How to get RGB and Stereo sound of your A8...with just a tiny mod....

[Level42]

Just a pretty long descpritiom about how I set up my A/V outputs.

 

My requirements:

 

- RGB out (from Sophia)

- Stereo Audio out (from Stereo POKEY board)

- as little modding to the case as possible

- NO connectors in the case

 

First I had the stereo POKEY so I thought about using the hole formerly used for the RF output (removing the RF unit is one of those internal mods that are totally OK in my book ...LOL) to put a 3.5mm jack there. Actually, I had already mounted one with a support glued to the PCB.

 

However then came SOPHIA and I need to get the RGB signal out...

 

FJC (Jon) gave me the idea of using a 13 pin DIN socket, like used on 1088XEL. However, drilling 13 tiny holes, scraping away the copper...lot of hacking to do....(check Jon's youtube videos to see how he installs these 13 pin Sockets). I also figured this was nice as there are ready made cables available and I really don't like hacking cables myself.......especially....if it's like a SCART cable that require shielding of each individual wire (if you want to do it according to proper standards).

 

Then Fred_M suggested looking into using a mini-DIN socket instead as he thought there was some kind mini-DIN to SCART standard for (old) satellite receivers. Turns out these were not really that standard at all, but I really liked the idea of mini-DIN as I hoped it would be small enough that I would not have to mod the RF hole.

 

Next I googled around and found that Sega used mini-DIN connectors for their old consoles and the Genesis/Megadrive 2 actually carried all the signals I needed, R,G,B, csync, +5V for the RGB selection and of course stereo audio.

 

The schematic I found was this:

 

 

Next I ordered a ready made high quality cable: https://www.retrogamingcables.co.uk/sega-mega-drive-2-sega-genesis-2-rgb-av-scart-cable-tv-lead

 

Yes it's not cheap, but the main thing is that it has individual shielding for each signal and the rest of the materials is high quality too. Plus there was a possibility to add two RCA jacks to output sound to another device like a serious audio system which I like to have as an option.

 

I also bought the 9 pin mini DIN sockets, https://nl.aliexpress.com/item/5-stks-MD-Metallic-Behuizing-Vrouwelijke-DIN-9-Mini-Pin-Rechthoek-S-video-Adapter-Sockets-Mini/32858526623.html?spm=a2g0z.10010108.1000016.1.72151b72Or15VU&isOrigTitle=true

 

True...not cheap either....but they are hard to find elsewhere...

 

Regretfully, the height of the RF hole on the XL casing is a bit too high to match the socket so I had to raise it. I take an old piece of unused prototype PCB, cut two small parts out, the side of the top of the socket. I glued those two pieces of PCB together with superglue. Next I glued the socket on top of those two piece of PCB (socket "upside down") and then glued the whole set-up to the 600XL PCB using superglue again.

 

This rose the socket enough to be centered with the RF hole. However, when I inserted the plug of the cable, I couldn't fully insert it as the protective rubber around the connector was a bit too thick. Following this I enlarged the hole a lit bit using a drill. (I'm not great a doing mechanical work...the hole is not perfect, the socket is not perfectly straight angled on the motherboard, but that's superglue for you....no time to adjust....)

 

So, now I had all the pins facing up. I soldered on two wires running for left and right audio (GNDs not needed, the socket gets GND from Sophia). I used those breadboard wires with female dupont connectors which fit nicely on the pins of the STEREO POKEY PCB. (I love being able to remove wires for work).

 

Next I had bought a new ready made ribbon cable with the 8 pin micomatch connector for Sophia. I figured out all the signals and soldered them all to the socket pins. I used a bit of hotglue to keep the ribbon to the PCB so everything stays nicely in place.

 

Now.....I already knew that the Megadrive 2 cable had caps and resistors in the color lines which were probably not needed. I tried it with them still installed anyway, and the result was a too dark picture. Following this I opened the SCART connector which has a nice PCB with SMD components inside. I desoldered the caps and resistors and made three wire bridges to by-pass the spots.

Now, the schematic for the Megadrive 2 cable als includes a 180 Ohms resistor in series with the +5V output. I figured this would be good to use because SCART specs say +1V to +3V is the voltage to select the RGB input. Since Sophia also provides +5V (like the Megadrive) I figured it was smart to keep it there.... However....when I tested everything the TV spontaneously switched from AV input to TV (RF) display very often. It puzzled me, but then figured the only difference was that 180Ohms resistor. So I removed and bypassed that too on the SCART PCB and bingo....no more weird TV behavior !

 

The results can be seen in the pictures. I also started a mission to find the best CRT TV for displaying classic consoles and computers at the same time...I already had a B&O MX4000 which was nice, but I recently picked up a MX8000 which is much more modern and made a MUCH MUCH better picture.

It's hard to make good pictures of a CRT display, but this was the best I could do with my iPad camera.....not the best either of course.

 

All in all this took a long time, I went through several stages of "I'll do it that way.....no I'll do it that way".....but in the end I think it was really worth it.

 

I have the best possible analogue picture and sound output now, and minimal modding to the case. I'm happy

Edited July 20, 2018 by Level42

[+mytek]

Be nice to make a little PCB for that with a Micro-MaTch header. Or better yet one with a DIN-13 and the header, so that you could use a ready made cable. But I'll shut up before I get myself in trouble .

 

BTW, great job at modding everything.

[Level42]

I actually thought about doing a tiny PCB for it....and make three types of connectors possible: Sophia Rev,A, Sophia Rev.B and VBXE.

 

But I figured I'd probably be the only one doing so much and investing so much in connector and cable.....

[Level42]

This helped me to figure out the signals ....of course I didn't use pin 4 and 6 as they are useless.

 

https://gamesx.com/avpinouts/genesisav.htm

[Level42]

And this is my professional drawing of the pinside of the mini DIN 9 pins connector...

 

 

Make sure you solder all GND wires to (one of the) metal shield tabs of the mini DIn socket.

Edited July 20, 2018 by Level42

[80s_Atari_Guy]

Nice, really nice picture.

 

Where did you get Sophia RGB ? All I see in this forum is Sophia HDMI (rev c ?)

[Level42]

...and this is what I puzzled out which are the connections of the MiniMatch connector for REVISION A of Sophia.

[Level42]

Nice, really nice picture.

 

Where did you get Sophia RGB ? All I see in this forum is Sophia HDMI (rev c ?)

Geez....this says so much.

 

Even I get frustrated having to find info about the brilliant Sophia's through lots of posts in two threads here...)

 

Sadly, Sophia is a bit of a hidden treasure... the thread in which it was announced doesn't even mention its name....nor really clearly (for "laymen") says what it is....(How many Atari users know what CPLD is ?)

 

I think this was also caused by the fact that Sophia wasn't fully ready when the thread was started by a simius....nor didn't he think there would be (so much) interest in ready made Sophia's....

 

Further, Sophia is often misspelled as SoFia (some youtube videos even mention it like that.......NIR !!!) which makes a google search often fail....

 

Sadly, there is also not a single website which contains all information about Sophia....

(F.I.. right now I'm looking for the info how to install the micromatch connector on my USB blaster... LOL)

 

Anyway...here is the thread about RGB/component (yes, besides RGB it can also put out Component Video which should be of interest for US A8 users) Sophia:

 

http://atariage.com/forums/topic/258702-new-development-gtia-in-cpld/

 

I am sure a thread title somewhat like " New: RGB/Component output for A8/5200 now available" would have rendered a lot more traffic

 

Oh and the picture on the Bang & Olufsen MX8000 TV is the best CRT picture I have ever seen.

Edited July 20, 2018 by Level42

[80s_Atari_Guy]

Thanks for the link.

I agree about Bang & Olufsen. I knew someone, a few years ago, had a MX4002 -- the 21" version. Very nice picture, and stylish TV.

[Level42]

I started with a MX4000. The 4002 is better from what I've read but I don't know the exact differences.

 

The MX7000 has the same chassis as the 4000....

 

The follow-ups were the MX4200 and MX8000. These were the last generation of 4:3 TVs from B&O and IMHO the best by far. They are also relatively new as production was between 2002 and 2005. Mine has only little over 8000 running hours (nice you can check that ) and it looks like new.

Interestingly the MX4200 uses a real flat Panasonic tube where the MX8000 still uses a not completely flat Philips CRat. My guess is that Philips already ad stopped production of the smaller CRT.

 

At the moment I have a 4000, a 7000 and an 8000. The newer ones have LOTs of advantages so if you're looking into them go for 4200 or 8000.

 

I'm looking at also getting a MX4200 soon.

 

I'll be comparing them all PLUS a Sony Trimtron TV to keep things honest :)