Help with the RGB Amp (mickcris) - PC Engine Duo

farankoshan · 07/30/2015, 10:14 PM

I picked up an RGB amp + 8Pin DIN + SCART cable from mickcris and needed some help with it. I'm pretty convinced that mickcris sells exceptionally well made stuff, so I'm assuming the problem may be on my end.

So I followed the standard procedure and tapped RGB from the HuC6260 chip, wired the signal through the provided RGB amp, and coursed the signal through to the 8Pin DIN I also got from mickcris. (See below)

The signal comes through, but these are my problems:

INTERFERENCE: there seems to be a bit of scrolling interference. Like snowy waves scrolling up and down. I'm using a switching generic power adaptor that outputs 9v, and I'm aware that the PAD-124 (official NEC power supply) needed 10v. I just ordered a PAD-124 and when it arrives, i can check back to be sure. But does anyone know if there may be another fix besides the power supply? Anyone had a similar problem?

GHOSTING: There also seems to be some problems with the integrity and clarity of the pixels? I also have a SEGA MD/Genesis which outputs in RGB, and comparing both MD & PCE Duo seems like night and day. Let me first say that I know that composite is much worse and the signal I get from RGB is much cleaner, so I'm not being ungrateful for this newfound clarity - RGB is amazing. But what I get on the Sega MD is pixel-perfect sharpness and incredible clarity, nearly like playing on an emulator into a monitor. The PCE Duo seems "ghostier" and I want to know if it's that: 1. The PCE's image processing for RGB isn't as good as the MD; 2. Are there capacitors on the board that need to be replaced (I already did a cap replacement on many of these old caps)?; 3. Could it be something with the components from mickcris?

SCART CABLE PROBLEMS: So I followed the photos and instructions given by mickcris and wired the right pins as properly as I could, but for some reason the SCART cable I got from mickcris doesn't work. I used another SCART cable I purchase from an eBay seller (retro_console_accessories) who provided me with my Sega MD/Genesis SCART cable. That cable works, and so I assume that the RGB pinout aligns with mickcris' pinout in his instructions. Sound and image both come out fine (with the noise interference of course). But it seems like the SCART cable from mickcris won't work. I followed his B-G-R label (see the 1st photo) from the instructions, so it's strange that another seller's SCART works, but his doesn't. Any help with possible differences in RGB 8pin DIN layout?

Any help would be most appreciated. Mickcris has been very helpful thus far, and he is a trusted member of this community. He advised me to post it here to get a discussion going and possibly find out where the problem lies through discussion. Thanks, everyone!!

mickcris · 07/30/2015, 10:24 PM

I was wondering what RGB upscaler are you using? Is it possible your other cables are wired for JP21? Really the only thing I can think of as to why the cable isnt working.

Also like i suggested, you should install the ground pins on the DIN jack if you still have the old DIN5 port. Not sure if its the issue, but it would be better if they were there.

SephirothTNH · 07/30/2015, 10:36 PM

You could try tapping 5v from somewhere else. I've had to change 5v sources in the occasional mod to clean up video.

farankoshan · 07/30/2015, 10:36 PM

Quote from: mickcris on 07/30/2015, 10:24 PMI was wondering what RGB upscaler are you using? Is it possible your other cables are wired for JP21? Really the only thing I can think of as to why the cable isnt working.

Also like i suggested, you should install the ground pins on the DIN jack if you still have the old DIN5 port. Not sure if its the issue, but it would be better if they were there.

You're right, I needed the SCART to be wired JP21, since I pass it through a framemeister. So that solves the last issue on my list. My bad, I probably should've requested for a JP21 wired SCART. I assumed that all SCART RGB cables are created equal. Well, I have an extra cable right here then. (If anyone wants it, it's unused and I can ship it over at cost+shipping). Happy to have cleared that matter, mickcris!

Regarding the metal ground pins, does anyone here have a step-by-step with photos? I'm not very good with these things (it's amazing I even got a signal out of this mod. Woohoo!) And is there a "less drastic way" to do it? I remember there being another way that involves putting the 8pin DIN on it's side and wiring the pins to the back. I don't have a drill and would much rather keep the board as close to the way it is as possible.

Any help?

farankoshan · 07/30/2015, 10:38 PM

Quote from: SephirothTNH on 07/30/2015, 10:36 PMYou could try tapping 5v from somewhere else. I've had to change 5v sources in the occasional mod to clean up video.

(Looking at the first photo) By 5v, you mean somewhere else besides tapping it from the D4364G-12L chip? Any suggestions?

SephirothTNH · 07/30/2015, 10:42 PM

Not sure the photo is a little blurry but that sounds like the chip. Get a multimeter one of those caps should have 5v on the + side. Or the output of the 7805.

mickcris · 07/30/2015, 10:48 PM

here is the easy way to do the ground pins if you still have the DIN5 jack that you removed:

start at 2:00 as it wont let me put the link in there like that.

farankoshan · 07/30/2015, 11:01 PM

Quote from: mickcris on 07/30/2015, 10:48 PMhere is the easy way to do the ground pins if you still have the DIN5 jack that you removed:
start at 2:00 as it wont let me put the link in there like that.

The cutting of the tiptoes explains using the DIN5 cover on the 8pin DIN. But will I still use the metal thingy that you sent with the pack?

mickcris · 07/30/2015, 11:06 PM

you just need the ground pin part from the DIN5 jack. You can either just put those pins in the bottom piece or use the whole bottom part from the DIN5 jack. The bottom plastic part is the same on both jacks.

the one i sent with the jack is the one you would have to drill holes for as its different. For some reason the ground pin layout is different on those jacks.

farankoshan · 07/30/2015, 11:10 PM

Quote from: mickcris on 07/30/2015, 11:06 PMyes. i already cut the "tiptoes". you just need the ground pin part from the DIN5 jack. You can either just put those pins in the bottom piece or use the whole bottom part from the DIN5 jack. The bottom plastic part is the same on both jacks.

the one i sent with the jack is the one you would have to drill holes for as its different.

I see. Okay, so just to be clear, if I swap out the bottom plastic part (plastic part from 5pin DIN, to be put on the 8pin DIN) I don't need the metal thingy, nor do I need to drill holes anymore?

mickcris · 07/30/2015, 11:11 PM

you need the metal part from the din5 jack. you can use the plastic piece from either one.

thesteve · 07/30/2015, 11:34 PM

the noise is a ground discrepancy
you need to jump from the din ground to the board ground
dont know why your getting bleed

farankoshan · 07/31/2015, 01:35 AM

Quote from: mickcris on 07/30/2015, 11:11 PMyou need the metal part from the din5 jack. you can use the plastic piece from either one.

Got it. Will remove the plastic cover (with metal part) from the 5pin DIN, and transfer it over to the 8pin.

Will report back with results.

farankoshan · 07/31/2015, 01:36 AM

Quote from: thesteve on 07/30/2015, 11:34 PMthe noise is a ground discrepancy
you need to jump from the din ground to the board ground
dont know why your getting bleed

Hey thesteve!

What do you mean "jump from"? Sorry. Perpetual circuit noob here. :p

Does my photo do enough justice to show why there is a bleed?

wilykat · 07/31/2015, 02:22 AM

What he means is that the plug needs ground connection. The ground shell on video cable has to connect to the ground of the system to reduce interference. If the ground pin on the DIN connector is not connected, then you will get interference.

thesteve · 07/31/2015, 03:08 AM

the 3 coils behind the DIN are a big noise problem, because your signal ground runs through them
1 pin (not the shell) is your signal ground and will need a direct ground connection

farankoshan · 08/04/2015, 12:49 AM

I did as all of you suggested and BOOM... true, unadulterated, clear & crisp RGB! The sound comes through clear and the pixels have ZERO bleeding. ;)

It appears that not grounding the 8pin DIN through the two extra holes & soldering them down makes a world of difference. Aside from the 5 main pins on the 8pin DIN, those 2 extra pins (which I took from the 5pin DIN, and swapped them onto the 8pin DIN) instantly cleaned up the picture and created no problems in the visual department.

I'm not too good with circuitry (my friend solders and we work together) but thanks to this discussion, I got my results and who knows? Maybe there may be another person who ends up as lost as me and may need to find this thread to lead the way to clearer gaming!

Thanks for all your help, everyone! I booted up Parodius Da! this morning and couldn't believe how much detail I missed simply using composite signals.

The PCE is new again!

mickcris · 08/04/2015, 02:09 AM

Glad you were able to get it working.

Xenogears · 08/05/2015, 02:45 AM

Your Bleed-Problem is simple to solve: inside the DIN-Port there is a tiny metal nose for shield. If it is not connected, you get a Ground Ecco. Just add Ground to the Shield, and the Fade is gone. This only occurs if you use a shielded RGB-Cable and shield is not connected (one end at the scart Plug the other one to the DIN-Plug) and finally good contact to the nose in the DIN-Port...