Amstrad GX4000 question

[kingrat101]

I know it's been asked on here before but I have some other specifics that I would like to know for the Amstrad GX4000. First off I live in the U.S. and dont have a TV compatible with SCART. I use an Atlona PAL to NTSC converter that I use to display PAL games on my NTSC AMIGA CD32. I was looking at maybe getting a SCART to S-Video cable like this one https://www.amazon.com/MonsterVideo3-SCART-Stereo-S-Video-Adapter/dp/B0000D8CIC/ref=sr_1_6?ie=UTF8&qid=1481618378&sr=8-6&keywords=scart+to+s-video

and I know I will need a step up converter too. I haven't really looked at one specifically but do you guys think a 300 watt one will work? and If so, will I be all set with this stuff?

Thank you

Edited December 13, 2016 by kingrat101

[phoenixdownita]

The power supply of the GX4000 is a pos, if you plan to use the C4CPC flash cart you'll likely toast the GX4000.

I use a replacement power supply, it's a simple 9V 1A power brick barrel connector (can't remember if center positive or negative right now).

 

The cable you show will not work, the GX4000 does not have SVideo out of the Scart connector (which was non std anyway to begin with), only RGB or composite, and at that you need the right cable (I know I had a composite to Scart but I needed the opposite, so I simply desoldered the composite and soldered it in the right spot as Scart always supported in/out kind of a deal, pin 17 and 18 are involved if memory serves).

 

I used it with a couple of cheap NTSC/PAL to HDMI converters and it worked, only thing there's a couple of games that muck around with the video chip timing and generate non std signals (mid screen sync changes and others) that do NOT work very well in that setup [tearing, rolling etc.....] for which only a direct connection to a PAL TV would do afaik.

[kingrat101]

Ok cool thank you very much for all the information and help, it seems like a lot more work than it's really worth. I could always pick one up to add to the collection and use emulation or something too.

[carlsson]

Over here, we tend to use adapters more than custom made cables. I believe if you plug in something like this one into the GX-4000, and set the switch to output, you will get composite video + stereo sound. Never mind that the auction says RGB, because neither the composite nor the S-Video outputs will handle the RGB signal anyway.

 

https://www.amazon.com/Scart-Composite-S-Video-Audio-Adapter/dp/B006RBMJ46/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=atariage&linkId=c7eedf5eede0ce2a11b41f74d9ec73fe

 

Of course it is still PAL but at least the connector is overcome.

[alex_79]

Just ensure you don't have the French version, because, according to the manual, in that case the scart output is rgb only, no composite. Those SCART to rca/s-video adapters only directly connect the scart pins to the corresponding rca and/or minidin ones. There's not circuitry doing signal conversion inside them, just wires.

If the device outputs composite through scart (it can also output both RGB and composite at the same time), then you will have composite on the yellow rca connector, but you won't have s-video out in the mini-din one (you'll only have composite signal on the luma pin).

If the device outputs s-video through scart (rarely used as it wasn't part of the original standard, and mutually exclusive with both composite and RGB), you'll have s-video on the mini-din but not composite on the yellow rca (just luma).

If (like the French version of the console) the device outputs only RGB, you won't get no composite nor s-video, as the composite pin will only carry the "sync" signal.

 

excerpt from the manual:

 

The full manual is here:

http://www.cpcwiki.eu/imgs/b/be/GX4000_User_Instructions.pdf

[phoenixdownita]

carlsson got it right, now I remember using one of those bidirectional things first and then getting curios and fixing the cable I had been given with the system (obviously untested).

 

Wrt the power supply replacement it is really a std cheap part, so don't let it discourage you.

Mind you that without a C4CPC it's hard to find games for GX4000 and they are .... shall we say .... underwhelming to put it mildly. since the C4CPC came around there's been a couple hundreds CPC games ported to work on the GX4000 (absence of keyboard being the most glaring difference), as I have no attachment to the CPC series I can only say I am not exactly impressed, A8/C64 mop the floor with it and even the MSX (Konami games mostly) is better imho, but that's just me.

[carlsson]

The original GX4000 PSU (the one referenced as a "pos" above) is rated for 11V 500 mA, center positive polarity. Supposedly the machine consumes 450 mA including RF modulator, plus 80 mA for the C4CPC cartridge which thus exceeds the rating. Inside there is a voltage regulator that brings down the voltage to 5V, which is why any PSU rated 9-12V with at least 750 mA (1A is great!), as long as you have the right polarity, will work. Note that most of the systems you may already own may actually have center negative polarity (Genesis, Famicom, Jaguar etc) but an universal PSU with reversable polarity should do the trick.

 

I think the CPC series are known for having theoretically impressive capacities, but that game programmers may never have utilized it, or rather got away with colour improved ports of ZX Spectrum games. In that respect it fared better than the European MSX games, which often were straight Speccy ports, sometimes not even utilizing joystick support. The latter CPC models like the 6128 Plus and GX-4000 have additional graphics hardware in terms of smooth scroll (previously possible through hacking), hardware sprites, larger palette etc that though came much too late (1990) to build a strong library. Of course the size of the customer base also had something to do with it. If the C64 had not sold those 10-17 million units and stayed on the market for 10+ years (at least by European standards), it would never have been pushed to its limits commercially.

[BillLoguidice]

I'm an American with various CPC464, GX4000, and CPC6128/Plus units. I agree 100% about the nonsense original GX4000 power supply. It will blow out at the first whiff of a flash cart. The good thing is that it's quite easy to use a universal power supply with it (basically an old mobile phone style charger), so you don't even need to convert the power. I also agree that even with a flash cart, it's very difficult to find much interest with the system, particularly since a lot was, as carlsson noted, half-hearted ports that didn't necessarily take advantage of any features (and certainly not the features of the GX4000). Even the few GX4000-specific (and Plus) games that did make good use of the system really aren't that inspiring unless you were into the machine back in the day (in my opinion).

 

Much more interesting to me is the CPC6128 Plus. While I have a monitor for it that powers it (yes, it's one of those systems that required either the monochrome or color monitor for power), I use it mostly without that because I have the modern day SCART and power adapter, which again, allows me to forgo having to do the usual power conversions. I then run the SCART cable through my XRGB-mini, which takes care of any issues with the video conversion and makes sure I get full color support, etc. At least with that setup I can do some more of the computing stuff with it, and all games and other software work, unlike with the GX4000 (although a lot of effort has been made in that area). The only downside is that my Plus unit is a French model and that means an AZERTY keyboard layout, but that's easy enough to solve by simply running the UK OS.

[kingrat101]

Oh ok, so I wouldnt even need a step-up/down converter? I've got a ton of genesis psu around here. Sorry guys I've never imported a european system. So it just seems like it may not be the best sort of experience, in terms of games.

Edited December 14, 2016 by kingrat101

[CatPix]

One issue with CPC games as well is that lots of games are "local".

THere are tons of good CPC titles I could tell a Frenchman to try.... But I wouldn't advice non-French speaking people to play, say, L'Aigle d'Or, Mandragore, or Sapiens, because all of those games feature a ton of text... in French. Pretty much how many great games on PC-Engine are innnaccessible to non-Japanese audiences.

Other games are more acessible, but games like Billy La Banlieue or Marche à L'ombre are mostly fun or amusing to play if you know what they are referring to.

Edited December 14, 2016 by CatPix

[carlsson]

I've got a ton of genesis psu around here.

Assuming those are Genesis 1 power supplies, save those for when you import a ZX Spectrum. As noted, the GX4000 wants center positive polarity, while the Genesis and some others I mentioned have center negative polarity and likely would blow up something inside the console. You could cut the cord, flip it and solder it back on to permanently reverse polarity, but you might want a better solution.

 

But yes, low voltage DC is the same across the world, as long as you have a power supply with the appropriate voltage, correct polarity and plug and the power supply is rated for at least as many ampere as the device will draw. Save the step-ups for systems with built-in power supplies or very unusual voltages or plugs that you can't substitute easily.

Edited December 14, 2016 by carlsson

[kingrat101]

Ok, I've actually got a "powerline unviersal adapter" that alows me to select voltage and polarity, it's 600 mA, but I've seen multiple ones with like 1300 mA and so on. I think one of those will work. I currently use it for my Atari Lynx

[FOXx]

Hi!

alex_79 posted interesting answer that helped me understand differences between French and other versions. Since I have this cursed version, I'd like to know, is there any way (special cable, HW mod or anything else) that would output composite/RCA/“yellow plug” cable out of my French version GX4000? I can use Scart cable of course, but since all of my other consoles are connected via composite AV switch, I'd like to have GX4000 connected this way as well. 

 

Thank you!

[str0m]

One of these? Available at lots of places  https://www.retrogamingcables.co.uk/switched-scart-to-composite-video-adapter

 

Oh actually the post above suggests that won't work for you with the French one sorry

Edited August 6 by str0m
edit

[CatPix]

Since the French version doesn't output composite video, if you really need composite, you will need a RGB to composite video converter.

Another solution would be to replace the video output, unfortunately, the only way I see it is in the other way (adding RGB to UK consoles).

UK motherboard with a CXA1145 video encoder.

 

Comparing with a French motherboard, we can see Amstrad designed the board to accomodate both systems without different boards. it should be possible in your case to replace the 4 transistors by a CXA1145 chip. But there may be several other modification in part values here and there. It is possible to do it, but would require someone with resonnable skills in electronics and time to compare the French and UK versions.

[FOXx]

Understood. As I thought, way above my skills. Thank you for your help! So my only option is to hunt for some bare UK unit without accessories on eBay..

[CatPix]

Acquiring a RGB to composite converter may be cheaper than getting a motherboard, but in the long run it may be the better solution for you. And you can probably resell your RGB-only version in the US for people that already have a RGB setup.

[FOXx]

24 minutes ago, CatPix said:

And you can probably resell your RGB-only version in the US for people that already have a RGB setup.

I'm in EU, so I'll probably try local market. Although newer TVs got rid of most obsolete connectors, I think Scart is still somehow prevalent here and it may actually be easier and welcomed for some people to cennect the console this way. Once again, thank you!

[CatPix]

It would be easier perhaps for you to get a cheap non HD LCD to play with RGB? Unless you really need your current setup? GX4000 are quite expensive. Tho OFC if your RGB one works they you will resell it easily. You may even go on an Amstrad forum and try to make a trade?

[FOXx]

I have very good non HD LCD with tons of inputs (like, really surpising lot, from RF all the way to component, VGA and DVI). It's just that I want to have everything (14 consoles, not counting GX4000) connected via that one single AV switch. As stupid as it seems, I still think it's neat and easy to press a button on AV switch that cycle throug all AV input methods on TV. 

[Adamj91]

Would it be easier to mod a UK system to have csync like the French systems do? Would it even be possible?