PC Engine noob questions (picture and audio)

[Jonesyy]

Recently bought a pc engine core grafx. Since I'm very new to pce I have a few of questions:

1) My pce has an rgb soft mod - see below. It came with a scart cable, not a fancy one, just an unbranded thing that came with the soft mod. I have that scart cable going into a scart to BNC lead which then goes into my sony pvm. The picture is fine, but there is quite a lot of interference on the audio. Not really noticeable during game play with music, but if I'm doing something without game music such as navigating menus etc, the interference is really noticeable. Any idea why this might be? Could it be a cheap/not very good scart cable? The scart to bnc adaptor is from retrogamingcable which I bought a while ago for connecting my megadrive to my pvm. The megadrive by the way has much less audio interference than the pce. (The megadrive has a retrogamingcable rgb to scart and scart to bnc, where as the pce uses the same scart to bnc but has its own pce to scart cable that I did not buy myself).



2) If I disconnect the rgb mod and just use the standard pce tv lead (which would be called 5 point din to component I guess?) to connect to a different consumer crt tv set I have, the sound has no interference, but the picture is black and white only. Any ideas why? Would this have something to do with Japanese using NTSC and my tv is PAL? Do I have any way around this if I did want to use the standard tv lead on a standard (non bnc) crt?

3) If I ever decide I want to get into pce cd's, what options would I have, considering the the cd rom rom thing seem to plug into the pce expansion slot, which is currently in use by my rgb soft mod. Would I have to get an rgb hard mod done to keep the rgb?

Thanks!

[NoAffinity]

2) Yes, NTSC will be black and white on PAL TV's, and vice versa. Something to do with the subcarrier info/frequency I believe. Bigger brains can probably give the exact details.

3) RGB mod at the CD expansion. If doing it within the base unit, there will be no audio from CD's.

[thebigcheese]

I wouldn't really call that a soft mod. It's more of an attachment since it can be unplugged and no actual modifications were done (at least, I am assuming you can detach it). Regarding the issues you are having, it could be either the attachment or the cable, but the cable is where I would start. It's probably not fully shielded, so there's crosstalk between the lines causing interference. However, it's also possible that the attachment isn't very well designed and the traces are too close together, which would also cause interference.

The standard output of the CoreGrafx is just composite video, not component. There are only 5 leads on there, so that's video, left audio, right audio, +5v, ground (I believe). However, if you find that a new, fully-shielded cable doesn't eliminate the interference, an internal mod is pretty easy to do and requires no modification to the case. You simply replace the 5-pin DIN with an 8-pin DIN and solder a few wires. I've detailed the process with pictures for the CoreGrafx on my wiki: https://www.retromodwiki.com/wiki/PC_En ... od_Install. There's still a tiny smidge of interference on the video (generally not noticeable in actual use), but none on the audio. The benefit of this kind of mod is that you can still add on a CD attachment since the expansion port is free. You would then take video from the CoreGrafx and audio from the IFU. That does require a custom cable, but it's the only way to get stereo sound (you'd still get mono sound from the IFU without tapping audio directly from it). As NoAffinity mentioned, you can also mod the IFU, but that does require cutting and personally I'd rather do it at the CoreGrafx so that I can use it without the IFU and still get RGB.

[NoAffinity]

Thanks for correcting my audio mis-statement, TBC. And you had found the best way to route wires to eliminate noise/interference, if I recall (I even tried it out and confirmed it offered an improvement ). That is for the base unit only, though. Possibly also applicable to a CD add-on, but I know we were just testing on the base unit.

Assuming an add-on like below, could you not do the same 5-pin din to 8-pin din replacement with an internal amp, and get RGB with stereo out of the CD add-on?

Spoiler

[thebigcheese]

With that one, probably. The IFU (for the original CD ROM ROM, side note my favorite dumb name for a thing) just has RCA jacks, though, so you need to cut it to fit a DIN jack. I think I have also seen where people replaced the plastic plate the RCA jacks are attached to with a 3D-printed one that can fit the DIN jack, but don't quote me on that. I know there is a MLiG video out there where Try was having a lot of noise issues with his RGB-modded IFU. I believe Voultar eventually found a good way around that, but I don't believe those boards are for sale yet. Maybe he just put them on OSH Park? Can't remember, but that was one of the reasons I went with the CoreGrafx mod in the first place.

Also, keep in mind that an open circuit board like that can easily pick up interference from stray RF signals in the area, so just moving the console somewhere else might also help. This is the reason why the consoles have RF shielding in the first place.