I'm a bit skeptical about a possible board feature pushing a composite signal through pin 7. That would require a special monitor or adapter cable to a non-TTL monitor, when the standard rca connection could have been provided. It is also a bit contradictory for CGA, MDA, or EGA to have that per each standard's pinout:
https://minuszerodegrees.net/mda_cga_ega/mda_cga_ega.htm
(Pin 7 on CGA is listed as reserved, I suspect to prevent clashing with incompatible MDA video signal by accident)

I think you are simply looking for cards that can provide a composite signal. If a card existed that could pinout to pin 7, then it would be simply a matter of tapping into the board somewhere for a connector. But really it would be any board that has a composite internal or external. So any CGA board ?

Here is a kind of similar question, although I think that conversation ended with creating an adapter off the de-9 to create a composite signal off the TTL CGA signals, and not actually there being a pin 7 composite connector being used.
How hard would it be to make a CGA card?

The ATI Graphics Solution REV 3 a.k.a. Commodore PC 10 Advanced Graphics Adapter Card can provide composite both on the header and the DE-9 port. A DE-9-to-RCA adapter was included with a Commodore PC 10 system.

My twin head card has an internal RCA jack. There isn't really room on the slot cover, as it had a de-9 for a monitor and a 25-pin parallel. But I think they had done things like this to support an internal monitor. I think this came from a compaq portable. So as many cards had the full circuitry, tapping in could be easy. Yes some cards had headers too. But making your own adapter doesn't look too bad either. But I wouldn't limit it to the ones that support it on pin 7 of the de-9.

well, I´ve found at least fourfive different ways of convert the signals (some are simillar), including the "original" one, in the IBM Color/Graphics Monitor Adapter tech manual, page 32, there is the schematic of the output circuit. The composite is obtained by mixing the RGB, to which is added the synchrony signal that is obtained by mixing the generated HSYNC and VSYNC , using an XNOR. all through a digital buffer and then an array of resistors, with an output transistor....

or inject the RGB directly to a TV

My question is because I have read in some places about this, that some cards put the composite video signal on that connector pin. Knowing that, what they are, expands for those interested the number of cards that can be used with this signal. Due to the difficulty of obtaining a CGA/EGA monitor I have looked for cards with composite output, but either I have had little luck finding them cheap, or the few times I have done so others have beaten me to buying them (the last time was the most painful, an excellent deal, several card from CGA to VGA some 8bit friendly ones and cheap)... those without visible composite connector trend to be cheaper, but some have internal pins or pin 7 output. maybe sellers ignorance make them put lower prices..

This is something similar to making a list of 16-bit, 8-bit friendly VGA cards (I have found a couple lists of this)

kinetix wrote on 2024-01-20, 02:17:

My question is because I have read in some places about this, that some cards put the composite video signal on that connector pin. Knowing that, what they are, expands for those interested the number of cards that can be used with this signal. Due to the difficulty of obtaining a CGA/EGA monitor I have looked for cards with composite output, but either I have had little luck finding them cheap, or the few times I have done so others have beaten me to buying them (the last time was the most painful, an excellent deal)...

This is something similar to making a list of 16-bit, 8-bit friendly VGA cards (I have found a couple lists of this)

Just keep looking for a deal on an IBM CGA card. For experiencing composite colors, this card is recommend.

I was also looking for an all-in-one type of card for my 5170, got an ATI EGA Wonder (with composite RCA jack) card but unfortunately the composite is in black & white only.

Besides the composite, if I can't find one of these cards, either I will make one or a couple of converters, or one of the mods to a CRT TV to inject the RGB into it.
...
damm, I have so many projects on the pipeline....
Just today I spent a lot of time deep cleaning an IBM PS/2 model 50 that was almost destroyed and I rescued by pure chance from its owner. The amount of dirt was incredible, but now is almost pristine, except by the spots were I had to scrap the rust (will paint it latter). I had to disassemble the keyboard down to the springs and keycaps. And its neophyte owner once decided to take it apart, the screwdriver slipped and destroyed 5 resistors and a line. I have the schematics to see when I can fix it. At least it has the video on the motherboard, otherwise finding a microchannel video card would be almost impossible for me. Anyway, I´ll have to build anew the bottom and the back, both disappeared in the garbage dump right before I rescued the rest, as the computer was almost completely disassembled. He told me the last time it was used was around 1999-2000.