New RGB to Component converter design using the BA7230LS

[Flygon]

Excellent. Thank you, man!

For those wanting a direct link. Shipping to Australia seems steep... but I can order multiple for cheap.

To be most clear (and knowing they probably can), they can do 50Hz, right?

[Mrwoodchuck]

Okay here's the schematic I drew up from my last breadboard session with the BA7230LS. I recreated Ace's 5.0 designed, and was using a 5K pot to mix CSync directly from a Saturn I was testing it with. After fixing sync, the contrast of the picture was severely reduced. Not enough that it made it unusable, but not perfect. So I started testing around a little, and I figured out that the Y signal could be fed back into the BA7230LS using the Composite Video amp to amplify Y. A major plus was the fact that Sync is muxed into the CVBS signal. The BA7230LS then matrix's Composite sync into the Y signal thus resulting in "Sync over Luma".

Problem is, Y'sP has to have an input of some sort to produce a video signal at all which leads me to believe that more needs to be in the way of figuring this out.

Hi Swampfox I was messing around with this over the last few days.

I Figured out that due to the way the chip is built, pin 2 combines sync with pin 3 not pin 20.
Thats why you were getting good sync with +5v and nothing with ground.

I tried pin 16 to pin 3 and i got ok image, it was dark.
then i added the 1uf cap and it was super bright, turning it down with a pot made it better but the image was still odd.

I think It might have been something i messed up on..

So i'm not sure if it might be something to try out or I am just way out in left field.

[villahed94]

Excellent. Thank you, man!

For those wanting a direct link. Shipping to Australia seems steep... but I can order multiple for cheap.

To be most clear (and knowing they probably can), they can do 50Hz, right?

They definetly can do 50Hz and other odd refresh rates.
Oddly enough, that's the way I play PAL games. I happen to have a TV that can do S-Video and component in both NTSC and PAL. S-Video tends to crap out (Sub-carrier related issues), but this component box does wonders on PAL.

[erokitsune]

Not sure if anyone can help me. Im using helder's v5.0 version off oshpark and everytime i hook sync up to the board i lose all video. Ive tried sync from the sync in pin, sync from composite video and sync from the sync pin on the multi-out,

If i disconnect the sync composite works, when i attach sync all video signals die but game still continues (sound still works)

If i connect csync directly to the Y jack i also lose signal out of composite. The only thing that doesnt make me lose signal is sync on luma directly to Y but as expected i lose green.

[erokitsune]

I removed the 680 ohm resistor and just ran sync straight to Y, i now get a picture. On my projector it seems fine but on my plasma its way too bright. I still lose composite signal with sync hooked up to the circuit though. Perhaps I should try a pot between sync and Y? Still at a loss on why im losing composite signal though.

[Abelardo]

Hello everyone, new to the forum but I came aboard because of this thread. I want to thank Ace for designing the converter and Helder for the PCB, I've successfully used it on a Neo Geo MVS but it didn't work right out of the box, here's what happened and what I did:

At first I had this weird image waviness on my CRT, and on my LCD TV image would drop out 1-2 seconds every minute more or less. So I applied the fix done by ncorvasce92 (link), basically took the sync output from the LM1881 directly to Y, that helped a lot, waviness on the CRT TV was greatly reduced but still not 100% gone (now it looked like it was flickering/moving very slightly) but LCD TV was now looking great without dropouts.

To finally fix the issue I read somewhere (I think it was in another forum) about adding a low pass filter on the sync line as shown in the LM1881 documentation, in the doc they build it with a 620ohm resistor and 510pf capacitor, I could not source those locally so I used a 33 ohm resistor & 0.01uf cap to get a close enough value, and with this finally all issues were gone.

I'm working on designing a PCB that includes the low-pass filter & the sync on Y directly, never designed a PCB before so it's taking me a while, not sure if anybody else would find it useful but if I complete it I'll share it here

[JamesF]

So the CSync from Pin1 of LM1881 should be injected directly to Y output or through a resistor?
From what I understand the LM1881 output TTL 5v output that needs to be attenuated to consumer standard.

[JamesF]

Is this thread dead of what?

I've attached a schematic with a THS7374 amp after the BA7230LS which Syboxez posted on Discord but I have no idea if it is from Ace.
Ace recommended on discord when I asked "Would you suggest injecting the sync from LM1881 directly to Y through a resistor?".

If by that, you mean a resistive adder (resistor on luminance and composite sync from the LM1881), then yes, though I would do this prior to any 75ohm series resistor + 220uF series capacitor to the display.
Check with a scope to ensure you get 1Vpp with 0.7Vpp for the luminance signal and 0.3Vpp for composite sync after 75ohm termination and you should be good to go.

I wanted to add that there are a lot of schematics on this thread, and newcomers like me still don't know what the correct one to use.