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 Post subject: Triple Bypass-modded Genesis 2 no longer works with 32X
PostPosted: Mon Jun 29, 2020 3:40 am 


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Joined: 28 Jan 2012
Posts: 927
Location: San Jose, CA
Recently I acquired a VA3 Genesis 2 console and had it modded with a v0.3 Triple Bypass board to get better audio and RGB quality out of it. By itself, the RGB output from the Genesis looks incredible and the audio is even better, sounds like everything went well right? But when I decided to try it with my 32X, my OSSC could no longer find a useable sync signal and composite video also stopped working properly through the 32X (just a *very* dim rolling picture). Here's a rundown of what's going on:

    - The 32X itself still works, I tested it with my unmodified JP Mega Drive 2 and everything worked fine.
    - I'm using an RGB SCART cable that uses composite video for sync. The same cable works on the Genesis 2 without the 32X connected and my OSSC has no issues with it.
    - Pins 21 to 23 have been lifted on the CXA1645 so the original RGB signals don't interfere with the new signals from the 3BP board. Pins 2 to 4 on the encoder have not been lifted as I wanted to preserve composite video.
    - The 3BP has been mounted on the underside of the motherboard and is soldered directly to the pins on the mini-DIN AV connector.
    - The RGB signals are being taken directly from the VDP and go straight into the 3BP.
    - The composite sync signal has not been touched in any way.
    - I'm also using the original link cable that came with the 32X.

I'm hoping to sell this console off soon as I'd prefer to keep the Mega Drive 2, but I don't want this to become someone else's problem nor do I feel comfortable selling a console that is no longer compatible with a major add-on. Any help would be greatly appreciated!


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 Post subject: Re: Triple Bypass-modded Genesis 2 no longer works with 32X
PostPosted: Mon Jun 29, 2020 12:23 pm 



Joined: 05 Dec 2012
Posts: 497
Sounds like you installed everything correctly. You don't happen to have an oscilloscope, do you? My first guess would be that there's an issue with the csync output of the Genesis 2 and the easiest way is to test that on a scope.

Next, if you have a Sega CD, try connecting it to that and trying 32x. There's an issue with some Genesis 2's not terminating the expansion port pins properly and if it works with a SCD, but not without it, that's an issue.

Also, we've been battling 32x issues for months: I had a few that would work on some consoles, but not others, regardless of 3BP or stock. I ended up selling two to friends and telling them if it doesn't work to send it back...but both worked on their 3BP-modded Genesis consoles, so there's still something else I'm missing.


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 Post subject: Re: Triple Bypass-modded Genesis 2 no longer works with 32X
PostPosted: Mon Jun 29, 2020 3:14 pm 


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Joined: 05 Mar 2018
Posts: 1268
The 32x has meme level build and design quality


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 Post subject: Re: Triple Bypass-modded Genesis 2 no longer works with 32X
PostPosted: Mon Jun 29, 2020 4:11 pm 


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Joined: 20 Jul 2017
Posts: 561
Did it work with the 32X prior to doing the mod? I have a couple MD2s that just don't work with my 32X totally unmodded.


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 Post subject: Re: Triple Bypass-modded Genesis 2 no longer works with 32X
PostPosted: Mon Jun 29, 2020 5:24 pm 


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Joined: 28 Jan 2012
Posts: 927
Location: San Jose, CA
Kez wrote:
Did it work with the 32X prior to doing the mod? I have a couple MD2s that just don't work with my 32X totally unmodded.

Yes, it worked perfectly fine with the 32X before the 3BP. I think something happened with the sync signal because I can still get some kind of video via composite, but it's super dim and rolls diagonally. The OSSC doesn't even pick it up. I'm curious to see what RGB is like on a CRT, but my PVM is in storage at the moment.


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 Post subject: Re: Triple Bypass-modded Genesis 2 no longer works with 32X
PostPosted: Mon Aug 03, 2020 6:03 am 


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Joined: 28 Jan 2012
Posts: 927
Location: San Jose, CA
I came back to this last night and undid the video portion of the Triple Bypass by removing the added wires and setting back down the RGB output pins on the encoder. Nothing changed with the 32X and when I plugged in the Genesis by itself, I got a sync signal and audio, but no video whatsoever. The CXA1645 also seems to be getting hot soon after power up, so it looks like I somehow killed the video encoder. Fuckin' hell.


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 Post subject: Re: Triple Bypass-modded Genesis 2 no longer works with 32X
PostPosted: Tue Aug 04, 2020 3:31 am 



Joined: 13 Mar 2011
Posts: 1055
Location: Toronto, Canada
I also heard about this from a person who installed the 3BP on their Genesis 2. If all you do is lift the RGB output pins don’t see how this can effect the 32X as csync is untouched and goes out the 9 pin miniDIN

Thanks for testing the system with the mod reverted. It does sound like somehow people are killing the CXA chip. Maybe too much heat lifting the 3 pins?


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 Post subject: Re: Triple Bypass-modded Genesis 2 no longer works with 32X
PostPosted: Tue Aug 04, 2020 9:25 pm 


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Joined: 28 Jan 2012
Posts: 927
Location: San Jose, CA
leonk wrote:
Maybe too much heat lifting the 3 pins?

That might have been the case? I didn't leave my iron on it for very long so I guess these are just really sensitive to heat.

When I do a Triple Bypass on my Japanese MD 2, I'm not even going to bother with the video side and will be installing it topside.


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