PC Engine EXT RGB cable

[kamiboy]

Spoiler

I would love to build one of these things myself. Anyone privy to the construction of the plug that attaches to the back of a PC Engine, or where such parts might be sourced?

[mvsfan]

Digikey probably has those connectors in stock but you really have to measure it to be absolutely sure - they have SO many connectors.

[Shoryukev]

When I finally get a Turbografx or PC Engine, I plan on just using a handful of individual crimp connectors on each pin, seems like a really easy way to do it. Either that or just solder directly to the pins and use the big cover on the american turbografx to cover my electric spaghetti

[Guspaz]

The dbGrafx Booster seems much easier than all that... Stonage even has it in a case now.

[kamiboy]

That is not what I am looking for. It is too big and bulky.

[kamiboy]

In regards to digikey, they might appear to have lots of things, but if you are looking for something unusual and old chances are the item is listed as obsolete and no longer in stock.

The only connector I find on digikey that comes close is indeed obsolete, and no longer carried.

[viletim]

That's not a matching line connector/shell. That's why you see glue visible in the photo.

The connector on the PC Engine is fairly standard connector (but old fashioned), but an unusual size. Similar situation to the 23 pin D-sub connector.

[kamiboy]

Yeah, I spotted the glue after making the post. It is a shame. I would love to find a matching connector housing combo that takes up very little space and looks sleek.

One could even power the PC Engine from the rear port and contain everything going in and out of the systembto the rear port.

[Fudoh]

I found this approach by bigsanta http://nfggames.com/forum2/index.php?topic=4283.0 much more convenient.

[gojira54]

http://www.samtec.com
SSW-123-02-T-T-RA or
SSQ-123-02-T-T-RA
PCB mount tho

Personally I don't want take up the ext bus, and putting a DIN connector & amp inside the console is much neater/better

Here's my ghetto test amp using one of those connectors;

[kamiboy]

For the record, I have already RGB modded my various PC Engine systems using DIN8 sockets. This project is just for the sake of curiosity. The ultimate goal is for something sleek which matches the minimalist styling of the CoreGrafx console, which in my opinion is the most aesthetically beautiful gaming console ever made.

Having a tumor of wires hanging from its backside is easy, but not desirable.

I've already found the connector in the picture above, and hopefully I can locate the right housing that is both small, sleek and can house Tim's AV driver board plus maybe even a 9V power connector inside it.

[kamiboy]

The connector from Samtec arrived today and it does indeed fit the EXT port of the PC Engine perfectly. The bent pins makes soldering the connector onto a standard prototyping PCB quite easy as the pins adhere to a standard pitch.

Now all that remains is to find a good housing for the connector and the PCB. Anyone have any suggestions? I want something sleek looking that does not take up too much space, but has enough volume on the inside to house an RGB amp, which should not take up much space.

Since the parts are readily available I imagine that if someone wanted to they could make a pretty professional looking PCB that interfaces with the connector, and appropriate housing creates a rather sleek looking RGB cable for all PC Engine models equipped with a EXT port, nullifying the need for any modifications, or having an ugly growth of PCB and cables hanging from the rear end of the ever comely PC Engine.

[kamiboy]

I think I've found the housing that I desire. In the time until I have it in hand I thought about the RGB amp that I want to go with. I originally wanted to go with Tim's AV Driver but after looking up its dimensions it is clear that it will not fit inside the housing.

I then remembered this old amp.



I happen to have all the parts to build it sitting around, and I even have an old ugly circuit I built using the schematics around. I whipped up a test rig hooking it to my CoreGrafx via the EXT port and the results are good looking enough. A bit darker than the THS amp though.

I think I want to build a cable using that circuit, but before I do, I remember some people here shitting on the C1815 amp designs. I believe they were mostly dissing the amps which use just the transistor with no additional components though.

So my question to those who actually know about electronics engineering. Is there anything unsavoury about the above amp for the PC Engine or not?

[ApolloBoy]

I originally wanted to go with Tim's AV Driver but after looking up its dimensions it is clear that it will not fit inside the housing.

You sure? The AV Driver is pretty tiny.

[kamiboy]

According to Tim's site it is about 2cm by 3cm, in which case, yes, I am pretty sure it won't fit. I'll be buying one in the future regardless so I'll only know for sure then. For now I'd like to give the C1815 a try, unless it is not kosher.

[kamiboy]

So, I got all the parts in and thought I'd finally get my version of the PC Engine ext SCART cable built. For the SCART part of the cable I purchased a very high quality SCART cable which once upon a time cost a fortune, but can now be had for cheap. I am going to buy a bunch more of these cables while they are still in stock for future projects as they are simply great.

For the housing I searched ebay for DB37 housings and chose the most stylish looking one I could find. I settled on one with a chrome finish which matches the SCART cable. But I would not recommend it for a number of reasons. Firstly, even though it looks plenty spacious enough on the outside, its insides are actually rather cramped. Secondly, I discovered that width of the housing is just a hair too narrow to fit the left and rightmost row of pins, which is unfortunate because those are the most important, carrying audio on one side, and RGB on the other.

Alas this limitation turned out to be moot since I discovered that for the connector to be insertable into the PC Engine it would have to protrude out of the housing much more than I would like. It has to protrude so much that one can easily see the metal connectors on the back, in addition to any wires one might have hooked to those pins, which makes for an ugly display, to say the least. I put some tape around the connector to hide these and reduce the ugliness, but to little effect I fear. The results did not turn out as sleek as I had hoped.

The connector itself is problematic too. For some reason it ended up being fiddly, and not a tight secure fit as one would desire. Not sure if the connector is at fault, or my manhandling of it during the building process.

As for the amps, I chose to build the one I listed above since I had all the parts for it. This, I once again do not recommend others doing. The four transistors, 24 resistors and 8 capacitor plus all the various power, sync, RGB and GND cables needed to make them work take up considerable amount of space. To make matters worse I only had relatively bulky electrolytic capacitors to work with. Those ended up demanding the lion's share of space on the circuit board. For lack of space I had to skip the two 10uF capacitors that are supposed to connect to the audio output. Not sure what they are needed for, but I imagine some sort of noise filtering.

Frankly I am quite amazed that I managed to get it all to fit in such a cramped compartment. But this of course came with its own share of tribulations. After the arduous task of planning out the layout of the circuit and hooking everything up as efficiently as possible I had to content with several broken traces and snapped cables once I tried to fit the housing on top of the bulky mess.

Diagnosing the problems sure was a barrel of monkeys. But this is par for course whenever I try to build a custom cable, so I am always prepared for the old teeth pulling ride when I start on such endeavours.

Anywaste I finally managed to get everything working with the housing in place, and I then proceeded to drown the insides in a german bukkake of hot glue in hopes that it will help keep things stable. But I do fully expect the cable to fall apart like a Chinese motorcycle the next time I try to use it. That is why I hate making my own cables.

I could not spot any visual faults in the RGB image quality of the amp I chose to go with. Alas I was too exhausted to be arsed with a comparison with the THS amp based cable that I have here somewhere.

In conclusion, building a sleek looking boosted SCART cable that just hooks up to the back of EXT port equipped PC Engines is very much viable. But such endeavours would be better served with a custom amp circuit board designed to work with the EXT connectors available for purchase. Something with mounting holes for the connector, and any parts for the amps, plus the output RGBS,+5&GND to the SCART cable would make for a much neater setup. It would do well to be designed for a specific connector insides so that it can sit flush and stable without the need for hot glue. But I leave that exercise to some other enterprising modder. I venture that there is some money to be made there.

Pictures of the project below:

Spoiler

[Guspaz]

I doubt there's really much of a market for such a thing, because it's essentially going through an enormous amount of effort just to make a smaller version of the dbgrafx booster, a product which already exists.

[kamiboy]

Looking at the many competing hobbyist projects kicking around here I think it is safe to say that there is always a market for a better product. That booster is unnecessarily monstrous, and ugly.

Not that it matters, I got my cable.

[Guspaz]

I'd wager that you've got an opinion there that isn't very widely held: you're not talking about a better product, merely a smaller one. And the dbGrafx Booster, while it's not small, is definitely not "monstrous and ugly". In fact, it's pretty similar to the design of the console itself:



Something coming off the back of a console like that is likely to be hidden away anyhow, and if it isn't, it fits right in.

I don't get where your hatred of the product is coming from.

[Woozle]

The dbgrafx booster is too bulky and kinda ugly. It also has a bunch of stuff that RGB/pvm users don't need or care about.

I might try to make a ths7374 pcb which can fit in the housing kamiboy is using. Kamiboy, would you mind providing dimensions of your homemade pcb?

I think it would be nice to have a small simple board with RGB, audio, and power. Especially something suitable for DIY folk.

[kamiboy]

Yeah, it sure does match the garish redesigned stylings of the Turbografx, alright. The comly PC Engine though, that is another story.

Woozle, I am afraid that I did not measure the PCB dimensions, and the housing is now hot glued into place so I cannot remove and measure it.

But the width of the connector is about 5.8 centimetres, and the board width was about 5 centimetres, I reckon, because I did not include the left or rightmost row of pins. With another enclosure you might be able to have a full length PCB. The depth would be about 2 centimeters at its widest point, but then it had be narrowed down considerably to avoid the screw points, and continued for maybe 0.5-1 centimetres. The narrow width of the PCB would be around or just under 2 centimeters. If you look at the pictures I think you will understand.

If you want to build a PCB I strongly recommend buying a DB37 enclosure first, then fashion a PCB to fit the intricacies of its inside. Each enclosure is different on the inside.

That being said a THS based amp can be built to take a lot less space than the transistor based one I rolled with. That should leave you plenty of space to maneuver.

The best approach is indeed to design a PCB using appropriate software, and then have them manufactured in low quantities by a company that specializes in that. Ready for soldering on the necessary parts onto the various PCB pads or holes. The best PCB design would have two big holes so it can fit around the enclosure screw points, then it would have mechanical stability without the use of hot glue.

But then that would marry it to that particular enclosure design, which might not be the optimal choice.

[Woozle]

How are you handling audio? Should an audio amp or at least pass-through circuit be included?

Is it possible to power the PC engine from the ext port? (Do you know the required amps/volts?)

[kamiboy]

No audio amp is required, I just route the audio out pins from the ext port to the SCART cable. The circuit diagram suggests routing the audio lines through a pair of 10uf capacitors, for unknown reasons, but doing so is unnecessary it seems.

As for powering the PCE, yes, you can via the Vin pins of the ext port. That is how the PCE is powered when inserted into the IFU30. I believe you would need 5 Volts and about 0.5-1 amps. So may be doable from a USB charger adapter, which are 500mA 5V. But do not quote me on that.

But be aware that powering the PCE from the ext port bypasses the on/off switch on the front.