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Sega Model 2/3 A/B/C - CRX and how I stopped worrying and learned to love the bomb.

Kidkaos said:
I do have the sega model 3 harness and got my Model 3 going. I did read everything you wrote twistedsymphony, but how would I make the adapters for the +5v from the model 3 harness for model 2? I'm confused by that. Not sure which adapters I'd need or how to do it. Do I splice them on the yellow and white wires?
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for 12V I'd create a small harness that is a 3-pin JST NH header on one side and a 2-pin molex on the other so you can plug the model 2 fan into the model 3 harness.

for the 2 additional 5V connector you have a number of different ways to solve it but the one I'd recommend is to find any unused 5V rails on the Blast Power connectors and create an additional 5V harness for Model 2. I don't own a Blast so I don't know what the blast-side of the power situation looks like.

If this is something you can't do yourself then I'd recommend contracting someone like @Lemony Vengeance to do it for you.
 
I don't think there was an official Model 2 harness for the Blast. At least I've never seen one.

twistedsymphony said:
2. you may or may not need to adapt the Video connector (unsure which connector the harness uses).
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The Blast City Model 3 harness uses the 5-pin connector for video.
 
nem said:
I don't think there was an official Model 2 harness for the Blast. At least I've never seen one.
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While I can't attest to an official Model2 harness, there is this Model2b/2c power harness I bought from arcadegame66. I understood 838-10800 boards were used for power distribution, I didn't understand how the 5v and 12v rails worked on it until this arrived. It uses an intermediate cable that splits into two cables each, something I never would have realized.

EDIT: Oh wait, is this not a Blast City PSU with harness for Model2b?

m2b-power-harness.jpg


EDIT2: I can't read. Virtua Fighter 2 is Model2a not Model2b oops. Power distribution should be similar though.
 
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The above harness is for a Versus City. Too bad it's $160 otherwise I would probably buy it.
 
I just found my sega bass fishing harness...is that not a model 2 harness?
 
nem said:
I don't think there was an official Model 2 harness for the Blast. At least I've never seen one.



The Blast City Model 3 harness uses the 5-pin connector for video.
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Wasn't Virtua Fighter 2 exclusively on Astro2 and Blast?
 
nem said:
The above harness is for a Versus City. Too bad it's $160 otherwise I would probably buy it.
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It's too bad I just spent the money to recap a PSU and bought that power cable I posted else I would have bought it X/
 
Kidkaos said:
Wasn't Virtua Fighter 2 exclusively on Astro2 and Blast?
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I've never seen Virtua Fighter 2 or any Model 2 games released in a Blast.

Blast was meant for Model 3. It's right there on the side art.
 
Setting up my House of the Dead (1) board. I now have it receiving power (leds are lighting up) and thanks to people here I have the correct connectors to get going with the rest.

I want to start with the video connection. I tested the voltage on the R, G and B pins and they're coming out at 4.9V. I have a Wells Gardner D9400, here are the input specs:

Input Signals
• Video Input connector 1:15 pin D-sub high density male; VGA
compatible Analog .7 to 1volt level with 75 Ohm input.
• Video Input connector 2: 10 pin connector Analog 2.2 to 4 volt
level at 250/350 Ohm; CGA/EGA 0.156 center header.
• Sync type: TTL & Standard CGA / EGA / VGA/ sync (positive or
negative).
• Sync input: Separate or composite sync from 1 volt to 5 volt input.
• Sync Input Impedance: 2.2K Ohm (H sync and V sync)
• Horiz. / Vert. sync frequency: 15.75 to 40 KHz / 40 to 100 Hz.

So I have to hook it up to the second input which accepts up to 4V. Do I need to put 350 Ohm resistors on the R G and B lines going to that input, and that should bring it down within the 2.2 to 4V range?

Should the sync input also have a resistor (2.2 K Ohm)?

Finally, I checked those lines with an oscilloscope and they are totally constant, which surely isn't right? I though maybe it's just displaying a totally white screen but then looking at the sync line that is constant too (1.5V). What's going on?
 
nem said:
I've never seen Virtua Fighter 2 or any Model 2 games released in a Blast.

Blast was meant for Model 3. It's right there on the side art.
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What cabs had Model 2 from the factory? Astro2?
 
twistedsymphony said:
Astro City II specifically it had an extra large "hump back" to fit the model 2 board.
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That's what I figured. Unfortunately mine was hacked up and I'm having Lemony Vengeance fix my harness to make it Model 2 Compliant after they hacked it and jammatized it
 
I’d been powering my model2 boards with a model3 harness. It works, but basically it's only 4x22awg wires out of the blast i/o carrying 5v to just one of the model 2 5v inputs, and that’s it. I was always cranking my psu to get it up to 5.0.

@dos built me a custom power harness to spec, blast i/o AMP-UP connectors on one end, model2 JST NH on the other. Now I have 8x22awg + 2x18awg carrying 5v to two of the model2 5v inputs, and my psu is much happier about it. I only need to give it a little increase from when the jamma loom was powering my MVS! 5v is happy now.

I still pair this with the original model3 controls harness. Highly recommended! Shout to @ItsBobDudes who built a similar one and got me thinking about it in the first place. If they HAD made a model2 power harness for the blast, this would be it.

EA9EAE8E-342C-4F9D-8DEB-BF2886E2B790.jpeg
24CB51B3-5472-4BE9-B2AE-AF767F66A83B.jpeg
 
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PM sent, after @Mrhide and @Kidkaos I will have two sets of the black AMP-UP connectors left. If demand is large enough I can order more.
 
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