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lethargyman

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The OSSC documentation says

"The AV3 input is a VGA/HD-15 connector which supports video in RGBHV, RGBS (pin 13), RGsB and YPbPr formats. RGBHV and RGBS modes require clean TTL-level sync signals and cannot extract sync from composite video or luma."

If I'm reading that right, then the sync should be unprocessed for AV3 since JAMMA is RGBS format (I think...)
 

evilsim

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@lethargyman, a lot of arcade boards output TTL Csync but it doesnt hurt to run it through a stripper/cleaner anyway ; this is what @Frank_fjs 's syncbooster does (you can grab gerbers from his minigun post page1) it strips 8 pin mini din input's sync to TTL csync, outputting it to a db15 which plugs directly into the OSSC. i have spares and will be buying more PCB's soon. syncbooster is great, i also use it with my RetroScaler A1 as it gives me a no-fuss, always sync-able solution. Also, while jamma is RGBS format (whatever that actually means), jamma sync can be in so many forms, its quite rare for a console or even arcade board to sync up on an OSSC on AV3 using RGBS option.

needless to say im very excited about the new betsubetsu too! (ive already annoyed @buffi about it a bunch and he knows I am keen for the gerbers and BOM, when they're ready)
 

lethargyman

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Thanks for the explanation @evilsim I should've known this would be a lot more complicated! BTW, if you're planning to sell the syncbooster then I'd definitely be interested :)

One reason I thought this might work is that I can get the OSSC to sync up perfectly with my F3 by using a VGA passthrough adapter on the SCART from the control box (which as far as I know just passes RGBS through). Of course by not using the Betsu Betsu that means I don't have its RGB attenuation which is definitely not good for the OSSC.

Sorry for dragging your thread off-topic @buffi !
 

buffi

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BetsuBetsu uses same output as Minigun, so that syncbooster should work well
 

buffi

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Cleaned up the schematic a bit. Looks nice now!
rELrvLv.png
 

Velyks

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Sick project. Would you be willing to sell these as a kit or sell just the PCB?

Edit: Also would you consider a version that uses a regular sized DIN 8 with the sega megadrive/genesis pinout? The RGB cables for those are an order of magnitude cheaper than the mini din ones (that I've found)

Double edit: Looks like megadrive 2 is a mini-din, so I guess it would just be a pin swap
 
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buffi

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Selling pcbs: Absolutely.
Kits with parts: Probably yeah, at some markup.
Assembled: Possibly a few. Will mark those up quite a bit though since soldering these together takes a while, and i cant see doing large scale manufacturing. If I do this, expect it to be expensive.

Design, schematics and whatever will be open though, so once it’s final, people can build and sell these for whatever price makes sense.
 

buffi

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I probably wont make a regular size din version btw, since i like mini-din and I dont want to maintain a second version.
 

buffi

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Soldered it up. Wont have time to try it out until later today though.
Other than some minor silkscreen updates, I think this design is close to final. Might split this up into a new thread then since this one is a bit confusing with the earlier non jamma design as well.
duW2roy.jpg
 

evilsim

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the voltmeter on the minigun has the holes directly below it, which matches up with the voltmeter power pads. i actually use these. I remove the wires from the voltmeter and solder some spare resistor legs directly in place, then those legs go straight through the pcb and get soldered to the base of the minigun pcb. this fastens the voltmeter to the pcb well. However, running wires to elsewhere on the PCB is fine too. Just what I do.
 

buffi

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the voltmeter on the minigun has the holes directly below it, which matches up with the voltmeter power pads. i actually use these. I remove the wires from the voltmeter and solder some spare resistor legs directly in place, then those legs go straight through the pcb and get soldered to the base of the minigun pcb. this fastens the voltmeter to the pcb well. However, running wires to elsewhere on the PCB is fine too. Just what I do.
Yeah I know. I was considering re-routing parts of the PCB to allow for that but decided against it.

Honestly I dunno if I'll ever stick a voltmeter on this thing, but I had some space for the hole so though why not!
 

buffi

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Just to show my test-rig for these things as well.
Before plugging them into my cab, I test them on a cheap CRT by powering it through a Minigun, and use headphones for audio.

Works great!
bBWBL75.jpg
 

dingsbums

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Nice :thumbup:
How is that video out wired ? Is it the same pinout as a Mega Drive 2 RGB cable ?
 

KmanSweden

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Soldered it up. Wont have time to try it out until later today though.
Other than some minor silkscreen updates, I think this design is close to final. Might split this up into a new thread then since this one is a bit confusing with the earlier non jamma design as well.
duW2roy.jpg
Damn that’s nice!
 

rememberizer

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Thanks for making this open source, buffi! Excellent project!

Are the sync and RGB outputs at 0.7vpp / 75ohm levels? I tried to build the video circuit and split from the jamma harness, but my GBS Control scaler can't sync to CPS2 at all. It can grab MVS signals but the image shakes occasionally, maybe once every 10 seconds (not consistent). The scaler works great for console input as well as Raspberry Pi, so it's definitely working well. Is there anything I can add to the circuit to get the output to console levels?
 
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