What is this graphics issue

[L-Digital]

Hello everyone

What a great forum.

First post here, I wondered if anyone can help with this odd issue I am seeing on some games

I have an interface unit which has been rgb modded by otaku's store in France

I have 2 different PC engine units which both display this odd artefact issue where solid colours look slightly corrupted or something, very hard to explain. Both PC engines (white and core 1) display the same thing and it's very noticeable when scrolling left and right

I am running through a framemeister and no other machine snes Genesis Saturn do etc has this issue so I don't think it's my switch or upscaler



Is there anything I can do for this?

Thanks

[blueraven]

L-Digital,

Both of the game systems have the issue?

Before you open it up, have you tried a different AV cable?

[Vimtoman]

Are you using composite video or CSync to sync to?

[L-Digital]

I tried two different cables and it's the same result. These cables are crystal clear on my duo-r setup.

Both white and core grafx PC engines display the same issues through the interface which makes me think it's that.

The artefacts only appear in the top half of the screen, the bottom is clear. It's very distracting on horizontal scrolling sections

I checked on my duo-r and it's completely clean in comparison at the same parts of the same games.

I am also getting some diagonal noise which is really hard to get on camera when using my IF setup (see bottom right area of blue picture)

I believe sync is coming directly off one of the pins of the IF interface next to the rgb pins. I have a sync stripper that goes in to my framemeister so everything feeds through that. Is there another sync option that may fix it?

Here is the other diagonal issue

 

[L-Digital]

Edited op with a much clearer picture (sharpness turned up highlights the issue)

Issue affects the top 1/3 of the screen

[mickcris]

Have you tried a different power supply for the IFU. Sort of looks like noise from a cheap power supply.

[L-Digital]

Unfortunately I don't think it is that. It was one of the first things I thought.
I have tried replacement power supply and the original nec one via a step down convertor and it's the same issue

[Fidde_se]

I do have a weird answer for it which is rarely talked about today but it's quite important now when people aren't using CRTs to the same extent.

This is something that just not could happened to the PCE, you would not see this if you were using a CRT, yes if you could it would probably be a badly constructed power supply (or a fridge in the same outlet), anyhow you are using a Framemeister, and what it does is converting the analog signal it to digital, lets say that with other words, it's a digital interpretation of an analog signal, so what you see might actually not be what's actually there, this goes deep down in the calculations of the algorithms of how the scaling and processing is down, the blacks is especially known for this on the PCE on the Framemeister.

That's usually fixed with the Brightness control on the Framemeister, which sounds awkward since it does not seem to effect Brightness, the XRGB-3 had Blackness (黒レベル, Black level) and looks like this function so it might be a mistranslation somewhere, it's set at 27 as standard and 21 usually looks good, I don't know if this would effect the dark blue you're seeing but it effects the the same kind of disturbance you see in that but in black.

The best way to describe the misinterpretation problem is on the GBS-8200 playing SNES with Magical Quest, when mickey jumps the ground he stands on bounce with him a few pixels and compresses when he hits the ground again, it's obviously not happening in reality it's just Mickey that jumps... there's also like a gloria around him when walking that bends and distort the leafs surrounding him, not as obvious thou...

[L-Digital]

Thanks. I tried your advice and attempted to to tune it out using the black level. I was able to make it invisible at 35 but it completely changed how everything else looked which was no good. I did a bit of experimentation and tried the composite out, even with the framemeister and to dialled up to max sharpness the issue is not there, so I am certain now that the rgb mod is what is introducing this issue. Possibly a dodgy amp. I have taken a look and they glued the amp down so it will be a pain to remove, I am thinking if I can leave it there I'll get a different amp and try that. Are there any recommended ones? The one in my doijindance modded duo-r is handmade on breadboard but is crystal clear. I wouldn't be able to copy that

[thesteve]

its more likely wire routing/amp placement then an actual bad amp
it could be as simple as moving the amp or a wire 1/4"

[L-Digital]

They glued this sucker down I can't move it

I don't think there is a way to loosten this glue :/

Would the glue maybe cause this issue if it's being conductive in some way?

[thesteve]

amp location looks like it might have issues on cd games
i would try seperating the RGB input wires from the bundle and see if it helps
you could also try replacing them with shielded wires
that looks like hot glue, it can be melted by heating the area, but i wouldnt use an intense heat source and do it slowly

[mickcris]

if its hot glue, you can also put some Isopropyl alcohol on it and it will unstick

[L-Digital]

Ok I have completely ruled out the amp. I first swapped sync source from sync to composite and that had the same issue. I then completely bypassed the rgb lines to the socket and missed the amp. It made the colours go dark as hell but the problem remained. So I am at a total loss now what to try next after I have put everything back how it was

[thesteve]

could be on the ground pin of your mod as well