Atari 520 ST video issues

[Oldskool]

Thanks again for the help.
These demos indeed work and I see a full screen (So I need a newer glue?):

demo.PNG (1.49 MiB) Viewed 3442 times

demo2.PNG (1.04 MiB) Viewed 3442 times

demo3.PNG (1.36 MiB) Viewed 3442 times

[stephen_usher]

Most of my STs are fine, but one shows regular vertical bars, especially in green and blue.

Is that image taken using a TFT? If not, do those bars show on a CRT? Esp. the SC1224?
I‘m asking because the lines I see on several machines are mostly grey (a change in overall brightness).

It's on a TFT but the lines are consistent irrespective of whether it's directly into the SCART on the TV or via the OSSC and they move with the image as I adjust the OSSC and the display moves across the screen or stretches/shrinks so it's not a TFT artifact, especially as the OSSC is upscaling 4x.

[tin]

It's on a TFT but the lines are consistent irrespective of whether it's directly into the SCART on the TV or via the OSSC and they move with the image as I adjust the OSSC and the display moves across the screen or stretches/shrinks so it's not a TFT artifact, especially as the OSSC is upscaling 4x.

Well, I suspect that CRTs (which like the SC1224 are using 75 ohms impendance) to have an impact on the STs RGB lines and/or act as a... well „filter“ through this. A TV should have 75 ohms, too, so that‘s indeed strange.

If the device connected to the ST wasn‘t involved aka had no impact on the STs RGB lines, I‘d suspect to see stripes on an SC1224, too (which do disappear there with my tested machines).

[exxos]

Just measure the rgb lines on the monitor and check resistance to gnd. My monitor measure 75R to gnd. If they not there, then easy enough to add them inside the scart connector..

Even while it can contribute to issues, using vsync and Hsync instead of composite sync can cause jail bar issues. That's been mentioned many times on here.

A lot of the problems is just noise on the RGB lines being generated on the motherboard itself. The shifters output isn't perfect, the RGB drivers amplify the noise..

CRTs naturally dither such issues out. Some people prefer the CRT image as you don't get sharp pixels and outlines etc.

[tin]

Thanks again for the help.
These demos indeed work and I see a full screen (So I need a newer glue?)

Thanks for testing - since those screens work and the Glue is the only chip issuing the DE signal (aka telling the shifter if it should display border or image data) it‘s probably a fair test to switch that Glue with another one. At least I can‘t see how your addons could disturb how DE is issued - at least in a way that mimics short top border behaviour.
It‘s not defective, but since many newer demos unfortunately aren‘t tested against/don‘t support short top border Glues, an newer Glue is probably the way to go.

If you have another ST, you could just switch Glues. If not, PM me, we can see (depending on where you‘re at) if we just swap Glues (aka I send you a tested long top border one and you send me yours for my tests). I really was lead to believe only -20 Glues had the old DE logic.

EDIT: I can confirm btw that all of your examples in the first post except Pang won‘t open the bottom border correctly on this old Glue machine I‘ve set up now. Which Pang version did you use?

[Oldskool]

Hi Tin,

I tried various Pang versions from the internet. They all seem to have the issue. (garbage at the bottom of the screen, Sometimes I even got part the Ocean logo from the intro at the bottom).
The game works fine and only the game screen is affected.
I'm in the Netherlands. If you are not in the Neighbourhood I will just try to source a newer Glue somewhere.

Hereby a picture of Pang with the Ocean logo at the bottom (flickering/ ocean logo and some tiles)

pangocean.PNG (1.39 MiB) Viewed 3392 times

[tin]

(garbage at the bottom of the screen, Sometimes I even got part the Ocean logo from the intro at the bottom).
The game works fine and only the game screen is affected.

For some reason I checked for a non-open bottom border - but this is sth different (which I‘ve seen on the old Glue machine too).
But it‘s probably unrelated and stems from the fact, that back when this was created no display would show lines that far down the screen. So the developers probably never saw that garbage/and or the crackers didn‘t.

So it‘s safe to say from your examples, that my short border Glue machine and your machine behave the same regarding bottom border opening.

[Oldskool]

Thanks for all the tips. Ordered a new glue. Will let you know the result.

[Oldskool]

Finally received a new glue chip.
It fixed all my issues.
So the Pang game and all the Demos now work great.
My old chip will be send to Germany (Tin).

[exxos]