Games Not Running! Screen Glitching! Why?

[+-^CrossBow^-]

36 minutes ago, Guitari said:

Thanks Saint. 

I wouldn't know about how the magic knight mod has been done as the creator of the mod did my installation. 

Yes the MD2 scart cable is what I'm using and I assume it's carrying RGB. It's a full pin scart plug. 

My 2009 flat screen has always been fine with every retro console I feed it.. And I have a lot of them! 

I've just tried to tune the analogue signal from the 7800's original RF out but it won't work so I think the modder has disabled it. 

I've been running the built in Asteroids (no cart inserted) and it doesn't crash/glitch the image to a black screen like the Game Drive does. 

Also tried without the seagull adapter and just the old fashioned joystick but still the screen glitches. I think the problem is my 7800 has a propensity for this intermittently, and the GD is just highlighting it on every boot. Whether the 7800 needs a service /recap etc I don't know. Maybe someone in the UK could take a look at it after I explore this upscaler option. 

 

EDIT - I can't spend $390 on the upscaler! But thanks for the recommendation. Inbuilt Asteroids has now been running for an hour and no glitches. I think the issue therefore must also be related to the cart slot.

Reach out to AA users @juansolo and @marauder666 to see if they can take a look at your 7800 for you. They are located in the UK and have a lot of experience with the 7800 and are very familiar with the quirks of the PAL consoles vs their NTSC counterparts.

 

[Guitari]

Thank you. I will. 

Update on the screen glitches... The power light dims to half illumination during the glitches. 

[juansolo]

Send it on over and we'll take a look, bob me a PM and we'll sort it out.

[SainT]

3 hours ago, Guitari said:

EDIT - I can't spend $390 on the upscaler! But thanks for the recommendation. Inbuilt Asteroids has now been running for an hour and no glitches. I think the issue therefore must also be related to the cart slot.

When you say crash to a black screen or crash the screen, what does that mean? Does it literally crash the console entirely? Ie. the game is no longer playing? Or does the screen get screwed, but if you power the TV off and on the picture comes back and the console is running? A photo or video may help figure out what’s going on.

 

But if commercial carts are doing the same over composite, then it does sound like a console issue rather than anything TV specific, especially if the inbuilt rom is ok. I had come to the conclusion from the description the TV was having a bit of a fit.

 

But do bear in mind, the 7800 is particularly bad when it comes to sync. Just because a different console of a similar era works on a TV fine, it doesn’t guarantee the 7800 will. The 7800 is a bit special with the way it fudges the CPU clock cycle length to access different areas of RAM and actually ends up causing jitter in the sync. It does just end up with how your TV deals with it. Mine refuses to show a picture at all, for example! Sony seem to be the pickiest of them all.

 

But that all said, if you can get your setup working properly let me know and I’ll see if I can add a screen position option in there for the AV port so you can center the screen. I think it should be possible.

[SainT]

3 hours ago, Guitari said:

The power light dims to half illumination during the glitches. 

Wowa, that doesn’t sound good. Failing regulator?

[Guitari]

That's all cool thanks Saint. It's Panasonic and only sometimes slightly glitchy with the Jaguar. 

I think it's the console at fault. The display just glitches or vanishes to black with the console still running. I think it's not happy with the GD rather than anything actually wrong with the GD. 

[Guitari]

3 hours ago, juansolo said:

Send it on over and we'll take a look, bob me a PM and we'll sort it out.

Thank you, will do. 

[Guitari]

16 hours ago, SainT said:

When you say crash to a black screen or crash the screen, what does that mean? Does it literally crash the console entirely? Ie. the game is no longer playing? Or does the screen get screwed, but if you power the TV off and on the picture comes back and the console is running? A photo or video may help figure out what’s going on.

 

But if commercial carts are doing the same over composite, then it does sound like a console issue rather than anything TV specific, especially if the inbuilt rom is ok. I had come to the conclusion from the description the TV was having a bit of a fit.

 

But do bear in mind, the 7800 is particularly bad when it comes to sync. Just because a different console of a similar era works on a TV fine, it doesn’t guarantee the 7800 will. The 7800 is a bit special with the way it fudges the CPU clock cycle length to access different areas of RAM and actually ends up causing jitter in the sync. It does just end up with how your TV deals with it. Mine refuses to show a picture at all, for example! Sony seem to be the pickiest of them all.

 

But that all said, if you can get your setup working properly let me know and I’ll see if I can add a screen position option in there for the AV port so you can center the screen. I think it should be possible.

Wanted to say - if you could add screen centering/positioning to your list for the future firmware updates, I think that would be pretty awesome and welcomed generally given the varying behaviours of flat screen TVs out there.

[Guitari]

18 hours ago, juansolo said:

Send it on over and we'll take a look, bob me a PM and we'll sort it out.

Just gonna do it a bit of further testing - with a different TV and will be in touch..

[Guitari]

Saint - 

I've just tested it with a slightly more modern flat screen TV and I have no image centering issues this time with the same RGB SCART cable. 

But the system is still semi powering down in the same way with the GD. 

Juansolo is going is going to look it over for me and do some fixes. I don't think the GD is at fault at all. 

 

[SainT]

Ok, sounds good! I thought when you said the power light was doing dim you meant on the 7800! 😆

[Overange]

Firstly the 7800GD is Great and well done its a very well designed product 

 

I have designed my own Composite/S-Video Output based on a design as per the link below and so far I can confirmed I have not seen/had any problems with running Video throught the 7800 using the 7800GD.

 

http://atari7800.org/7800mod/7800_mod.htm

 

As others report problems, I will try and recreate and report back, hopefully it may pin point where the problem is coming from.

 

 

I have noticed overscan in some games of which is commonly seen on Modern Displays, this begs the question, could you implement something like Myteks A8 UGV feature to remove the overscan?

 

https://ataribits.weebly.com/ugv.html

 

 

 

[SainT]

3 hours ago, Overange said:

I have noticed overscan in some games of which is commonly seen on Modern Displays, this begs the question, could you implement something like Myteks A8 UGV feature to remove the overscan?

 

https://ataribits.weebly.com/ugv.html

For the AV out port on the cart, yes, absolutely! I’ve been meaning to add a display end scanline option or similar as the display lists are often not terminated correctly and end up leaving random junk at the bottom of the screen. I may even be able to implement something such that Maria gets blank data when past a certain scanline, although this is tricker.

 

The biggest problem with adding any new features, however, is that the FPGA is very very full. So unfortunately I can’t make any promises about adding anything.

[FLEABttn]

 

Screen looks like this via the cartridge AV out. The 7800 has an S-video mod. Any ideas?

Edited July 28, 2023 by FLEABttn

[+-^CrossBow^-]

41 minutes ago, FLEABttn said:

 

Screen looks like this via the cartridge AV out. The 7800 has an S-video mod. Any ideas?

What is that supposed to be displaying or running?

 

Is this NTSC or PAL?

 

What cable from the AV out are your using with it specifically?

 

 

[FLEABttn]

25 minutes ago, -^CrossBow^- said:

What is that supposed to be displaying or running?

 

Is this NTSC or PAL?

 

What cable from the AV out are your using with it specifically?

 

 

This is supposed to be the main menu when the 7800 GameDrive boots up. It's a NTSC console running into a RetroTink 5x over an Insurrection Industries scart cable.

[+-^CrossBow^-]

1 hour ago, FLEABttn said:

This is supposed to be the main menu when the 7800 GameDrive boots up. It's a NTSC console running into a RetroTink 5x over an Insurrection Industries scart cable.

Thanks for providing that! Now does the game drive menu come up normally through your s-video output? Because it doesn't have to rely on the RGB output. So just to make sure the cart is working otherwise. Again, I'm not sure if you have done that but wanted to ask? Otherwise, as I'm still waiting on my 7800GD (sometime next week), I can only speculate until I can do some testing of my own.

 

[FLEABttn]

11 minutes ago, -^CrossBow^- said:

Thanks for providing that! Now does the game drive menu come up normally through your s-video output? Because it doesn't have to rely on the RGB output. So just to make sure the cart is working otherwise. Again, I'm not sure if you have done that but wanted to ask? Otherwise, as I'm still waiting on my 7800GD (sometime next week), I can only speculate until I can do some testing of my own.

 

It does not. It looks like this over s-video.

 

[SainT]

That’s definitely very broken, does the console run other cartridges?

 

Looking at the image, it does actually look like the menu, sort of. Does the initial coloured Atari logo appear when you boot with the GD inserted?

 

Best guess currently, if other carts are running, is the voltage regulator is on its way out as the GD will draw more current than a regular cart. Ballblazer (or other pokey cart) would be another useful one to test as this is the only commercial higher current draw cart.

 

I currently have a copy of Ballblazer on its way to me to compare the current draw of both carts. I’m guessing they will be quite similar.

Edited July 29, 2023 by SainT

[FLEABttn]

I have 2 7800 carts (Xevious and Asteroids) and both work. Also have 2600 ET and that works as well.

 

The initial Atari logo does not appear when I boot the GD.

 

When using s-video, the status screen of the retrotink 5x shows the input lines, input h-freq, input v-freq, and ADC clock as bouncing around.

 

The console was recapped a year or so ago but don't know if the regulator was replaced or not.

 

 

[Reaperman]

On 7/19/2023 at 3:26 AM, SainT said:

 

Incorrectly Installed AV Mod

If you are connecting your 7800 to a TV or monitor via a composite mod and are seeing very bad interference in the video signal when playing games which support some kind of external audio (POKEY, YM2151, COVOX, BupChip), then you will most likely have a wiring issue with AV mod install. 

 

Yup, this is me. I feel an unmodified spare console might be in my future, but I also have some scart cables on order to try out.

 

I also might revisit that av mod per the images. When I installed it (15-20 years ago) I seem recall it being a bit of a one-way trip, but there may be enough left in there to 'modify the modification.'

 

Anyway if anybody wants to see this kind of behavior in action, I have a quick unlisted vid below.

Otherwise, this is my big '7800GD weekend' so I have a lot more gaming to get back to.

[SainT]

I (hopefully) have a "fix" for this issue with the REV2 PCB, it will be tested shortly. While it's not strictly any fault of the 7800GD (it's an extremely bad idea to tie drivers together like this, the reason there is no issue with POKEY chips is because both TIA and POKEY are open drain, so this is safe), I'd still prefer people had the easiest experience possible.

[SainT]

1 hour ago, FLEABttn said:

I have 2 7800 carts (Xevious and Asteroids) and both work. Also have 2600 ET and that works as well.

 

The initial Atari logo does not appear when I boot the GD.

 

When using s-video, the status screen of the retrotink 5x shows the input lines, input h-freq, input v-freq, and ADC clock as bouncing around.

 

The console was recapped a year or so ago but don't know if the regulator was replaced or not.

It's really difficult to tell what's going on from one picture. Does the screen change at all when you try and boot with the GD? Or does it immediately go to that and just stay like it? The boot process for the GD would be the Atari logo, then the RetroHQ logo fades in, then back to black, then launches the game selection menu. Is there any indication of something like this happening?

 

The screen is obviously a mess, it looks like sync is all over the place. I don't know if the 7800 is executing any code at all from the cart, or if it's just hanging immediately and Maria is outputting junk.

 

My gut feeling currently is the regulator, especially given a recap, and the system is just hanging. Unfortunately with 30 year old hardware like the 7800, and a new piece of hardware like this, it takes a little while to figure out the root cause of symptoms like this. And this is not something I've seen before.

 

The other rather daft thing will be the edge connector. Despite the GD being new, it's always worth giving the edge connector a clean to rule out bad connections. Although in general a bad connection doesn't give that kind of screen as a result from my experience.

[+-^CrossBow^-]

55 minutes ago, Reaperman said:

Yup, this is me. I feel an unmodified spare console might be in my future, but I also have some scart cables on order to try out.

 

I also might revisit that av mod per the images. When I installed it (15-20 years ago) I seem recall it being a bit of a one-way trip, but there may be enough left in there to 'modify the modification.'

 

Anyway if anybody wants to see this kind of behavior in action, I have a quick unlisted vid below.

Otherwise, this is my big '7800GD weekend' so I have a lot more gaming to get back to.

Again, the way your audio is being handled in your current 7800 with that older AV mod is likely the issue and it can be corrected fairly easily. 

[Reaperman]

It looks like my mod is a vintagegamingandmore from probably ~2010. (install pic) (modboard closeup)

It gets the audio from a via (white wire in pic), and pokey audio joined in from the north end of a removed C10 way up by the cart slot.

 

Google & AA-searches seems to indicate a lot of barebones mods of the era did this. I probably have commando volume mixing issues, and seem to recall that being the case. "oh well, it's just one game and it looks so much better"

 

So, checking my understanding here, and looking up crossbow's UAV install guide, (and several mentions on this thread), my easy option is to lift R5+R6's north end and connect them both to the positive end of a 10uf cap (like this one?) and just run the other leg to the audio jacks. No point in saving the RF audio, since I cut off the video portion of it already, it seems.

 

This sounds super-doable, unless my removed-c10 is on the wrong side of r5.

Edited July 29, 2023 by Reaperman