TMS-RGB: An RGB Mod for 2020 and Beyond

[Procrastin8]

On 5/19/2021 at 10:24 PM, Ikrananka said:

@Falonn I hear you about real life keeps getting in the way ?  I still would love to work with you on the component video board.  I really want to be able to take your component video schematic once it's available and design a PCB with the same footprint and mounting design as 5-11under's board.  That way anyone with 5-11under's board can easily upgrade to the new board (me included).

 

 

But then it'd be great to finalise the CV palette project beforehand and so I have made a start on writing this up and will send it to you for review (if that's okay) when I have something worthwhile for you to look at. 

It's been almost a year but I stumbled on this as I am trying to achieve the essentially the same thing: I'm making a TMS9128 video card for my homebrew computer and I want YPbPr output. I am currently using the Tatung Einstein circuit just so I can work on software while I figure out the hardware side (I did try and build the hackaday RGB circuit but tapping into YUV before converting to RGB but I didn't get it to work. I probably messed up wiring somewhere.) Would love to know if there is progress here and to offer breadboarding/prototyping support or even just to look over what you have in an unfinished state. I guess it's probably best to just start with the final v2 board design of the TMS-RGB and tap into the YPbPr lines and leave off the big expensive RGB converter? Also seems like I would want the THS7314 as there is no need for the 4th (sync) signal. 

[Falonn]

10 hours ago, Procrastin8 said:

I guess it's probably best to just start with the final v2 board design of the TMS-RGB and tap into the YPbPr lines and leave off the big expensive RGB converter? Also seems like I would want the THS7314 as there is no need for the 4th (sync) signal.

Without checking my notes, this is close to what I remember.  I think one of the smaller ICs might be able to be left out, too, because it mostly only had to do with giving the sync signal a sharper, stiffer output than the sync stripper was capable of.  I was even wondering if the BOM couldn't be collapsed another line or two by using a THS7314 (or '16) on both the input and output.  But then you'd need to find a separate solution for the sample-and-hold, defeating most of the benefit.

 

I'm still putting myself through a kind of electronics curriculum--reading textbooks in order (E&M, circuits, and now ~60% done with electronics) and doing all the exercises along the way.  (The basics finally don't scare me.  I think the most important thing I learned is that it's Ohm's law all the way down; all of the more advanced analysis techniques seem to boil down to just applying it repeatedly until every problem is solved.) 😂

 

The component version of the board is still on my radar, but my self-learning progress is creeping along a little slower than I'd planned.  After the general books, I have a few others that are more specific to analog video (HF noise, Poynton, etc.) that I'm going to skim explicitly for TMS-Component info.  And then I think I'll finally be ready to do a nice job.

[rwest]

Hi,

 

i have a couple of these boards and want to use a 9 pin din jack. I can’t seem to find a panel mount type in all my searching. My boards came with board mounted jacks and in my searching I came across a small PCB to use those on, but alas can’t find them again! 

 

If anyone has links to either part, I would appreciate it.

 

Thanks,

Rutager

[+-^CrossBow^-]

35 minutes ago, rwest said:

Hi,

 

i have a couple of these boards and want to use a 9 pin din jack. I can’t seem to find a panel mount type in all my searching. My boards came with board mounted jacks and in my searching I came across a small PCB to use those on, but alas can’t find them again! 

 

If anyone has links to either part, I would appreciate it.

 

Thanks,

Rutager

 

Panel mount 9pin is something I've only found references to on AliExpress. I've tried to order twice now and both orders ended up getting cancelled around the time they should have been delivered so I'm not really sure they exist. Then again, they must because SainT looks to be using them on his new 7800GD although he has them soldered to his PCB but they appear to be normal panel mount style.

 

As for the PCB breakouts it depends on which 9-pin mount style you are asking about? I believe the ones I'm using I originally found on OSHpark or PCBWay before designing my own to have made. But those are only for the PCB mount style and not panel mount.

 

[rwest]

So after some more searching I found these and I ordered 5, we’ll see. They are located in Seattle. Ordered some rainbow ribbon cable too.

 

https://vetco.net/products/9-pin-mini-din-female-panel-mount-jack/pan-md-67000-9s

[+-^CrossBow^-]

11 hours ago, rwest said:

So after some more searching I found these and I ordered 5, we’ll see. They are located in Seattle. Ordered some rainbow ribbon cable too.

 

https://vetco.net/products/9-pin-mini-din-female-panel-mount-jack/pan-md-67000-9s

Oh, I did know about those but they are much too large for the installs I do and need them for and I'm not wild about how those style have to be mounted.

 

[Ruggers Customs]

14 minutes ago, -^CrossBow^- said:

Oh, I did know about those but they are much too large for the installs I do and need them for and I'm not wild about how those style have to be mounted.

 

The breakout boards I sent you are actually designed for those type jacks.  I used them briefly in 2016 but found that some Genesis 2 cable plugs from certain manufacturers were too large in diameter and didn't fit.  I needed something that was universal so I switched to the pcb mounted jacks which are more consistent in size.  

Edited April 4 by Ruggers Customs

[+-^CrossBow^-]

47 minutes ago, Ruggers Customs said:

The breakout boards I sent you are actually designed for those type jacks.  I used them briefly in 2016 but found that some Genesis 2 cable plugs from certain manufacturers were too large in diameter and didn't fit.  I needed something that was universal so I switched to the pcb mounted jacks which are more consistent in size.  

Understood, but I was hopeful that the ones I had initially ordered from Ali might still fit the breakouts you sent me as that I think is pretty standard fair. But until I have those in hand I can't answer anything beyond speculation.

 

[ApolloBoy]

I once found some interesting panel/PCB mount hybrid mini-DINs on AliX, haven't used them yet but they might be a nice alternative to those Vetco jacks. They should also fit regular PCB mount breakout PCBs too: https://www.aliexpress.us/item/3256804496663705.html

[+-^CrossBow^-]

2 hours ago, ApolloBoy said:

I once found some interesting panel/PCB mount hybrid mini-DINs on AliX, haven't used them yet but they might be a nice alternative to those Vetco jacks. They should also fit regular PCB mount breakout PCBs too: https://www.aliexpress.us/item/3256804496663705.html

Yes...that is what I've tried to order 2 other times now. And the pins are different between the two types. The pins are in more of a circular arrangement exactly as you see it on the connection end where the cable goes in, while on the PCB mount they are lined up in 2 rows. The PCB mount type I can get without issue and have those on hand with PCB breakouts I have made for them. But the panel or bulkhead mount style I've not had actual luck in getting a hold of... yet.

 

[Gábor Orvos]

Hi everyone!

I bought a TMS-RGB-V2 board recently from VideoGamePerfection.com and built it into my Texas Instruments TI99/4A. It's a PAL version with TMS9929A IC (Attachment#1).
I think the orientation is correct (A#2), and the soldering should be OK as well (A#3).
Previously I owned a Samsung LE40B650 LCD TV with component input, which had an acceptable picture with the TI, blue and violet colors were distinguishable (A#4)
(captured with screencap application: https://wiki.samygo.tv/index.php?title=Content_Library_applications_list#ScreenCap ). Unfortunately the Samy TV "died" last year, and my new 4K LED TV (a 50" TCL) does have only HDMI and composite inputs, so I decided to buy a Medusa retro scandoubler: https://lotharek.pl/productdetail.php?id=135 In theory it should accept component input as well, but in practice it doesn't.
I hoped that I could get a colorful picture with the TMS-RGB-V2 using the SCART input of the Medusa. Unfortunately the picture lacks almos all blue shades (A#5).
Blue and violet colors are undistinguishable, background is gray instead of cyan/light blue. I tried with a noname (Vortex) LCD TV directly via SCART as well, but the same occurs (A#6).
I checked all the solderings with a multimeter, and everything seems to be OK. 
Undusted my cheap chinese RGB/YUV to VGA converter (a Gonbes GBS-8200), which converts component input to VGA. This gives an acceptable result (distinguishable blue and violet), but the picture is washed a bit, and has wrong white balance. (A#7)
Attach the TI to the Gonbes via TMS-RGB-V2's RGB output, the picture is a mess, no matter what output resolution I choose (A#8, A#9 & A#10)
The TI motherboard has a number on the top, near the keyboard connector (ET 03163) (A#11), and an another one on the bottom, near the DB-9 connector (1039026-5J) (A#12).
What should I do? Is it a defective unit, is the TMS-RGB-V2 incompatible with my motherboard, or are there any tricks (like in case of NTSC Colecovision bypassing the L9) to improve color fidelity? Otherwise picture quality (sharpness and stability) is flawless. There's a trimmer next to the TMS9929A, I assume it adjusts the clock frequency. 
Perhaps bypassing the 75Ohm resistor on the blue output line would help, but this would affect the white balance as well.

Thanks your help in advance: Gábor

Edited July 31 by Gábor Orvos