MOD GUIDE - Universal RGB-to-YPbPr/Component Circuit & Mod (8/24/2014)

[Keith Courage]

turbokon, did you have to add the two 22uf caps for the jailbar fix or did it look good without them?

[turbokon]

I noticed the jail bars too especially on blue background. I added the two 22uf it only improve it slightly.

An update on my component mod, I used 500ohm for r2 and 3.8k for r4 and got brighter green and blue.

[EvilEvoIX]

Is this worth doing over a Quality S-Video job?

[turbokon]

The quality difference is quite noticeable so I say yes if you're good at this sort of thing. If not, I wouldn't bother with it, to much of a pain to build.

[turbokon]

I build another cleaner board and the red drops off after a few mins every time. It doesn't matter on how the 22uf's are polarize, it didn't help. Still waiting on my non-polarize caps.

[turbokon]

Looks like I got the component mod working right. I used 500ohm for R2 and 10kohm for R4 & R6 and everything else per thesteve design. With the pots I can adjust the red & blue to my liking. I've been at this for a few weeks. Time for me to close it up:)

[Keith Courage]

So, I finally did this mod on a system I had on hand and man do I have to say it is not for the faint of heart. It just took a really really really long time to build this circuit. It took me so long I have decided I will never do this mod again unless there are some premade PCBs for it cause it definitely was not worth the time to have the improved picture quality. Then again, I still prefer to use a CRT TV. So I suppose if all you own are Flat screens then maybe your will power to do this mod would be greater?

On the positive side it does look great.

[turbokon]

I finally got my TG16 all closed up with the component mod. All I can say it looks fantastic on an HDTV now:)

[Keith Courage]

I am having an issue with Jailbars. I installed the two suggested caps for the jailbar fix and it doesn't seem to do anything to help. The system I put the mod in is a US TG16. The games you can see them the most in is anything with blue background. So bomberman title screen or JJ and Jeff work great for testing. Anyone have any suggestions?

[NightWolve]

I am having an issue with Jailbars. ... Anyone have any suggestions?

I got two for ya:

1) From steve: Ground your mod video circuit (be it a RGB amp or our new YPbPr mixer, etc.) as close as possible to the 6260 chip - pins 55+56. You can bridge them as they're both ground for easy soldering of a wire! Here's a nice video I remembered that I'm gonna link in the OP:

I've also updated the Jailbar Guide photo to help.



2) You familiar with twisted pair wires ?? That was a basic, cheap way to help reduce interference as the ground/negative wire wraps around the signal wire, etc. The next step up, the better way was a coax design, where the ground is sheathed/braided wiring that completely surrounds the signal core wire inside. If they use aluminum wire, they'll even wrap it with solid aluminum foil. If it's just copper, it'll be just braided copper, etc. Anyhow, point is, if you're willing to do the grunt work, you can try switching from single, solid wires to dual ones that include ground, just like the very RCA cabling that is used for Composite/Component on the outside, etc. The best would be the thinnest copper ones you can find. Problem is they'll be bigger than the single wires you're using now... Solid twisted pair wires not so much, but they're not as good at interference reduction. Note, no guarantees here with this idea, but just a suggestion...

Other than that, I can't think of too much else from what I've read around here. There was talk about using more shielding over chips and stuff somewhere though. If you were willing to go that far, that is, etc... But yeah, I'd try the first basic suggestion unless you already tapped those pins for ground.

[Keith Courage]

I'll try taking ground directly from the 6260 Chip first and let you know what happens. Thanks for the info.

[Keith Courage]

Not sure how or why but using those pins for ground off of the HU6260 chip actually made my jail bars worse

[turbokon]

Keith, how did you tapped the rgb & synch for the tg16? The first tg16 I tapped from expansion bus and the jail bars wasn't that apparent. I just did another tg16 and I tapped it directly from hu6260 and jail bars are more noticeable.

[Keith Courage]

I tapped everything directly from the HU6260 chip. Maybe I should try the expansion bus instead.

[Keith Courage]

I just tapped from the expansion port instead and man what a difference. The Jail bars look 10 times better. They still exist but now you have to look for them instead of them staring you right in the face.

I still wish I could get them to go away completely but I guess this is better than the way it was. Still very noticeable on blue backgrounds.

Can anyone confirm that jail bars are not present on DUOs? Maybe it's a US Tg16 issue for whatever reason?

[turbokon]

That'a good news, I will redo this tg16 and tap rgb from
 Expansion port.

Yeah, the jail bar is eliminate with the fix for a duo, at least I didn't notice it.

[NightWolve]

I just tapped from the expansion port instead and man what a difference. The Jail bars look 10 times better. They still exist but now you have to look for them instead of them staring you right in the face.

I still wish I could get them to go away completely but I guess this is better than the way it was. Still very noticeable on blue backgrounds.

Can anyone confirm that jail bars are not present on DUOs? Maybe it's a US Tg16 issue for whatever reason?

Oh wow, thanks for the experimenting. Hmm, so tapping ground close to or at the chip is questionable then. I wonder if shielded wires like I mentioned would make a difference. That'd be the other thing left to try besides that shielding idea (those plastic coated pieces of aluminum or whatever they cover chips with, etc.).

So to review, with steve's 2 capacitor idea and tapping the signals at the expansion port, jailbar reduction is pretty good now ?? Is your +5 V supply taken right from the regulator BTW ??

[thesteve]

sounds like you may have a bad ground to the chip itself

[turbokon]

Is there a way to check whether you have a bad or good ground with a multi meter obviously other then the continuity check??

[Keith Courage]

If there is a bad ground on the chip itself couldn't I just take a wire from the ground on the board and run it to pin 55&56 to fix the problem?

[NightWolve]

Where you soldered the negative end of those 2 jailbar fix capacitors is the closest other ground point. Be interesting to see if that would make a difference.

[turbokon]

I just installed the component board in another turbo duo and can confirm the jail bar is eliminated with the jail fix. So the jail bars fix definitely works on the turbo duo but doesn't work so well on the turbografx systems.

[Keith Courage]

Meh, that's a bummer. I'll only suggest this for people with DUOs at the moment then. At least it works well with those. Personally the with the jail bars being put out by the Tg16 I modded I'd rather just use composite just so the jail bars don't exist.

[turbokon]

I change the placement of the component mod board, jump hu6260's pins 55 & 56 to the ground of the component board and jump from comp board to another ground. This is the best I've seen regarding the jail fix for the tg16. It's barely noticeable.

[turbokon]

Another thing, I see that pins 41 & 43 already have capacitors to ground on the duo so I switch to 33uf caps with the tg16. So it's safe to say with the combination of all these things drastically improved the jail bars.

[NightWolve]

Fine work, turbo! So steve's ideas are vindicated once again. ;) I wonder why things didn't work so well in Keith's attempt, though. I guess I'll just need a disclaimer on any Image Guides: "Your Mileage May Vary, etc."

[ConHuevos]

I'm going to be installing a BA6592F coupled with a 3 video channel amp in my duo as soon as my parts arrive within the next 2 weeks, I'll post my results.

In the mean time does anyone know if you can buy the AV connector plug for a turbo duo or do I need to change it to something like a mini din so I can make a component cable for this.

[Keith Courage]

Everyone here has their preferences. din 8 jack, VGA jack, RCA jacks. all work well.

[ConHuevos]

Ah, I just want something where I don't have to rip a hole in the system.  I want it to be able to go back to stock if I ever want to change it.

[thesteve]

i just built a board up to test/inspect turbokon's board
im very happy with the performance of the board as designed
i also built it using all 22uf ceramic caps instead of the 220uf and 470uf i originally spec'd
the test was connected to the expansion port on a white PCE

as for the AV din on the duo, the 8 pin din is easy to find and would work for the mod

[turbokon]

Yeah, I just got some din 8's in and will use this on the next duo I'll mod.

[turbokon]

Thesteve, it's about time you caught up with me:)

[Duo_R]

I assume the jail at fix with 22uf caps works on the Duo-R?

[thesteve]

yes i did it on a duo-r

[turbokon]

I just installed the component board in a turbo express. I can't get rid of the jail bars. I tried grounding the two caps to hu6260, shield and component board but got the same results each time.

[Duo_R]

I'll installing this coming week and post the results.

The one you did had a stock screen ya? Could be the RGB lines being shared with the stock screen.

I just installed the component board in a turbo express. I can't get rid of the jail bars. I tried grounding the two caps to hu6260, shield and component board but got the same results each time.

[turbokon]

No, it's modded with a 3.5"LCD. I tapping rgb directly from hu6260. I will see if I can tap rgb from else where.

[thesteve]

the TE has a noisy power supply, could be the cause

[turbokon]

Is there a way to reduce the noise?

[Duo_R]

I am sure some caps could help with that. Also is this one lithium battery?

[turbokon]

Yep, this is my original modded TE. I added both shields back and seem to help some but still not as good as the duo. It still beats composite video:)

[Keith Courage]

I finally got a chance to move the component board in my Tg16 to the place you mentioned turbokon(in your pic). It definitely helped with the jail bars. It's not perfect but definitely an improvement. I'm happy with the results.

[turbokon]

Yeah, in my experience, the jail bar fix works best on the duo. I have installed the component board in the duo, TG dock, TG-16, pc-engine and a turbo express. I still need to install the component board in my pce-lt and supergrafx.

[turbokon]

I just installed a board in my pce I had thesteve worked on and it looks great. I didn't have to install the two caps for the jail bars fix as there weren't any. First system I didn't have to do the jail bar fixs.

[Keith Courage]

Hmmm, so it works perfect with no jail bars on a white PCE but not on a US TG16. weird.

Nevertheless good to know.

[turbokon]

No, just seem to be this particular pce only. I did another pce and I couldn't get rid of the jail bars. The only thing I did differently to this pce is that I replaced the three ram chip a while back, the one by the hucard slot and two on the main motherboard. I don't know if replacing these ic's affects the jail bars or not.

[thesteve]

it couldnt be the ram
i just did a CG RGB mod that didnt need the jailbar fix right after fixing turbokon's PCE

[ConHuevos]

My BA6592F's finally got through customs....only to find out I don't have enough rca jacks now >_>.  Need to wait for those to arrive before I can play with this.

[ConHuevos]

Anyone know the impedance for the RGB lines coming off the 6260 by chance?

[thesteve]

they carry 1K loads easy