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

[NightWolve]

I gather Steves set is suffering from some major lag there due to the difference in character animation taking place between the two tv sets. Lag looks to be significant too. But anyway, these shots with the phone camera are way too shity to make any good judgement calls on quality here. I'd rather stay reserved until work is finalized on the mod and someone with a decent camera can take some shots.

Eh, false alarm... Littl' bit of mis-communication with steve on this - figures, I bolded the question I was curious about (RGB v. YPbPr) but looks he mixed it with my suggestion to him about checking the Composite signal to make sure he's getting the color levels (and tint) right and what not.

steve, when I suggested a Composite comparison against the YPbPr output, that was meant for you, to help you make sure that the color levels just about match with the Composite output as well as the tint (on the same TV)! That's how I tweaked my SNES YPbPr mod: I would quickly switch from Composite, to S-Video and back to YPbPr output and try to get the color intensity to match just about. But yeah, I would suspect tint also might be an issue in your case. Kind of a no brainer, you probably already have been doing that, but it was just FYI.

As for the RGB v. YPbPr comparison, I wanted to get an idea of how much better analog RGB is compared to analog YPbPr in the case of a console, etc. I've corrected the labeling on the images above and of course they make sense now, seeing that YPbPr is far superior than Composite wasn't an unexpected result. I was more curious about how much better analog RGB is compared to YPbPr in this case. That's all. I was confused, I didn't think they differed by that much, but the shitty image was Composite all along... Anyway, carry on.

[thesteve]

in my case RGB will be far superior, as my set supports 240P in RGB.
that difference wont be so noted on sets that do 240P component

[ConHuevos]

Any updates on this?

[thesteve]

i need someone to build from the schematic for verification

[NightWolve]

Any updates on this?

Yeah, go ahead and build the schematic shown on the first post if you're feeling adventurous and wanna help the cause. ;) Steve and BlueBMV have a partnership to build pre-made PCBs eventually based on that schematic (with RGB and S-Video support also I believe) to make it easy for everyone (you'd mainly just have to solder wires to the Luma, RGB and Sync pins, Composite, +5V, Ground, etc. and then to the RCA/S-Video outputs), but steve wants some more verification by others to manually build what's there before taking that final step. It was implemented on 8bit4Life's (a customer of steve's) Turbo Duo so far with success.

i need someone to build from the schematic for verification

Sorry steve, I still gotta do a full capacitor replacement first on my Turbo Duo motherboard (I want it 100% restored before doing the mods along with plans for videos) and I just have been doing other things lately (SNES) along with other distractions and downtime, etc., so I don't wanna hold you up with your plans for manufacturing boards. I think the only tweak I could help you with is determining the best output resistance value for Luma instead of having to use a potentiometer, but maybe you like having a pot there better anyhow. I assume Blue was going to build it manually as well, no? Anyway, I'll see what happens; it's *ON* my To-Do list no doubt, it's just my energy levels, interest, enthusiasm, mood, etc. change over time. You know how it is.

[Game-Tech.US]

you'd mainly just have to solder wires to the Luma, RGB and Sync pins, Composite, +5V, Ground, etc. and then to the RCA/S-Video outputs

I just tried this and got nothing, I did have a 3904 in backward at first and one jumper missing, but all I get is black screen.
I see no place for luma, composite, or +5v in to this circuit or svid out, did I miss some things or did you list the extra stuff for no reason? ;)
I assume sync is used for S input, but a few posts in NW is talking about how it uses Y(luma) another mistake on the schematic or what?
Can I also assume it's ok to pull rgb straight from the 6260?
Where do you pull sync (or luma)?
I'm trying this on a Duo.

[NightWolve]

you'd mainly just have to solder wires to the Luma, RGB and Sync pins, Composite, +5V, Ground, etc. and then to the RCA/S-Video outputs ...

I see no place for luma, composite, or +5v in to this circuit or svid out, did I miss some things or did you list the extra stuff for no reason? ;) I assume sync is used for S input, but a few posts in NW is talking about how it uses Y(luma) another mistake on the schematic or what? Where do you pull sync (or luma)?

You misread that paragraph and confused that comment with the separate Component circuit in the schematic. I wouldn't list stuff for no reason... I simply mentioned future plans that steve/BMV have which is to manufacture and sell their own video boards (like JROK). Such a pre-made board would have it *all*, multiple video outputs: S-Video, RGB, and Component and all you'd have to do is solder the input end and the output end, etc. Such a board would use the natively produced Luma (pin 40) for the S-Video aspect, hence why I mentioned it. Why did I mention anything about it at all ?? To let people know a pretty cool idea is in the works, etc.

Can I also assume it's ok to pull rgb straight from the 6260?

Never done a RGB amp mod for a customer ?? I don't think you can tap them from anywhere else (never seen any mod where they weren't tapped from the pins of the chip) cause they're not actually used by the system elsewhere I read (The chip produces Y, R-Y, B-Y and CB to mix for a Composite amp and that leaves the chip). Well, here:

RGB + H/V Sync taps from 6260 Video Encoder Chip
	Yellow is for H/V Sync, RGB pins are color matched. Exact: pin 51 - Blue pin 49 - Red pin 47 - Green pin 44 - H/V Sync

So, you got 4 signal inputs going into this Component circuit and +5V (plus ground) for you to decide wherever to tap. Steve didn't make his schematic very detailed, but the +5V goes into the power line the transistors are sharing. I just made a quick redo:

Lastest:

I just tried this and got nothing, I did have a 3904 in backward at first and one jumper missing, but all I get is black screen.

I would replace that transistor. Assume it's been damaged to avoid complications in building this.

Anyhow, good luck!

[Game-Tech.US]

Never done a RGB amp mod for a customer ??

You may not believe it, but NO, never have actually gotten a customer to say yes lets do any video mod requiring rgb to start with, so far just adding composite and stereo jacks to the rear is as far as i've been asked to go, but I really want to sell what consoles I have with component outs.

So, you got 4 signal inputs going into this Component circuit and +5V (plus ground) for you to decide wherever to tap. Steve didn't make his schematic very detailed, but the +5V goes into the power line the transistors are sharing. I just made a quick redo:

Holy crap! Why would you show gnd but not +5V!?!? LOL
Glad I asked about it! I almost was sure there had to be +5V somewhere...
Anyway, thanks a bunch for clearing up some stuff for me, you've been super helpful.
I'll go back at it today/tonight and report back as soon as I know anything.

[Game-Tech.US]

Here's some video of what i've got, it's way too dark and maybe too heavy on green.
Can you tell me what voltages I should see from signal to gnd on rgb in's, and Y, Pb, and Pr outs?

[Bernie]

Ok, I have video, but it's way too dark and maybe too heavy on green.
Can you tell me what voltages I should see from signal to gnd on rgb in's, and Y, Pb, and Pr outs?

I cant tell you what is what, but I hope yall get this figured out. 

[NightWolve]

Ok, I have video, but it's way too dark and maybe too heavy on green.
Can you tell me what voltages I should see from signal to gnd on rgb in's, and Y, Pb, and Pr outs?

The RGB input pins are high actually, at 4.66 V according to steve. A really good circuit will kill that all off by the end of it to where you read 0 volts on the output. Industry specs call for 0 to 950 millivolts on Component or general signal outputs (like Composite, S-Video, etc.). You can get away with 1-2 volts though on the outputs (I got a BluRay player that goes 2.66 V max on its Luma line), but if it's 3+ or more, that's borderline bad, not good for the 75 Ohm impedance resistors on the TV/monitor's input module in my opinion (but that's what they're there for, protection), so you'd need pull down resistance and/or output capacitors.

Anyway, that's not an issue for now. See my comments on your youtube video for possible issues other than just reviewing the whole circuit again. Gonna PM steve to chime in on this also, if he hasn't seen it already.

[Game-Tech.US]

I get 435mV on Y,
2.25 V on Pb,
2.4 V on Pr.

[thesteve]

your Y is low
what is R16 set to?

[Game-Tech.US]

Ok, yeah removing r16 got the brightness right! Getting real close!
I still think blue is wrong, dark green is almost black.
Y is now 935mV, others unchanged.

[Game-Tech.US]

Also seeing vertical bars, very undefined. I usually don't see bars in component so i'm sure it's not the tv this time, I almost always see jailbars with composite and svid on this tv.

[thesteve]

if you need more trim r11, r12

[thesteve]

also the bars are native to the system, solved by 2 caps

awhile i figured out a jailbar fix, but was waiting for further testing
the fix is placing a 22uf ceramic or tantalum cap from the HUc6260 pin 41 to ground, and another from pin 43 to ground.

[NightWolve]

Yeah, good idea to mention this; steve recommends that while one is doing this mod, that you might as well add the jail bar fix that he came up with which turns out is purty simple.

You need two 22 uF capacitors for it (16V rated or better). Solder one to pin 41 and ground, and the other to pin 43 and ground (negative ends to ground obviously if caps are polarized). They happen to be right near where the RGB and Sync pins are tapped, so might as well do it right after. Since the 6260 chip is on the bottom side of a US Turbo Duo, those small surface mount caps would work best in that case, see his 2nd photo here. Japanese units with the 6260 chip on top are much more convenient to work with and using leaded caps would be easier, obviously:



Made this nice one just now, close up, bottom of a Duo:



OG Clean:

[Game-Tech.US]

I don't have any 22uF smd caps on hand, but good to know it's an easy fix....

[Game-Tech.US]

if you need more trim r11, r12

It doesn't need any more brightness, but trimming r11 down does make it brighter or wash it out is more like it, trimming down r12 makes it darker, trimming up washes it out just like with r11.
Well post more video in a minute.

[Game-Tech.US]

Vid showing dark green issue.

[thesteve]

r9 will effect green, but will change brightness as well

[thesteve]

r7 and r8 are green mix

[Game-Tech.US]

I won't say they didn't do anything, but none made dark green look right, still black...

[thesteve]

the green input resistor should effect green contrast, the sync input should effect all contrast

[Game-Tech.US]

Been at it for over an hour...
I have what I think is a great image, but I had to mess with everything to get it.
I also checked to make sure I had good connections at the 6260 from the pin and I mean right at the plastic to the circuit, all 0 Ohm, so that's good.
R2 - 75 Ohm - lower would lighten the still too dark green but top of image starts to tear right, some still seem too bright a shade of green
R16 - 47 Ohm - made a lot of difference putting this back in
R9 - 355 Ohm
R6 - 4.76k Ohm
R7 - 9.25k Ohm
R8 - 4k Ohm
R4 - 1.2kOhm

Does that make any sense? Is it just my TV?
Too be honest it's too sharp!
The colors don't blend together like composite so it looks weird, but I guess that's the compromise...

[thesteve]

lower r2 strengthens green, and weakens sync, thus the tearing (lower r1 would solve)
r16 reduces luma and luma offset (add cap across (470uf) to reinforce if needed)

[thesteve]

r6 and r7 cancel each other, as do r4 and r8

[thesteve]

try this
add 470uf cap across r16 47ohm
r4 and r6 5.6K
r7, r8 12K
r3, r5 2K
all others per schematic

based on the values you posted

[Todd Gill]

You need two 22 uF capacitors for it (16V rated or better). Solder one to pin 41 and ground, and the other to pin 43 and ground (negative ends to ground obviously if caps are polarized). They happen to be right near where the RGB and Sync pins are tapped, so might as well do it right after. Since the 6260 chip is on the bottom side of a US Turbo Duo, those small surface mount caps would work best in that case, see his 2nd photo here.

Would regular polarized aluminum caps be ok, or is a ceramic or tantalum cap really the best choice?

[NightWolve]

Yeah, any cap would work, from my understanding, but if your 6260 chip is on the bottom of the PCB (a US Duo), an aluminum cap will likely be too big when you put that PCB back in place. If you got a Japanese unit and the 6260 chip is on the top, like that first screenshot, then no problem. Ceramic/Tants are the better choice though, and the ceramic won't care about polarity, but they will be more expensive (ceramics >10uF stop being cheap). I noticed that Hudson/NEC used expensive tantalums on the bottom of the PCB and the cheaper SMD aluminums on the top (for the big uF values, of course you had to, as they only came in aluminum, so that had to be designed with space in mind, meaning they had to go topside).

[Todd Gill]

Yep, JP Duo-R.

I might have to give this a go this weekend.

Already replaced C961 with a 220uf per thesteve and that made a slight improvement to the jailbars.

[thesteve]

aluminum caps would likely need to be bigger

[Todd Gill]

aluminum caps would likely need to be bigger

I picked up some 22uF Tantalums from my local supplier.

[thesteve]

side note
looks like the schematic runs as drawn
just needs some resistor values tweeked (ready for PCB)
may need a resistor and cap at each output jack to reduce dc offset (off board)

[Todd Gill]

Finally had a chance to install the 22uF Tants for the jailbar fix.

Works great!

If there are jailbars there now, it's damn hard to tell.

[NightWolve]

Were you getting jailbars with S-Video or a RGB connection ?? Anyway, that's awesome! Supposedly, this is only a problem when tapping RGB, but just checking.

Good work steve, you mad genius!! How the hell this guy took risks with a video chip like that by fiddling around to figure this out I'll never know!

[thesteve]

didnt risk a thing

[Todd Gill]

Were you getting jailbars with S-Video or a RGB connection ?? Anyway, that's awesome! Supposedly, this is only a problem when tapping RGB, but just checking.

RGB. I see some very, very faint ones under some specific situations, but it's vastly improved.


Yes, thanks Steve for the great fix!!!

[turbokon]

I just started building this pcb. Still waiting for a few components to come in.

[Keith Courage]

Well poopy crappy poop. Looks like I am one type of resister short. Gonna have to wait a few more days to get them in the mail now.

[turbokon]

My HDTV also accepts RGB via VGA. I will do both YPrPb and RGB mods and do a comparisons.

[turbokon]

I couldn't wait for the 22uf tantalum caps to come in so I built the circuit using 22uf polarize caps instead. I get flickers between light and dark and sometime TV screen goes blank. I don't know if its due to the polarize caps or something else. Still looks better than s-video.

[NightWolve]

I couldn't wait for the 22uf tantalum caps to come in so I built the circuit using 22uf polarize caps instead. I get flickers between light and dark and sometime TV screen goes blank. I don't know if its due to the polarize caps or something else. Still looks better than s-video.

Hm, I see a green decoding issue there, I guess related to this flicker you say you're getting. I'd guess that would be mostly a problem with the Luma signal. The + side of the caps should be facing towards the +5V source after the 500 Ohm resistor I should think (steve??) - should've made that clearer in steve's schematic last time I updated it... Note: tantalum caps are still polarized, you'll still have to watch that. You're thinking of ceramics. Thanks for testing BTW! =)

[turbokon]

Colors looks good to me. I'm using an iPhone to record the video so that's might what you're seeing regarding the green. I will play around with the polarity of the caps to see if it helps any.

[turbokon]

At first I had the two 22uf caps polarity with the plus toward the 500ohm and now I have the minus toward the 500ohm.  It flicker from too red and then too green and sometime it goes blank and sometime the picture is perfect.

[turbokon]

I found some loose connection and now the flickering is gone but more red push thru every now and then.

[turbokon]

No more flickering,  everything is constant but now it's a tad dark and a tad green.

[EvilEvoIX]

I must say the s-video from console is a force to reckon with it's the best looking built in s-video.

I would argue that the Neo Geo CD unit is amazing.  Almost justify s owning one alone.

[turbokon]

I bypass r16 and got brighter picture but color are still dark compared to composite.

Component

Composite