Videonics mx-1 rainbow problem

Hi!

When I convert hdmi signal into s-video or rca, run that through my videonics mx-1 to my crt, i get a weird rainbow flickering on the signal. I’m not sure how I can fix this. I’ve tried using different inputs on the mx-1, tried going between s-video and rca, and i’ve tried running the signal through a vcr which then went to the crt. I am also on NTSC so I’m pretty sure it can’t be that.

I should also note that I connected my Hi8 camcorder to the mixer and fed that to the crt and the colors were normal, also I converted hdmi to rca/s-video and fed that into the crt and colors were normal. So it seems like the mx-1 is only encountering a color problem when the input is an hdmi signal that was converted to either s-video or rca.

I made a reddit post about this where I included a video of the issue so I will link that post here

None of the things I tried solved the problem so I am at a lost for what it could be. I would really appreciate any advice!

The colour cycling suggests to me that there is an issue with chroma frequency mismatch - with the rate of the cycling as beating (like a ringmod) between the interpreted and actual chroma frequencies. Though I realise this is absolutely useless advice since it doesn’t actually help you fix it.

Best suggestion I have is to try different equipment (e.g. a TBC or other framebuffer between the converter and the MX-1) until you find something that works :-\

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Okay thank you! I tried having my video signal pass through a vcr directly after conversion from hdmi to analog. Then the signal went into the mx-1 to the crt. That didn’t fix the issue but I’ll try to think of different routing ways that work with your advice!

As @VisibleSignals pointed out, it is possible that the converter output a slightly out of spec chrominance signal, which then cannot be interpreted correctly by the mixer.

Had a similar issue with HDMI to composite converter and MX-1, rainbow colors, and with Panasonic AVE5 i didn’t have any color at all. Testing the converter on more tolerant devices as a CRT would show color. In my experience, VGA to Composite converter works a bit better than HDMI to Composite with video mixers and such, though my cheap VGA to Composite converter won’t work with my Sony BVM1415P monitor (no colors displayed), so went for the more expensive Startech VGA2VID.

Post from Video Circuit facebook group mentioning the issue

Then, as suggested, adding a digital device in between the source and the mixer might do the trick, as it will probably be able to decode the source video correctly, and then generate its own chroma subcarrier, which hopefully will be in the spec expected by the mixer.

Been looking for this meme since I started writing this post, fits perfectly

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Thank you so much for the detailed response!

That definitely seems like a solution to this problem because all of my gear seems to work correctly however I do have a cheaper amazon hdmi to rca/s-video converter so that is most likely causing a not-so-high quality conversion of the signal, at least not high enough quality for the mx-1 to interpret correctly.

I’m looking at devices such as the Matrox MXO2 that can convert hdmi to analog or vice versa. Im thinking that this more professional type of conversion gear would create a correct signal for the mx-1 to interpret. Do you think that something like a Matrox MXO2 converter/upscaler/downscaler could achieve this? Since you mention the Startech VGA2VID device, it seems like the Matrox MXO2 is basically the equivalent except hdmi to analog rather than RGB to analog.

Are you suggesting that I can add a digital device before my conversion or are you saying I should convert to and from analog and then add a digital device and then convert back again? Sorry if that’s a dumb question I’m just confused as to what you meant.

Thanks again! Yea, old mixers and new converters from amazon probably don’t go together as good as I previously thought lol

I don’t have experience with the Matrox MXO2, but being from a “known” brand (as opposed to cheaper converters), looks like it should output a signal that is in-spec.
I do have more experience with Black Magic devices though, and while doing test for a sync generator, there’s the only ones which output a proper 4.7us sync, all other cheap converters where producing shorter pulses (ranging from 3.7us to 4.3us), which isn’t much of a problem here, but it gives an idea on how some cheaper devices can “take shortcuts”, which won’t cause issue in 95% of use cases.

There’s no dumb question :wink:
I meant adding a device after your converter and before the mixer, as @VisibleSignals suggested, preferably a digital device (such as another mixer, TBC, etc…).
And it is sure confusing, as even if we’re talking about analog video, devices such as mixer, timebase-corrector and of course converters, have analog I/O but involves digital processing. The input signal is converted from analog to digital, and then re-created from digital to analog at the output, that’s what your MX-1 does, though it’s not able to decode the chroma subcarrier (which carries colors). If you got another mixer or TBC that is able to decode the color properly, it will then generate it’s own signal at the output, which might have better spec than the source signal. Though it’s just shifting the issue to another device.

I need to check the MX-1 schematic again, cause some devices allows for tuning of the internal chroma subcarrier, so it is possible to adjust it so it work with your converter, though it may cause issue with other devices.
(MX-1 service manual)

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Okay cool! Yea I’ve heard Black Magic devices are reliable for conversion so I can keep an eye out for that.

ahhh I see what you mean, that makes sense. Yea I feel like rather than shifting the issue to another device, it may be better to go ahead and get a better converter.

I’ll check out the service manual and experiment a little to see if I can just retune the chroma subcarrier to give a correct signal.
Thank you!

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Unfortunately, the MX-1 doesn’t have anything to trim the color subcarrier (page 18 of the service manual, Y2 and associated components). It has a trimmer for the 13.5MHz crystal, though this one is most probably used for sync generation (as 13.5MHz divides nicely into PAL/NTSC sync frequencies).

But sure makes more sense to have a better signal at the input to begin with.

Will test my MX-1 with BM SDI to Analog and report.

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Thank you BastienL! If I figure out something I am going to update this thread with my solution as well. I really think it’s to do with my converter.

I’m experiencing the same issue with video from HDMI on my MX-1. I’ve tried two different (cheap) HDMI converters, with the same rainbow result. Video from other sources, like VCR, looks fine.

So far, the one temporary solution that’s working for me is running the signal through my VCR/DVD players’s video in and s-video out ports before it reaches the mixer. After I do this the picture looks normal. My VCR is a Tobishba DVR620KU.

Has anyone else found a solution to this issue?

My other idea is that it could have something to do with the signal’s refresh rate. My computer is outputting video at 60 hz. I wonder if finding a way to change it to 30 or 29.97 in my computer’s settings would do anything. I could give it a try and report back. To those with more experience, does this idea hold any water?

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