buttersoft wrote:I use THS7316's to connect to my arcade monitors from a PC source. Without amplification the picture is only just visible, it's night and day for me
Part of this effort later down the line is to also amp my CRT_Emu based MAME setups so very interested in how you are achieving this. Saves the need to use a J-Pac for amping while also allowing for joystick control rather than keyboard emulation of the J-Pac. Perhaps you can post some pics of your PCB?
buttersoft wrote:The RGB lines need to be terminated at 75R to ground on the way into the amp but do not want caps, and I just use 1K pots on the output lines and nothing else, into the chassis RGB lines.
Ahh, so there is the key. So if I understand what you are saying, I have the 75 ohm resistors on the output without any termination to ground. I should instead have the 75 ohm resistors grounded just before the input?
I suspect you have the 1k pots to control either brightness or contrast on each individual RGB line. Is this necessary given the chassis has brightness and contrast controls already and RGB cutoff and bias on the neckboard? Also, do you struggle tuning the individual pots on the RGB lines? Or do you use a triple gang pot to adjust the three RGB lines all at once?
buttersoft wrote:I don't bother amplifying sync, just combine it with some resistors and maybe a diode, into the chassis. Also, make sure not to use the caps across the power supply rail - or anyway they produced noise issues for me. Given the only difference between a PC and a SCART console is sync, maybe try simplifying the circuit like above? Also, what chassis are you using?
I don't have any problems with sync on my CRT_Emu setups or with the console hookups. My console SCART cables have Csync built in. Plus I am using the Sync Strke to strip sync. Other than that, I don't alter the sync at all. I just run that into my chassis on my console and CRT_Emu setups.
So that cap I have bridging ground and 5v should be removed? Weird, even the TI's documents say that it should be there. But I'll give it a shot.
I'm using a variety of chassis. But mostly Wells Gardner K7000 and Nanao MS8. On the K7000, don't have much issue other than needing to recalibrate the settings on the chassis since it can accept an AC-coupled video signal. But on the Nanao MS8, there is no adjustment I can make to make it look right.