PCE Turbo Duo RGB - No jailbars - working solution

[NightWolve]

FYI, I've had a little guide for this based on Steve's last findings.

http://www.pcenginefx.com/forums/index.php?topic=13231.0



You've added 2 additional tasks of replacing en existing capacitor and adding a jumper wire for additional grounding. The tip of grounding your video circuit back to pins 55+56 is also another difference I see that you didn't try or know about. If there's further confirmation of what helps, I can update the photo some time but generally I just prefer going with Le Stevo's findings/research.

[thesteve]

i can confirm what he did was based on my findings

[SegaSonic91]

Because there is no pre-wired sync when connecting a DIN8 to an IFU, I am going to try pure SYNC first to see how it works on a few different TVs.  I will only be using it on RGB SCART TVs, and I know that some TVs will only use composite sync.  I am tempted to just cut the trace and link pin 44 directly to the sync pin on the DUOs because I have no need for composhite, but I may leave it incase I ever want to sell one.  OR I may add a switch as Keith suggested.  If the pure sync from the IFU is OK, that will make the descision harder.  Great info in this thread, thanks to you all!

[leonk]

Hey NightWolf, thanks for the pic. Couple of personal suggestions:

- those are ceramic capacitors. They have no polarity. Assigning +/- makes no sense. I would actually emphesize to purchase +/- 20% caps rather than than ones that go up to 80%
- ground is ground. There's no such thing as better ground than another one. If you had "different" grounds you'd have a potential difference. Bad things happen in circuit boards (shorts, fires, death)
I think the massive ground plain which the caps connect to now is sufficient.

Csync vs other syncs issues is not native to NEC consoles. Other RGB modded consoles have similar issues. The "fix" discussed in this thread simply puts the Duo on the same playing field as others. Whichever solution one uses for sync on other consoles should employ here as well.

Personally, I'm not a fan of taking functionality away. removing composite video makes no sense to me.  There is another solution. But will require custom cables:

- remove L/R audio from DIN
- add csync to new vacant pin
- add 3.5mm jack for stereo

You basically recreated a Sega Genesis Model 1. Audio (theoretically) will sound better as it will have its own seperate path rather than crammed in with everything else.

[SegaSonic91]

errrm, massive noob question...  When installing the ceramic caps on 41 and 43, does one scratch off the green masking to reveal copper to which the ceramic is soldered to?

[gojira1954]

Yep, really hard to solder to otherwise
I use a scapel to scrape it off but you can buy fibreglass pens which are the 'proper' tool...

[SegaSonic91]

Yep, really hard to solder to otherwise
I use a scapel to scrape it off but you can buy fibreglass pens which are the 'proper' tool...

Hahaha, thanks!

[sirhcman]

I have mu duo-r rgb modded and thesteve did a bunch of stuff but i still have jailbars. not sure if this would fix my problem or not? its most notable in blue colors. i am using two different son pvm models with mickcris' scart cable. no idea what rgb mod thesteve used on it though

[NightWolve]

- those are ceramic capacitors. They have no polarity. Assigning +/- makes no sense. I would actually emphesize to purchase +/- 20% caps rather than than ones that go up to 80%

In that photo, yes, but some people use tantalums or others which ARE polarized so the labeling is still provided for whatever capacitors you do have, polarized or not. Why would I take away the labeling just for the one case used there ? That would not make sense, more info is better and helpful for noobs starting out...

Steve has taught people plenty of times on the ease of ceramics, though they do get expensive going up from these ranges. I also have a mistrust of them since a prior digikey purchase. I bought four 100 uF capacitors for my SNES but all of them only measured 60 uF when tested. All the 10 uF ones I bought were good showing 9.X uF when tested. Steve thinks I just got a really bad batch that time. It does seem like they clock in lower usually compared to other types.

http://www.pcenginefx.com/forums/index.php?topic=13231.msg287992#msg287992

In the above photo in the link, polarized models are used.

- ground is ground. There's no such thing as better ground than another one. If you had "different" grounds you'd have a potential difference. Bad things happen in circuit boards (shorts, fires, death)
I think the massive ground plain which the caps connect to now is sufficient.

I have to check who made that finding. I'll see what Steve says about it.

errrm, massive noob question...  When installing the ceramic caps on 41 and 43, does one scratch off the green masking to reveal copper to which the ceramic is soldered to?

Yeah, that is a massive noob question. Of course, no bond or conductivity can occur if you don't.

Also, you can use tantalum capacitors if you have 'em, just mind the polarity in that case.

EDIT: On tapping ground from pins 55+56, that was a Steve recommendation and also is shown in an online RGB mod video.

http://www.pcenginefx.com/forums/index.php?topic=13231.msg301235#msg301235

Keith Courage once noted that ground from pins 55+56 made the jailbar situation worse for one of the models he was modding though. But Steve thinks the grounding was bad to the chip so that's an oddball case.

I can't agree with the statement, "Ground is ground. There's no such thing as better ground than another one." That'd be like saying the same thing about the best place to tap the +5V source which is the output leg of the regulator versus from the A/V output. Anywhere else, you're adding the resistance of the traces and causing a voltage drop. And as we know, tapping from the regulator leg solves the problem with those powered region mods when using flashcarts.

The same thing about resistance and interference or whatever else should apply on determining the best place to tap ground as it does for the +5V source in principle.

EDITx2: Also, ConHuevos solved jailbars on his model with 220 uF caps in parallel to .1 uF as it didn't work with 22 uF for him.

http://www.pcenginefx.com/forums/index.php?topic=13231.msg320288#msg320288


So, more things to try if the main suggestions don't help, FYI to others.

[thesteve]

on the ground case, remember that every wire, and every trace has both resistance and inductance
the resistance is negligible in most cases, but the inductance can play hell with square wave currents, such as any digital signal

[leonk]

I did this mod to my USA TG16.  It uses Tim Worthington's AV Driver as the RGB amp.  I added the 2 ceramic caps to pins 41/42 and pin 43.  I also replaced C142 with a 220uF cap.

The jailbars went from very visible (same as on Turbo Duo) down to 2-5% visible.  You need to look for them hard, but you'll find them.  Regular players will never see them during normal game play.  On Turbo Duo I simply can't find them in the same spots. 

[Keith Courage]

thanks for documenting leonk.  Has anyone tried these other places that Otaku store has for larger caps?:
http://www.otakus-store.net/en/content/6-guide-nec-rgb

wondering if those help

I just did this extra capacitor mod for a JP PC Engine DUO. It works great. No jail bars whatsoever now. Just installed the one larger cap in the picture. Website did not say the value of the capacitor but from the length/width of it I'm guessing that it's a 820UF or 1000UF cap. I haven't seen many lower value caps that are that tall and skinny.



Adding this 1000UF cap is the only thing I changed. Did not have to add the two 22uf caps nor did I have to do anything extra with grounding.

[NightWolve]

Oh wow, very good find, mickcris! That's a purty thorough mod guide, we should note it somewhere more permanent like say in one of the sticky threads, etc. The site offers cap kits and other guides in decent presentation too.

[mickcris]

thanks for documenting leonk.  Has anyone tried these other places that Otaku store has for larger caps?:
http://www.otakus-store.net/en/content/6-guide-nec-rgb

wondering if those help

I just did this extra capacitor mod for a JP PC Engine DUO. It works great. No jail bars whatsoever now. Just installed the one larger cap in the picture. Website did not say the value of the capacitor but from the length/width of it I'm guessing that it's a 820UF or 1000UF cap. I haven't seen many lower value caps that are that tall and skinny.



Adding this 1000UF cap is the only thing I changed. Did not have to add the two 22uf caps nor did I have to do anything extra with grounding.

thats the same place as one of viletim's fix caps go.  he had stated that a ceramic cap is needed though.  wondering if that large cap might work the same or better.  the small ceramic is probably easier to put in though.

[thesteve]

if anything the 1000uf is overkill
ceramics tend to have better response, but if anything the 1000uf aluminimum will do at least as well as 100uf of ceramic