide it down into the correct timing. We’d need to sync that with the RGB output somehow so the clock dividers would have to look at another signal from the Inty to reference the timing with.

    Fred

    #36001
    BuckoA51
    Keymaster

    That seems to tally with what Markus was saying on the previous page. I guess this isn’t something trivial to fix then 🙁

    #36037
    FredK
    Participant

    For the sake of my own curiosity I built a composite mod and hooked it to my inty. I then fed that to the AV2 Sync on green and it was a no go also. I pulled out my Trs-80 color computer with a composite mod and the OSSC synced right up to that. Comparing the 2 signals (inty and Trs 80) It looks like the inty is missing the pulses for interlaced video. If anyone with the skills wants to work on something with me (while I have this stuff hooked up and it’s on the bench) maybe we could design a new AY-3-8915.

    #36091
    BuckoA51
    Keymaster

    I’ll point both Bas from BetaGamma and Markus towards this thread 🙂

    #36843
    ReidBecker
    Participant

    Hi…I had the intellivision -> scart cable -> scaler -> hdmi monitor setup working. The scart cable is some generic one I bought off ebay to demonstrate my mod is compatible with Genesis 2 rgb cables. Pulling one of the V1-V4 wires verifies the scaler is processing rgb and not composite video. The picture quality is better than in the photos below but is still not super sharp. The scart cable is neither 75 ohms or ground shielded so that is the first thing I want to try changing. It’s also a cheap scaler so it could just be that. Either way I’m happy that my mod works with standard unmodified equipment.

    prototype pcb assembly

    #36844
    FredK
    Participant

    You’ve had it work with the OSSC?

    #36849
    BuckoA51
    Keymaster

    I think he means another cheap scaler?

    #41357
    niugnep
    Participant

    I just wanted to thank everyone for documenting so much on this issue. I just came into possession of a PAL Intellivision with the ZOE RGB board installed. I was pretty bummed to realize it would not work with the OSSC. It shows up on my PVM fine, but totally ignored by my OSSC with the same message as others.

    I doubt anyone has a solution as it would have been mentioned. However, I was curious if this is something someone is looking at, might be addressed with the Pro version of the OSSC, or what I might do to assist or resolve this issue (if there’s any hope at all).

    Thanks!

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