Vertical lines (noise) mostly in green.

[SlightlyObsessed]

Hello everyone,

I'm not new to modding but new to PCE. Thanks to the help of these forums, Viletim (and google) I've pieced my way through a RGB mod to a IFU-30. Everything works minus a small issue... hopefully someone can point me in the right direction..

I'm getting strange vertical lines (noise) mostly on the green signal but a little in the red and blue lines too. It appears to be related to grounding. I tried connecting green directly to the SCART head and it gets WAY cleaner. But I can't really leave it that way . If I try grounding the SCART cable to different spots on the IFU it gets more/less noise depending on where I connect. Least noise is when grounding to the AV Driver which is where I grounded originally.

I've tried two different SCART cables and they both experiance the same issue but work fine on a duo-r that I have so I know the cables are good. Also, I have removed the audio lines from the SCART line to rule it out but no luck there. BTW I'm using the sync line next to blue on the ext connector.

Here's a breakdown of my setup:

Pc Engine (White case)
IFU-30
CD-ROM2
AV Driver (installed in IFU off ext connector)
Completed Tims jailbar fix with the included caps.
Connected to framemeister via SCART.

Any ideas or suggestions?

[SlightlyObsessed]

I've read a bunch of other posts and I've ordered a new power supply for the IFU which was suggested by mickcris. The interference is not snow like or wavey lines but more jailbar looking. However it's not the same as the jailbar images I've seen in other threads. These are very noticeable, fixed, thick bars which are evenly spaced roughly every 10 pixels or so.

I'm hoping it's the power supply but can't help but think grounding could be the cause since I can clean them up greatly by connecting green directly to the SCART pin 11 just before the framemeister. Has anyone had grounding issues with this setup before? Am I missing something simple somewhere? Also, I noticed a YouTube video with an open IFU and noticed a tin/aluminum shielding under the IFU. Mine is missing this barrier completely...

Appreciate any advise.

[SlightlyObsessed]

Links to images:

[mickcris]

What kind of connector are you using on the ifu for the scart cable?  Do you have ever the outer shield of it grounded?

[SlightlyObsessed]

I'm using the 8 pin din. The brown wire is running from the housing ground point to the SCART ground pin (pin 2) which runs on the black wire to the AV Driver's ground plane.

[mickcris]

Also try swapping the sync with composite video. Next to the red.


edit:
This person was also having issues with it but it doesnt appear to be the exact same thing
http://shmups.system11.org/viewtopic.php?f=6&t=58495


you could also try to hook it up to your pc engine and bypass the ifu to see if its any different.  you can use it that way if you get rgb from the console and sound from the ifu.  but you could just hook it up that way to test

[SlightlyObsessed]

I just tried moving my sync line from the sync connection (C22) over to composite (A22). Result was the lines were still visible and an overall uglier/wavey image. 240p test suite wouldn't launch after doing this for some reason (games worked however).

Unless I'm impatient I'll hold off trying the mod on the PCE directly until the power supply arrives, hopefully it won't come to that, but it's an option.

Few other things I thought may help.

I'm currently pulling power and ground off the ext connector (C21 and C20) for the AV Driver. Is there a better suggestion for 5v/ground within the IFU?
I'm not running 5v to the SCART cable since I don't need it to enable my display. I can't imagine this would resolve my issue but I thought I'd mention it.

[SlightlyObsessed]

Mickcris- Thanks for the feedback and the reference link... My issue is solved! Looking at a pinout of the ext connector the PCE has a GRDa (Analog) and GRDd (Digital). I moved power and ground over to different pins identified by RGB32E in the linked thread. I moved to pin A2 for power (this could have probably stayed where it was) and A21 for (analog) ground.

I remember reading about the grounds somewhere but the thread refreshed my memory. Before I tried this I tried power/ground from the IC and it made things much worse, reinforcing my suspicion of grounding issues. Not sure all the differences in the two grounds and/or if the AV Driver is more susceptible but I would suggest anyone with noise in there video lines try the GRDa connection.

Thanks again

[mickcris]

Maybe your pce is missing the ground shield.  It connects those on some white Pce systems.  Although I would think it would not have worked at all if that was the case

[SlightlyObsessed]

When you say PCE ground shield, you're referring to the soldered on tin/aluminum that coveres the entire bottom of the PCE PCB? Lol

If so, my PCE does have that and I resoldered it after doing Tim's jailbar fix.

However, as I mentioned above, my Interface Unit IS missing the shielding which should line the bottom. You can see it in it's proper home in this image:


It looks like there are several areas that connect to this missing shielding...

Think the digital ground should not have that interference in it to begin with?  Im sure the lack of IFU shielding isn't helping overall...I'd have to find a suitable replacement for it...least it looks great now anyway 

BTW- I ultimately did leave out the audio from my SCART cable since it introduced a bit of noise again when re adding it. I tried it two ways, one directly off the IFU and from the IFU to the AV Driver first. The AV Driver made it less noisy but it still wasn't ideal. It's easy enough to just connect the RCA jacks.

[mickcris]

It could be that ground shield in the ifu that caused it. 

The one on the pce is needed on some consoles.  They changed the layout at some point and some it does not connect those grounds and some it does.