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Amstrad GX4000 on an NTSC TV - Need Help


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No I use this one and have had no issues yet

 

I use it with my Videopac 7200, VG 5000 and CoCo3

 

I have one of those (or something that looks exactly identical) for secondary SCART connections. It's not bad. The image looks good, anyway. The only complaint I really have is that when the console switches resolutions (a hassle with Saturn games that go between 480i and 240p) the screen blanks and then when it comes back the new resolution is displayed for something like 20 seconds in the corner.

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I have one of those (or something that looks exactly identical) for secondary SCART connections. It's not bad. The image looks good, anyway. The only complaint I really have is that when the console switches resolutions (a hassle with Saturn games that go between 480i and 240p) the screen blanks and then when it comes back the new resolution is displayed for something like 20 seconds in the corner.

Yes it does do that. Doesnt bother me tho as its only for a few seconds and by the time my game is ready its gone anyway

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What is the lag like? I suppose for systems like the Videopac and VG-5000 that usually is not a matter. No idea about CoCo 3 games. Amstrad games perhaps have a little more action, not to mention newer systems like the Saturn.

 

Also the older formats rarely have any alternative video modes to switch between, so for that purpose it might not be an issue.

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Well, that could be a problem for the Amstrad.

Many Amstrad games use the hi res mod for the HUD and Low-res for the game field.

No idea how that translate as far as the analog signal goes, if everything is "encapsuled" within the hi res mod or if the Gate Array does a trick of changing resolution mid-picture.

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What is the lag like? I suppose for systems like the Videopac and VG-5000 that usually is not a matter. No idea about CoCo 3 games. Amstrad games perhaps have a little more action, not to mention newer systems like the Saturn.

 

Also the older formats rarely have any alternative video modes to switch between, so for that purpose it might not be an issue.

Ive not noticed any lag in anything Ive played so far. On the Videopac it actually seems it goes a bit faster on the TV via the adapter than on the built in screen lol

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  • 1 year later...

It's time to bump this thread because I need help too. I am not using a Framemeister but instead a multi-system CRT TV (yeah, I got lucky and found one locally) and I cannot get the GX4000 to display at all. I've actually tried two different consoles now and I have a PAL Megadrive which displays fine of the TV even playing Super Skidmarks which is known to be tough to play outside of PAL land. All I've been using is RF for now, the manual says channel 36 but I still get nothing on the multi-system TV, just some static when the power is turned on. The TV has S-Video and AV only, no component. What are my options and what am I doing wrong?

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Well, first, are you sure that your GX 4000 is working? Unfortunately it's extremely easy to fry a GX 4000 ?

Since you mention RF out, I suppose you have a UK system. You should have black and white composite video on the sync pin out of the A/V port as well as sound, that would rule out a console malfunction.

Also It's not impossible, if it's a UK system, that the RF signal is on the VHF band.

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Wow, your TV has channels?  Mine has presets that can each be assigned by doing a slow scan across the entire frequency bands.  They likely did it that way because different broadcasting systems have different channel frequencies.

 

It's also possible that your TV does this too, and your "36" is not actually tuned to UHF 36 yet.

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I just ordered a Scart to RCA cable, it looks like it's broadcasting on an RF signal out of the TV's range. Hopefully the AV cable will solve my problems and I can start enjoying this game system for what it is. BTW, are multi system TVs really that hard to find? I never hear about anyone talking about them at all and everyone is buying Framemeisters or other converters and everyone I talk to has trouble getting them to work properly too.

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Depedns what kind of multistandard you talk about. I think even in the Us, NTSC/PAL TVs are common enough by now, enve tho with composite going away, (apparently?) it won't be a thing fror much longer.

Now, finding a multistandard RF able TV? That's another story completely.

Even with using service menus, on my most recent CRT TVs, I never found a large recent one that accepted NTSC-M standard, only the NTSC 4.43 used in some South American countries.

I'm not sure about the US, but finding a TV that can tune PAL B/G would be a though thing... and other norms? even less likely, as you would need a PAL I compatible TV if your GX-4000 was from the UK. The difference is in sound tuning, that mean you could have a good picture but no sound, or a poor/no picture but sound.

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Yeah.  My Hitachi TV is RF capable on at least NTSC and PAL, but doesn't seem to support SECAM over RF.  You can connect it by AV though.  The TV was manufactured around 1990, and Hitachi basically has no documentation left for it anymore--I asked them.  I have seen TVs that claim to accept multiple standards, but it's typically only through the AV or digital inputs.  Some PC TV cards will tune multiple standard channels though.  Back in the PCI days, Hauppauge made many styles.

 

On my TV, you first bring up the menu, then choose "PRESETS".  Then you have the option to fine tune an existing channel or search for new ones.  Whichever you choose, the next thing that comes up is the sound carrier frequency.  For most of Europe's PAL, it would be 6.5MHz.  After that it shows a segmented bar across the screen and the band value.  You then pick your channel, then use one button to seek/step forward while a different one will seek/step backward.  Once the channel is tuned in, you can choose a different channel or exit the menu.

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6 hours ago, vintagegamecrazy said:

I just ordered a Scart to RCA cable, it looks like it's broadcasting on an RF signal out of the TV's range. Hopefully the AV cable will solve my problems and I can start enjoying this game system for what it is.

 

I am sorry -it won't work, unless that cable has some electronics inside ?

 

SCART is a kind of connector that houses several video signals: RGB, Composite and S-video (not Components or high definition though). The problem is that the GX4000 only outputs RGB video throught SCART!. I have double-checked it before writing, and it seems that

a) there is no GX4000 model that provides composite video

b) you have few options -and some of them are commented in the link.

 

What I would do if I were in America and could not find a TV with SCART inputs: first, I would try to find a monitor with any kind of RGB connectors. An old CGA display would need some kind of adapter, so I would look for an Amiga monitor instead.

 

Then, if it the RGB option is very expensive or I could not find any, I would go for the composite video. I would take it from the input of the RF modulator, inside the GX4000, as explained in the link. But it is a sub-optimal solution in my opinion, so in the end I would go back to the first option and would try to hack any CRT TV set to inject RGB in some point (it would require extensive electronics knowledge). After some electric shocks, I would reconsider importing a proper RGB monitor at any cost.

 

My third choice would be to convert the signal for a modern display (HDMI, Components). IMO, this kind of adapters/scalers doesn't do a good job, it's is the worst option, I don't like the result at all ?

Edited by deepfb
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40 minutes ago, deepfb said:

there is no GX4000 model that provides composite video

Hm, the documents (Amstrad user manual no less) I linked to on the previous page seems to indicate otherwise, that UK models of the GX-4000 have composite video on the SCART connector while French units only have composite sync? But I never tried in real life, so that might be inaccurate info I gathered.

Edited by carlsson
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21 minutes ago, carlsson said:

Hm, the documents (Amstrad user manual no less) I linked to on the previous page seems to indicate otherwise, that UK models of the GX-4000 have composite video on the SCART connector while French units only have composite sync? But I never tried in real life, so that might be inaccurate info I gathered.

I checked the CPCWiki forum because I know there are two different models, with or without modulator, and I wasn't sure about it. I don't have a UK model at hand (only Spanish/French), and they said so, that GX4000 only outputs RGB... but you may be right! Since the composite signal is present before the modulator in the UK/RF model, it doesn't make sense not wiring it to the SCART connector.

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5 hours ago, deepfb said:

I checked the CPCWiki forum because I know there are two different models, with or without modulator, and I wasn't sure about it. I don't have a UK model at hand (only Spanish/French), and they said so, that GX4000 only outputs RGB... but you may be right! Since the composite signal is present before the modulator in the UK/RF model, it doesn't make sense not wiring it to the SCART connector.

Well it would, if you remove the modulator!

Why do you need composite? To feed the RF modulator. Drop the modulator, and all you need is to wire the RGB output of your video chip straight (well possibly with amplification, alright) directly to the RGB connector.

Going composite isn't required in ay moment. the C-sync signal is send into the SCART via the composite wire because composite signal always include C-sync, but in RGB mode, a SCART-able TV or monitor won't check for a video signal, only for a sync signal, so you don't even need it here either.

At best, like for the CPC original computers, you might have a luma signal, so you would have a picture, but permanently black and white.

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Yeah, double check that your tuner is in the right mode as it could easily be overlooked.

 

When it comes to internal modding, I'm reminded of the old ZX Spectrum et. al trick where you simply take the composite video lead going into the RF modulator, bypass the RF circuitry and reuse the RCA jack. Minimal intrusion, and you'd get a composite video signal without going through the SCART connector. Of course you'd need to route sound from elsewhere, e.g. the SCART connector anyway so this would only be useful on French/Spanish models that don't offer composite video through SCART.

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1 hour ago, CatPix said:

At best, like for the CPC original computers, you might have a luma signal

Per page 11 of the manual, the 8-pin monitor jack has luminance (or perhaps they mean intensity for an RGBI signal?) while the SCART obviously doesn't have it because it is wired for RGB, whereas pin 20 would be in conflict for either composite video/sync or luminance, and pin 15 would be in conflict for either red or chrominance.

 

http://cpctech.cpc-live.com/docs/manual/gx4000.pdf

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The 8 pins monitor have luma as it's the schematics for the older CP models, and luma was used for the green monitor.

I was wrong tho as I see that it had separate pins for sync and luma.

Obviously if luma and sync are separated, it's gonna conflict (unless you use the "upgraded" SCART connection for S-Video) because SCART expect sync and composite video on the same pin. (or sync and luma, as in, video signal without composite color signal)

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