New Coleco RGB board?

[+KylJoy]

3 minutes ago, MrPix said:

"...what RGB socket to people most want to use?"

I like using 8-pin mini-DINs wired like the xRGB-mini.

[+videofx]

2 minutes ago, MrPix said:

We can. Just remember the output is old school RGB, not VGA, and most newer VGA monitors won't be able to display it.

I want to connect it VGA to my OSSC  then HDMI out

[MrPix]

1 minute ago, KylJoy said:

I like using 8-pin mini-DINs wired like the xRGB-mini.

My standard S-Video board has 4-pin mini-DIN for S-Video, composite RCA, and next to that an 8-pin mini-DIN with that exact pin-out.

I'd also be able to supply the board unwired so people can do *whatever they want*

[Falonn]

1 minute ago, videofx said:

I want to connect it VGA to my OSSC  then HDMI out

You may have better luck with the 8-pin mini-DIN to SCART (and then to HDMI) option for output then.  That's how I've been testing it with the OSSC and it works well.

 

VGA requires separate H-sync and V-sync signals (vs. C-sync which combines both and is used in this circuit), which I haven't done any testing against.

[MrPix]

I do have a library logic for separating CSYNCH into HSYNCH and VSYNCH. If there is a lot of demand for this, I can incorporate it. It's a 50c part.

[ApolloBoy]

40 minutes ago, MrPix said:

Ok, a big question now.

Since this is an RGB output, what RGB socket to people most want to use? Do you want a 9-pin D-SUB, or a DIN socket, or a small PS/2 type socket, or what? Is there a particular type of monitor more of you use, where providing that socket will simplify things and allow cable re-use for the most people?

What have you got?!

I would prefer an 8-pin mini-DIN or full size 8-pin DIN, though I’d lean more towards the mini-DIN since it’s compact and doesn’t need as big of a hole to drill.

Edited May 21, 2020 by ApolloBoy

[+videofx]

31 minutes ago, Falonn said:

You may have better luck with the 8-pin mini-DIN to SCART (and then to HDMI) option for output then.  That's how I've been testing it with the OSSC and it works well.

 

VGA requires separate H-sync and V-sync signals (vs. C-sync which combines both and is used in this circuit), which I haven't done any testing against.

 

No problem. Just let me know what 8pin din to scart cable I need and that will work Thanks!

[+H454]

Just now, ApolloBoy said:

I would prefer an 8-pin mini-DIN or full size 8-pin DIN, though I’d lean more towards the mini-DIN since it’s compact and doesn’t need as big of a hole to drill.

 

35 minutes ago, KylJoy said:

I like using 8-pin mini-DINs wired like the xRGB-mini.

+ 1 to 8 pin mini din.

Tim worhtington's 2600rgb, nesrgb come with it and he has a cable kit for it too (8pin to scart).

https://www.retrogamingcables.co.uk/index.php?route=product/search&search=8 pin

Pre-made scart cable are available as well. wired to the frameister spec.

 

The 8 pin mini probably has the most options when it comes to case mounts and pcb mounts.

Vga is bulky

The sega gensis /megadrive 9b pin whatever is hard to get good case/ panel mount options.

 

A mini din 10 pin ( like the Saturn) would be good if wanted to have chrome/luma on the same connector and use pre made cables.

[+videofx]

I have a SEGA to SCART, BBC Micro to SCART, Sinclair QL to SCART,  Amstrad to SCART, so if any of those cables will work that would be great!

[+KylJoy]

21 minutes ago, H454 said:

... A mini din 10 pin ( like the Saturn) would be good if wanted to have chrome/luma on the same connector and use pre made cables.

I could go with that, too.

[Falonn]

25 minutes ago, MrPix said:

I do have a library logic for separating CSYNCH into HSYNCH and VSYNCH. If there is a lot of demand for this, I can incorporate it. It's a 50c part.

In theory, the LMH1251 provides H- and V-sync out of the box... but when I checked the V-sync line once a couple of weeks ago (out of curiosity when I first got it up and running), I saw nothing at all.  The chip is spec'd for 480p minimum, so I wonder if we're technically using it out of spec as far as the sync lines are concerned.  I vaguely recall the H-sync line was fine though.  Combined with the LM1881's usable V-sync signal and we might have something that could work as-is.  There'll probably be some slight timing differences between the two, but I can't imagine it would break anything.  (I haven't tested it though.)

 

2 minutes ago, videofx said:

No problem. Just let me know what 8pin din to scart cable I need and that will work Thanks!

It's usually this one or the Retro Gaming Cables cable that H454 just mentioned.

 

This circuit also trivially works with "Genesis 2" 9-pin mini-DIN just by replacing the three 75-ohm output resistors with 0-ohm jumpers and using the TTL C-sync output pad instead of the 75-ohm C-sync output pad.  I was just able to finally test this yesterday.

[hpc]

mini-8pin to Euro-SCART as described in 'Falonn's post - I use the same cable he describes.

WARNING: I am known as Mr. Cold Solder Joint - meaning, I have NO such skills - plug-n-play I can do.

 

[+videofx]

Once the design is finalized it would be great to see how to install instructions. Then I can see if I can do a youtube install video

[MrPix]

PM me about it and I’ll see you get one the first day. 

[+videofx]

17 minutes ago, MrPix said:

PM me about it and I’ll see you get one the first day. 

 

PM Sent

 

THanks!

[mattyv316]

My preferred install would be:

8 pin mini-din - MD-80SV

Matching citrus3000psi "helper" board

8 pin mini-din SCART cable

I would run that to OSSC or RetroTink 2x SCART. Then HDMI out.

 

Backup choice for install would be 9 pin mini-din Genesis 2 style port and use a Genesis 2 style SCART cable with components in SCART cable removed. This is how I have my Intellivision RGB modded and works great (HDMI through 2x SCART because the RGB mod won't work with OSSC).

Edited May 22, 2020 by mattyv316
added info

[emmanuelf]

XRGB 8 pin mini-din is the de-facto standard for RGB modded retro hardware.

Starting to put more video standards on it is I think a bad idea. There is already well established standards for that with on the shelf cables : RCA and 4pin mini din.

The only exception I would made it to put mono audio signal on the 8 pin mini din as the scart has audio input too on the same cable.

[MrPix]

3 hours ago, emmanuelf said:

Starting to put more video standards on it is I think a bad idea.

This isn't about adding video standards. It's about this board fitting in many different systems and each community has their own ideas about what a 'standard' connector is
It'll be available without a connector, or with two or three of the top choices requested pre-wired. I just want a handle on what connectors are being requested so I can have the right parts in hand at the best prices.

[+videofx]

1 hour ago, MrPix said:

This isn't about adding video standards. It's about this board fitting in many different systems and each community has their own ideas about what a 'standard' connector is
It'll be available without a connector, or with two or three of the top choices requested pre-wired. I just want a handle on what connectors are being requested so I can have the right parts in hand at the best prices.

Great Idea! It will be easy then to build or buy a cable

[pumpy_heart]

Great work, loving the results! My citruspi install failed, happy to join on to this project. I would like 1 NTSC and plan to attach to a 8-pin DIN. Already have the hole.

[Falonn]

PAL compatibility confirmed!  Notice it's squashed vertically a little through the Framemeister because of PAL's extra hundred or so lines.

 

 

Same breadboard, same connections, same everything.  TMS-RGB works across NTSC and PAL with zero changes!

 

It took some work getting the PAL CV back up and running.  There was a mostly-installed-but-incorrectly-working composite mod that I had to strip back out and restore to original condition.  Then, it just took tapping the five pins right off the VDP and the picture you see above worked immediately.  I fear there are more things wrong with this PAL unit---the controller was completely unresponsive and it seems like the '2' button is being held constantly---but that's not what we're here to test! ?

 

I'll take a closer look with the scope when I get a chance to make sure that things like the color burst lasts as long as the LM1881 is set to expect, etc.

 

But this was too exciting of a result not to share immediately!

[Ikrananka]

35 minutes ago, Falonn said:

PAL compatibility confirmed!  Notice it's squashed vertically a little through the Framemeister because of PAL's extra hundred or so lines.

Well that is exciting news ?

 

It's funny, I grew up in the UK and so my ColecoVision from that time is a PAL unit.  One of the few carts I could afford to buy at the time was Carnival and just assumed that the way it displayed games was normal and by design.  It wasn't until later years when I moved to Canada and started playing an NTSC ColecoVision that I realised that the wheel turning the pipes at the top of the screen was actually supposed to be a circle and not the ellipse I had seen on my UK ColecoVision all those years ago.

[MrPix]

Another Brit reporting for duty! Expat in Austin, TX!

That was my experience too. In the 80s I was busy designing expansions for the Sinclair QL, and the Sam Coupe was designed by some bloke called Bruce on my electronics workbench - which I was evicted from and had to do my work on the packing bench.

Great times.

[MrPix]

I suspected PAL would work outright due to the suppression of the color burst, which causes severe color shifts. The real variance comes in the conversion to UHF, and the different frequency offset in UHF for the color carrier - later stages in signal processing.

That said, there may be small differences between the B-Y and R-Y signals on the 9928 and 9929, as the 9929 might be tuned to the wider PAL color gamut. If observable, they could be corrected by recalculating the resistor dividers after U3. On which note, have you measured the current being sunk by those resistor dividers? You could multiply those resistances up to reduce current to ground, as 150 ohms is quite low and it will cause a little additional heating in U3. Every little bit helps.

[Falonn]

12 hours ago, Ikrananka said:

... the wheel turning the pipes at the top of the screen was actually supposed to be a circle and not the ellipse I had seen on my UK ColecoVision all those years ago.

Oh, wow, I had always assumed PAL TVs knew how to deal with the extra lines to maintain the aspect ratio.  Thinking about it again, I suppose it would have taken effort on the Carnival game developer's part to check the region flag and draw things differently.  Hmm.  I know about the other lack-of-developer-effort differences (usually stemming from 50Hz vs. 60Hz) like different gameplay or music speed.  While trying to reverse this composite mod install, I saw this Tarzan gameplay on a PAL system and the music sounded like the game was running in slow motion to me!

 

9 hours ago, MrPix said:

I suspected PAL would work outright due to the suppression of the color burst...

I did too, but there's nothing like seeing it with your own eyes!   That was easily worth buying, shipping, and repairing the system.

 

9 hours ago, MrPix said:

The real variance comes in the conversion to UHF...

This caught me by surprise.  I've got a little TV tuner box that is supposed to be able to do NTSC and PAL.  I was hoping to use it to confirm the system was back to a working state before moving forward with my own experiments.  I was disappointed at first because the channel auto-scan didn't seem to find anything in the 50 to 70MHz range where I was expecting PAL channels 3 or 4.  (Even though the "Ch. 3/4" trace on the RF box had obviously never had solder in the through-hole and the channel switch at the back of the case wasn't populated.)

 

I gave up with the tuner remote and turned back to the bench to start double-checking all my connections.  A few minutes later, the static snow sound stopped on its own.  I looked over and saw (horribly disfigured) color bars from my test cart!  It had searched all the way up to 510'ish MHz but eventually found it.  I didn't realize the PAL version of the CV used UHF.

 

9 hours ago, MrPix said:

That said, there may be small differences between the B-Y and R-Y signals on the 9928 and 9929...

The datasheet says there are.  Try the top-left drop-down box in my TMS992xA color simulator.

 

Copy this and then click "Load from Clipboard" first to get reasonable colors:

Transform:1.695 2.03 1.14 1 -0.1864 -0.5085 1
Output:Framemeister

It seems like a really big difference on the "Color Bars" test image.  But when going back and forth while comparing the others, it's not so jarring.  Everything is definitely more pink than red in PAL though.

 

In all my digging, I didn't see any PAL-specific YPbPr conversion matrices, so was this just a conscious choice TI made to handle the gamma difference (that I think I've read about?) in PAL TVs?  In the datasheet it's a non-linear transformation between the two.  Only some of the colors have been modified, so the best we could do with resistor changes is approximate things while making the unchanged colors "incorrect".

 

9 hours ago, MrPix said:

... have you measured the current being sunk by those resistor dividers?

Nope, but the Y line is the lowest resistance of the bunch and the math says that a solid white screen would draw 4.6mA in the worst case (minus the lower draw during blanking)... if the circuit were DC-restored at that point, but it's not anymore like it was in ELM. ?  Hmm.  With the 2'ish volt DC bias, that's less great.

 

9 hours ago, MrPix said:

You could multiply those resistances up to reduce current to ground, as 150 ohms is quite low and it will cause a little additional heating in U3. Every little bit helps.

Every little bit of picture quality helps! hehe.  I had tried the resistors in the 15k range but was already seeing some pretty bad color smearing.  So two orders of magnitude bigger is too much.  2x would probably be safe.  Realizing those lines aren't 1V just now, I might try that.  Although, the thermal image of the amp doesn't have me very worried.  We're still way inside the device ratings... but ~25mA total across all three channels average feels more wasteful than the ~4mA I had initially estimated.  That's explains the difference in overall current measurement a little better in the thermal image post.  The amp would consume about 15% of the circuit's overall power instead of the 2% I thought it was.  Hmm.