shmups.system11.org

https://console5.com/wiki/Hu6260#Jailba ... al_Bar_Fix

SuperGrafx
Replace C168, C169

Hi guys,

hate to necro a thread this old, but it looks to be the most pertinent as the PCE and CoreGrafx seem to be their own beasts vs Duo.

I had my US TurboDuo recapped with the jailbar fix applied. Here's what it looks like through the OSSC, LPF 9MHz.



My modder messed up and accidentally wired it for composite video sync when I'd asked for CSYNC but he's being really good about handling shipping both ways to fix it. He said there's the possibility something happened in transit to account for those jailbars, but insists they weren't visible on his monitors. He wants to prove to me they aren't visible on his monitors...but that doesn't really do me any good if they're still visible on mine.

I see threads where people have managed to completely rid PCEs of jailbars and provide pictures, but not a lot of Duos.

What could be causing this? Is there something to be tried beyond what was applied?




I should add I'm using a Retro Access RGB cable.

That amp PCB doesnt have space to buffer Csync, the 4th channel is unused.
If you sent it to him expecting to be able to get csync then its your fault. I wouldnt be running straight from the Hu.

Probably not the best idea running RGB inputs under a Hus legs either, sure it looks neat and fancy but its just asking for crap to couple into the video before being amped.

With the jailbar fix, i have seen some work and some not, mostly from the position of the caps. I tend to follow the positions on Console5 https://console5.com/wiki/Hu6260

I have just fit these caps on my brothers system which is the same model as yours, but im yet to go there and see if the bars are gone. It was noticeable on his crt on black screens.

He offered CSYNC and he provided the board. It's an error he made and was upfront about it once realizing what happened.

If you wouldn't run from the Hu, what would you do, and what benefit might I see? These jailbars are really bumming me out.

Did you mean your brother's unit was *not* noticeable in dark screens? The way you've worded it, I'm not sure why you'd need to see it in person if he's reporting still seeing bars...

I went to his place and noticed it straight away and offered the fix.
Im keen to see with my own eyes the difference as he never gave me his scart cable to test here.

When I said dont run straight from the Hu I meant buffer the sync somehow, maybe with he unused channel on the amp, or an amp pcb built for 4 channels

If it were me, I'd just not run the black wiring underneath the pins of those Hudson branded chips. Although it doesn't look as neat, it's better to not tack the wiring down to the PCB, not routed through a row of chip legs, etc. because it's all potential noise.

I also wouldn't have a long ream of unshielded signal output wire stuck down like that, over the audio output circuitry no less, but that's just me.

Going with composite video over c-sync is not the end of the world at least, if anything it's at least 75 ohm attenuated if it's being pulled from the stock video-out point, which it appears to be. Can't say with absolute certainty if this is the case with the Turbo Duo but on the Turbografx c-sync is supplied to the expansion bus without any protection circuitry right from the source chip (Hu6260). You do NOT want to hook that up directly to anything, it has to be conditioned and amplified. For the TG16, composite video at least has a few resistors and transistors in between output and the source chip, so that's my default go-to for sync on that system.

Is the location for the amplifier PCB the recommended one?
I just wonder if it's a good idea to place it there:
- in the middle of busy data lines
- further away from the RGB source than seems necessary

Why not place it near the HU6260, right where that huge ground'y area is?
Also, and this goes with that decision, it is okay to use Vcc and ground from islands within the busy data line area?

Thanks for the input guys. Does anyone have any pics they can share of Duo mods that don't exhibit jailbars? It's difficult because my modder says he doesn't see them on his end.

Short of shipping him my Duo, my OSSC, my SCART cable and my LCD, it's going to be difficult to troubleshoot and adjust the install if we're not seeing the same thing...which i honestly don't understand. I would think a test rig should include an unforgiving monitor. Or maybe mine's just far more unforgiving than his?

My modder came highly recommended and many people are happy with his work. I'm just trying to solicit suggestions we might try together--a list of best practices (or perhaps more recently discovered best practices?) we can follow to kill these jailbars dead. I just want to be clear I'm not trying to step on toes and I don't think providing feedback in this thread will be viewed as such.

There are many ways to skin a cat--this particular skinning didn't work out with my combination of gear so I suspect it's time to try a different approach.



The signal has to pass through an extron crosspoint, so I'm under the impression CSYNC will be a necessity...

No, that's fair, the Crosspoint requires a clean sync signal, and certainly some monitors. I'd assumed if it was going strictly into the OSSC and some other switching setup like a gscart, composite video would have been fine.

I have some RGBS bypass boards that can be used on any and every system, Just have to change resistors or caps to suit each console.
I intend on fitting one to this model soon and ill update with amp placement.

Oh that would be awesome. Maybe I'll hold off on shipping it back until I get your feedback...

A few questions...

Where did you purchase your OSSC from? What type of power supply are you using with it and also your console?

I was part of the initial pre-order. I have the unit without audio. I'm using the Power Supply it came with, and for the Duo I'm using the original NEC power supply.



Just to rule out the OSSC I've taken more pics of other consoles:

Turbo Duo with the worst jailbars



JVC X'Eye with lesser jailbars (only visible in black - sonic blue is fine for example)



US Launch SNES that's blurry - bars, if there, don't bother me



US Saturn Model 1 - clean clean clean. If you see anything it's imugr's doing



Oh, and that LCD's colours/contrast look insane at an angle.

I wonder if any of this would work for the SNES.

I have the exact same jailbars but they are Horizontal instead.

I'd be interested to see a picture of that.

A major difference between horizontal and vertical jailbars is the frequency of the interference in the signal. For vertical jailbars you're probably looking at something over 100kHz, while horizontal bar interference probably under 10kHz. If they're fat enough, they could even be under 1kHz.

The ceramic capacitor fix for the PCE works by addressing high frequency noise inside the system. These same capacitors would be ineffective for low frequencies.

Honestly, horizontal interference sounds like a problem with the cabling, or possibly with the power supply. Supposing that the problem is inside the system, I would suspect either electrolytic capacitors or the 7805 voltage regulator going bad. In that case, you'd just have to replace them.

Did you ever make it over to your brother's place to see if the fix worked?

Oh yeah his console looked perfect.
The board I ended up using is ugly, I was scraping the bottom of my parts bin, but its pretty much what Voultar uses for Turbo-Duo. I used 1.8K resistors I think his board has 1.9k or 2k. Buffered csync.
I used a heavier gauge wire than usual to try minimise noise pickup.
Fit the bypass caps in the places pictured on Console5
I fit a new drive at the same time which fixed audio skipping issues he was having.