Configuring OSSC to work with PC Engine RGB Amp Board

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kruuth
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Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

Hi everyone. Been lurking a little here and was hoping someone could help me.
I have one of these RGB amp boards for my PCE recently:
https://www.ebay.com/itm/115511299323

And I tried plugging it into the OSSC via my Genesis 2 SCART cable but nothing seems to work. Either the TV says that the signal is out of range, or the OSSC says nothing at all. Is there a particular setting I need to use in order for this to work? The TV is a bog-standard Samsung 32-inch LED.
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NoAffinity
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by NoAffinity »

Are you able to get any kind of a signal out of it? Standard composite, audio only?

Tried going to ossc Settings, and Reset Settings? You might have a profile auto loading that isnt compatible with the output from your pce.

Sent from my SM-G955U using Tapatalk
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

I only have the SCART cable for the adapter, however I did try plugging in the composite video cable directly into the PCE and it worked perfectly. I've tried the profile things, and what I have now seems to work with EVERYTHING else that I have tried, from the SMD to the PS2 to the NES.
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Kez
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by Kez »

I assume you are using a CSYNC RGB cable. Unfortunately those adapters are not great, as they are just tapping the unbuffered csync signal direct from the Hu6260. Combined with the resistor in the SCART cable, your sync vpp is possibly just too low for the OSSC to detect. I suspect you may have better results with a sync on composite RGB cable, or reducing the resistor in the Genesis cable from 470 to 330.

You could try messing with the sync settings on the OSSC (link) and see if it is able to grab the signal.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

The cable I'm using is the Insurrection Industries Genesis 2 SCART cable. It says wired for dedicated C-Sync. Does that matter? What would I need to do in order to get it working?
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NoAffinity
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by NoAffinity »

Kez wrote:I assume you are using a CSYNC RGB cable. Unfortunately those adapters are not great, as they are just tapping the unbuffered csync signal direct from the Hu6260. Combined with the resistor in the SCART cable, your sync vpp is possibly just too low for the OSSC to detect. I suspect you may have better results with a sync on composite RGB cable, or reducing the resistor in the Genesis cable from 470 to 330.

You could try messing with the sync settings on the OSSC (link) and see if it is able to grab the signal.
The listing for the cable notes that it is csync or sync on composite switchable.

@kruuth - have you tried switching to sync on composite?

I have one of these adapters, albeit an aliexpress special. I just tested the following with no issues:
MD2 cable to OSSC scart - set to 'MD2' on the adapter switch, which I assume is csync
MD2 cable to OSSC scart - set to 'RCA' on the adapter switch, which I assume is sync on composite; the image noticeably dims
MD2 cable to RT5X scart - SCART-RGB input - set to 'MD2' on the adapter switch, which I assume is csync
MD2 cable to RT5X scart - SCART-RGB input - set to 'MD2' on the adapter switch, which I assume is sync on composite; the image noticeably dims
MD2 cable to RT5X scart - SCART-CV input - set to 'MD2' on the adapter switch, which I assume is sync on composite; dim image
MD2 cable to RT5X scart - SCART-CV input - set to 'RCA' on the adapter switch, which I assume is sync on composite; dim image (no change if adapter switch is switched from 'MD2' to 'RCA', which I find intersting)
Composite Video cable from adapter RCA connection to RT5X - SCART-CV input - set to 'MD2' or 'RCA', get an obviously composite signal, but again no change when switching between the two

Anyway, I know it may not be an apples to apples comparisons, as they are different adapters (although fundamentally, they may be the same...), but hopefully this insight is useful to someone.

Side note/off-topic: playing Super Star Soldier with composite input, post processing set to 'FV-310', vertical filter set to 'smooth', HDR injection set to 'HLG' is a pretty fun experience.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

It will periodically show a signal on the screen--it'll flash for a second but then go back to reporting no signal. The adapter I have doesn't have any sort of switches. It has a single jumper marked "JP ON=FILTER" "JP OFF=BYPASS". This is not the aliexpress Gen2/COMPONENT adapter. It's got a single Gen2 connector and that is all.
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Kez
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by Kez »

This is the PCB I believe, there are no switches. You can see that the csync signal from the EXT pin goes across R2 then straight to the output pin, while the composite video signal is sent through the video amp. R2 in the listing is a 0 ohm resistor, which means the csync pin on this board is wire direct to the csync signal on the Hu6260.

This sync signal is nothing like the csync from a Genesis 2, so it makes sense that a cable with a 470 ohm resistor could cause issues. A cable wired for composite video as sync may fare better, but as I mentioned previously it may be possible for the OSSC to latch onto the signal if you tweak the sync settings as well.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

Kez, you are correct. That is the one. What should I do here to fix it? Are there settings I can try tweaking? If not, I could open the cable and remove the resistor I guess. Would pics of the inside of the cable help?
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Kez
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by Kez »

I posted a link to the sync settings on the OSSC wiki in my first response, you could try tweaking those ones. I wouldn't recommend removing the resistor completely as then the scart pin would be directly connected to the chip, meaning there is a risk of frying the whole console if the cable gets inserted wrong or something

You could try replacing the resistor with a 330 ohm, which would still work okay with genesis, or a 75 ohm which is what the bom for the PCB actually says R2 should be on the oshpark, or you could remove the resistor in the cable and put a 75 ohm resistor in R2 on the PCB. With the last 2 options the cable wouldn't be any good for genesis anymore. Or as I said previously you could try to get hold of a sync on composite video cable for genesis 2.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

Thanks Kez. I wasn't sure what setting there I should try adjusting. My experiences with the OSSC are very limited, I've only ever changed the scanlines.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

I've tried playing with all the settings and nothing has helped. Is there a better cable to use?
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NoAffinity
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by NoAffinity »

If you want to try a cheap cable to test with before spending money on a proper cable, this one will work:

https://www.ebay.com/itm/385190737887

Note it says that the cable is wired for luma sync, but that's incorrect. Genesis (incl. model 2) does not support s-video. It notes that sync is wired from pin 4, which is composite video.
https://gamesx.com/avpinouts/genesisav.htm
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Kez
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by Kez »

kruuth wrote:Thanks Kez. I wasn't sure what setting there I should try adjusting. My experiences with the OSSC are very limited, I've only ever changed the scanlines.
Yeah I am not all that experienced with those settings either, instinctively I am thinking lowering the Analog Sync Vth but it does say on the wiki that's a last resort so it may be possible with a combination of the other settings. Using sync that's within spec is always preferable though.

Any cable which is sync on composite like NoAffinity linked is worth a shot.. although before spending too much on a cable I'd consider getting something like the DBGrafxBooster, the Spark Plug by Tianfeng or EDFX from Krikzz instead, which are better devices overall and will work fine with your existing cable.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

Yeah I am thinking I will try a different cable and then just get the krikzz solution
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

Ok. Well here's where I am on this.
I went as far as reaching out to the creator of the OSSC. I tried diddling the settings and nothing worked. I found my old SCART cable. It's a generic scart cable I've had forever and it works.

However it buzzes like crazy which is why I went with the Insurrection Industries cable.

Now, my question is, what should I do here? I am ok modding the Insurrection Industries SCART cable? What would I need to do in order to get it to work? My knowledge of SCART cables isn't great so I'm really not sure what is going on here.
DejahThoris
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by DejahThoris »

kruuth wrote:Ok. Well here's where I am on this.
I went as far as reaching out to the creator of the OSSC. I tried diddling the settings and nothing worked. I found my old SCART cable. It's a generic scart cable I've had forever and it works.

However it buzzes like crazy which is why I went with the Insurrection Industries cable.

Now, my question is, what should I do here? I am ok modding the Insurrection Industries SCART cable? What would I need to do in order to get it to work? My knowledge of SCART cables isn't great so I'm really not sure what is going on here.
Open up each of them and see how they differ. They're clearly wired differently, so you're going to have to figure out in what way.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

These two pics are from the cheap cable:
Image
Image
These are from the insurrection industries cable:
Image
Image
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Fudoh
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by Fudoh »

It's just about the sync line. That's pin 20 - the yellow cable in the cheap one. There are probably no electrical components in the sync line in either cable, but the other end is likely connected differently. Probably composite video for the cheap cable and maybe composite sync for the Insurrection one.

If you can't open the other end, you can still test continuity. And instead of modding the cable you can also mod the connection on the output connector of your RGB mod.
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Kez
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by Kez »

So looking at the sync pin on both:
Image
Image

You can see that in the cheap cable, it's just a yellow wire with no components. However, in the insurrection cable there is a resistor and a capacitor there. The cheap cable is probably wired like this, getting sync from pin 4:
Image

However the insurrection cable is getting sync from pin 5, which is csync and then has a capacitor and probably a 470 ohm resistor in series with it. So, you may not be able to access the composite video pin at all in the insurrection cable. If there are any loose or cut off wires in there, you could check for continuity with pin 4 and connect that to SCART pin 20 instead, but I can't see any wires like that in the pictures.

Alternatively, you could try replacing the 470R resistor with a lower value one, like a 75R.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

Ok I just checked and based on the diagram there, the insurrection cable has pin 20 going to the pin marked 5. The cheap cable looks like pin 4 is going to sync.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

I'm wondering if there's something on the little mod board I have that is pushing a low value or something. According to the design of the board, sync goes through a 75ohm resistor. I need to figure out if that pin is coming out of the insurrection cable somehow.
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Kez
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by Kez »

The csync line on the board just goes through R2 and straight to the DIN connector. In the picture on the original listing you provided, R2 is a 0 ohm resistor, which is basically just a wire.. so if your board also has a 0 there, there are no meaningful components on the sync line at all.

As I said previously, the csync line going into pin 20 has a 470 ohm resistor on it which is dropping the strength of the signal. It will be inside the heatshrink I circled in my previous post. If you only intend to use this cable for the PC Engine and no longer for a Genesis 2, there are a few things you could do. One option would be to remove the capacitor and resistor from the cable and just connect the wire straight to the pin, and then on the RGB board you could remove resistor R2 and just jump the csync and composite video pin together on the DIN connector.
Alternatively you could replace R2 with a 75R resistor and not jump the two pins.
Or you could try replacing the resistor in the cable with a smaller one.

Again, I wouldn't recommend having no resistors at all (although it may work), as you risk frying the PC Engine if you have a bad SCART connection. Also, any mods you do to the insurrection cable will make it unsuitable (and risky) to use as a Genesis 2 cable.
kruuth
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Re: Configuring OSSC to work with PC Engine RGB Amp Board

Post by kruuth »

Ok well I had a friend who's way better at this than I am. According to him the chip on the right is pushing signal intermittently so this seems to be a problem with the build of the board. I've ordered the krikzz solution.
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