Backporch: a Swiss tool for classic consoles connectivity

[u1su3su2]

Hey folks,

I wanted to introduce my open-source project, Backporch: https://github.com/semi-simple/backporch

I created this project to address one of my pet peeves: cables can be difficult to source and expensive. Depending on one's need, it's can be typical to have 2 or 3 cables per console.
(Also many of them are not designed as proper transmissions lines with adequate impedance matching (i.e. it's common to have input resistors near the output, in the SCART connector)).

I wanted to create a board where all components can live that can then be connected with cables with no components inside to consoles and to displays.
The hope is that it would allow us to use high-quality but cheap, easily sourced cables. The components on the board itself can be very high quality.

As the project stands today, with no cost optimization and by using Oshpark and Digikey, the cost is about ~20$ per board.

My approach is as follow:
1. Standardize inputs as mini-din 9 and mini-din 8

- mini-din 9 follows the Mega-Drive/Genesis "standard" (i.e. impedance matching resistors and coupling caps are needed), TTL SYNC
- mini-din 8 follows the XRGB Mini / NES RGB "standard" (no impedance matching resistors nor coupling caps are needed), "75 Ohm" (~0.7V PtP) sync

2. Standardize outputs as mini DIN 8 (for SCART) and DE-15 ("VGA")

- Component-free Mini-DIN 8 to SCART cable are easily available. A simple Mini-DIN 8 cable can be used to connect to a Framemeister.
- DE-15 can be used to connect directly to the OSSC. High-quality and cheap DE-15 to BNC cables are widely available to connect to a PVM.

The board includes a sync stripper, so it's easy to use Luma, Green, or even composite as a sync source if needed.

Here are some passive cables that can be used with this board:

- Short, schielded mini DIN 9 to mini DIN 9.
- Short, schielded mini DIN 8 to mini DIN 8
- SCART (input) to mini DIN 8 (output)
- Mini DIN 8 (input) to SCART (output)
- DE-15 ("VGA") to BNC
- DE-15 ("VGA") to DE-15 ("VGA").

Many consoles can be connected by simply cutting a cheap cable and soldering a plug that will fit into that particular console. No components needed. (Refer to https://github.com/semi-simple/backporch for some examples, but a lot more can be done).
Mega-drive/Genesis, NES RGB and a few SuperGuns don't even require doing anything, grab the right cable and connect!

I hope you find this helpful. Please don't hesitate to ask questions, make comments or even request features / changes!

[SCARTicus]

The whole video cabling problem is a real problem, and it needs addressing, and I am glad that you are putting effort into solving it. SCART is worthless, and no professional equipment will directly interface with it. Other solutions for interfacing with good, readily available equipment are still quite expensive.

This is an interesting project, but you really have not solved the problem. I still need an exotic cable to connect most consoles, only now its even more obscure than before. Where am I supposed to buy a Playstation multi-out to mini Din 9 cable? If I have to make a cable, any sort of cable at all to use this product, then it is moot. I would just build a Playstation multi to DE-15 cable, wouldn't I? Big enough DE-15 hoods to house an lm1881 can be found easily and cheaply and a have a few spare already. And at this point I would also have to build your board myself, which is more effort than just one cable.

Now, what would be supremely useful, which you have with this project proven yourself capable of accomplishing, is a device that has a male end that goes directly into the console's AV port with a female DE15 and 3.5mm that I could buy online for $50 or less. Make sure it has an enclosure. You would need a different one for each console, but it would be worth it. Look at how CARBY is built. You do not need to use an input cable with CARBY. It plugs right in. I would buy one for each of my many consoles.

https://insurrectionindustries.com/product/carby-v2/

Please take this as constructive criticism. I am supportive of and grateful for your efforts.

[u1su3su2]

Thanks for the feedback. Your are right, this is far from a full solution to the problem.

It is "turnkey ready" in the following situations:
- Your console uses mini din 9 (Mega-Drive / PC-Engine with SSDS3) or mini DIN 8 (NES RGB / Minigun Supergun)
- You already have SCART cables, are happy with them, but need a sync stripper/booster to go to a PVM / Extron.

To approach a full solution to the problem, we would need one of the cable vendors to offer passive cables that go from other consoles to either mini DIN 9 or mini DIN 8, as appropriate. (i.e., what you suggest, except we would keep the cable that goes into the console and the board as separate things)

Then one advantage is that one doesn't need completely different cables for SCART and DE-15/BNC outputs. Cables would presumably be easier to make and cheaper. Those simple cables would also be future proof: if we get a better sync stripper circuit in the future, we don't have to change all cables. In general I like the idea of buying separate elements that do one thing well.

In the meantime, for some people, soldering quickly a mini-DIN 8 cable to a fitting plug may be less daunting that something with electronics components, especially if they need sync stripping. And again, that component-free cable is pretty future proof.

For others, it may also prove useful to quickly hack something together while waiting for those awesome Retro Access cables to show up!

But I don't know that for a fact, let's see how/if people use this.

[strayan]

Now, what would be supremely useful, which you have with this project proven yourself capable of accomplishing, is a device that has a male end that goes directly into the console's AV port with a female DE15 and 3.5mm that I could buy online for $50 or less. Make sure it has an enclosure. You would need a different one for each console, but it would be worth it. Look at how CARBY is built. You do not need to use an input cable with CARBY. It plugs right in. I would buy one for each of my many consoles.

This is what you mean right? https://www.tindie.com/products/chipnet ... o-adapter/

[BazookaBen]

This would actually work well with HD Retrovision's saturn/playstion/tg16>9 pin din adapters. You'd just need a short male-male cable in between.

[u1su3su2]

This would actually work well with HD Retrovision's saturn/playstion/tg16>9 pin din adapters. You'd just need a short male-male cable in between.

Thanks for that suggestion. Sadly it wouldn't work perfectly for Saturn and Playstation as their signal already go through 75 Ohm resistors internally inside the console (which frankly is the right way to do it). It would work, but produce a dimmer image (2/3rd or the normal brightness range). One way around it would be to short R3, R4 and R5 on backporch.

(The reason it works on the HD Retrovision cables is that presumably they offer a very high input impedance)

Currently on Backporch, these consoles should go with a passive cable to the Mini DIN 8 port instead.

Your suggestion is interesting though and it would be yet another reason to add a switch to bypass the input resistors on the mini DIN 9 connector (or even a potentiometer for fine tuning).

[SCARTicus]

This is what you mean right? https://www.tindie.com/products/chipnet ... o-adapter/

Yes, exactly like that but with a plastic enlcosure, and maybe feet on the bottom of the enclosure to take the weight of the attached DE15 cable off of the console multi port. And for more than just Nintendo. SyncBaby does seem sweet, and it costs about as much as a decent Retro-Access cable.

[u1su3su2]

This would actually work well with HD Retrovision's saturn/playstion/tg16>9 pin din adapters. You'd just need a short male-male cable in between.

Your suggestion is interesting though and it would be yet another reason to add a switch to bypass the input resistors on the mini DIN 9 connector (or even a potentiometer for fine tuning).

Another possibility would be to just add a buffer on the RGB lines (which would also allow removing the large coupling caps) and basically be agnostic on whether or not the console end already has 75 Ohm resitors. It might make sense. Working around existing, cheap and widely available cables is the goal of this project after all.

Keep the suggestions coming, it'll help me build the right thing!

[nmalinoski]

Now, what would be supremely useful, which you have with this project proven yourself capable of accomplishing, is a device that has a male end that goes directly into the console's AV port with a female DE15 and 3.5mm that I could buy online for $50 or less. Make sure it has an enclosure. You would need a different one for each console, but it would be worth it. Look at how CARBY is built. You do not need to use an input cable with CARBY. It plugs right in. I would buy one for each of my many consoles.

This is what you mean right? https://www.tindie.com/products/chipnet ... o-adapter/

Like SCARTicus said, having the device use the type of mini DIN-8 and mini DIN-9 cables used by the Framemeister and Genesis 2/3/CDX respectively means an additional cost and yet another uncommon type of cable (SCART is at least relatively common in Europe, but the DIN-8 stuff seems to be uncommon everywhere); and I agree that the SyncBaby model is the best, most-useful approach, because you don't need anything additional--you plug it in, and it lets you use standard, very common DE-15 and 3.5mm TRS cables.

The SyncBaby idea can also be taken further, like integrating an RGB interface, so one could, with a switch, select between composite, luma, clean composite sync for RGBS, or RGsB, or RGBHV, as desired/available. It should also be possible to add a colorspace converter so typically RGB-only consoles could output YPbPr without needing a SCART cable and an RGB2COMP.

[u1su3su2]

Now, what would be supremely useful, which you have with this project proven yourself capable of accomplishing, is a device that has a male end that goes directly into the console's AV port with a female DE15 and 3.5mm that I could buy online for $50 or less. Make sure it has an enclosure. You would need a different one for each console, but it would be worth it. Look at how CARBY is built. You do not need to use an input cable with CARBY. It plugs right in. I would buy one for each of my many consoles.

This is what you mean right? https://www.tindie.com/products/chipnet ... o-adapter/

Like SCARTicus said, having the device use the type of mini DIN-8 and mini DIN-9 cables used by the Framemeister and Genesis 2/3/CDX respectively means an additional cost and yet another uncommon type of cable (SCART is at least relatively common in Europe, but the DIN-8 stuff seems to be uncommon everywhere); and I agree that the SyncBaby model is the best, most-useful approach, because you don't need anything additional--you plug it in, and it lets you use standard, very common DE-15 and 3.5mm TRS cables.

The SyncBaby idea can also be taken further, like integrating an RGB interface, so one could, with a switch, select between composite, luma, clean composite sync for RGBS, or RGsB, or RGBHV, as desired/available. It should also be possible to add a colorspace converter so typically RGB-only consoles could output YPbPr without needing a SCART cable and an RGB2COMP.

One possible downside of the SyncBaby approach pointed by RetroRGB is the strain on the console's port. A short cable between the console and the device would alleviate that (as would stands, as SCARTicus suggested). Another issue is to have to engineer N devices for N consoles. I do feel like there is room for a one-device-with-electronics + cheap adapter cables approach. But I hear loud and clear that those cables would need to be available and that having to make them is a pain.

If the cables were easily available and cheap, would the Backporch approach work for you, or is it fundamentally more desirable for you to have just one cable or just one device?

[nmalinoski]

One possible downside of the SyncBaby approach pointed by RetroRGB is the strain on the console's port. A short cable between the console and the device would alleviate that (as would stands, as SCARTicus suggested). Another issue is to have to engineer N devices for N consoles. I do feel like there is room for a one-device-with-electronics + cheap adapter cables approach. But I hear loud and clear that those cables would need to be available and that having to make them is a pain.

If the cables were easily available and cheap, would the Backporch approach work for you, or is it fundamentally more desirable for you to have just one cable or just one device?

I agree that port stress is a concern, but I'm not entirely sold on the idea that the dongle approach is the best solution.

A number of years ago, prior to fitting my Dreamcast with a DC Digital, I purchased a Behar Bros. Toro, and, while it does what it advertises, and could ostensibly do the same for any other RGB console that I could make a dongle for, one of its major drawbacks is that it significantly increases the depth of the console's footprint. My Dreamcast would fit just fine on the shelf I had it on, but connecting the Toro meant hanging the Toro off the rear edge of the shelf. I imagine the interchangeable dongle idea would have a similar issue.

The interchangeable dongle idea has another drawback in that, because it would be a single device, adding features catering to a specific console would increase complexity, and thus price, for everyone (See TerraOnion's MODE); whereas catering different devices for specific consoles means more focus on addressing those consoles' quirks.

I think the standoff/leg supports are a good idea for a device that would be swapped out on a regular basis; otherwise, at least for some consoles (PS1, SNES, N64 come to mind), it should be possible to 3D-print a replacement AV shroud that could extend out the rear of the console and serve as a mount for the device while still allowing it to be disconnected and swapped for a different AV cable.

[kitty666cats]

IMHO, what we really need is something like this:

https://www.tindie.com/products/chipnet ... o-adapter/

Only for all retro consoles... I know we’ve got a user here working on something just like that! And, I’m pretty sure, a few others also working on a device like this: now we’ve just gotta wait and see who can drop a whole product line of these first!

[SCARTicus]

IMHO, what we really need is something like this:

https://www.tindie.com/products/chipnet ... o-adapter/

Only for all retro consoles... I know we’ve got a user here working on something just like that! And, I’m pretty sure, a few others also working on a device like this: now we’ve just gotta wait and see who can drop a whole product line of these first!

I agree. We have been discussing this in the five or so posts above your own. Read nmalinoski's comments. A SyncBaby for every console, and with plastic enclosures that extend to the surface that the console rests on (to prevent sagging and wear).

[u1su3su2]

IMHO, what we really need is something like this:

https://www.tindie.com/products/chipnet ... o-adapter/

Only for all retro consoles... I know we’ve got a user here working on something just like that! And, I’m pretty sure, a few others also working on a device like this: now we’ve just gotta wait and see who can drop a whole product line of these first!

This is the device that SCARTicus was mentioning above, and that we were discussing. What you want is roughly what Backporch aims to be, except the cheap passive cables needed are not easily available (unless your source console is already mini DIN 9 or mini DIN 8, or unless you're willing to use SCART as an intermediary) and need to be made by hand at this time.

[u1su3su2]

I added some links for places to source cables (or connectors) for Backporch here: https://github.com/semi-simple/backporch/issues/1

Please don't hesitate to contribute your own links!

[kitty666cats]

Derp, read things in too much of a rush! But yeah, I think that it’s about time to close the book on Framemeister 8-pin miniDIN heh. NESRGB modded consoles are gonna keep said cables alive for quite some time, but with the advent of more and more devices making FM obsolete it’ll be exciting to see a shift in popular connector choices