AliExpress RetroTink Equivalent 2x Scaler with HDMI Output

[+MrFish]

On 5/19/2024 at 3:50 PM, mytek said:

Tried Kangaroo straight over S-Video on my VIZIO monitor and red lines are still quite visible. I also did a quick standard definition capture to make sure this was attributable to my monitor, and it wasn't.

OK, interesting, because I was beginning to think it was your monitor. So, it's just the output of your machine or combination of that and the cables you're using.

 

On 5/19/2024 at 3:50 PM, mytek said:

Funny thing is, when I looked at examples on YouTube they were all over the map as far as color was concerned. But I did find one that is very similar to what I'm seeing (3rd one down).

That doesn't surprise me at all; because I'd guess a lot of videos to be using emulation, which is going to give an array of palettes used, and most likely some NTSC/PAL color differences.

 

[+mytek]

I got my 2nd RetroScaler 2x in the mail, and it checks out fine, duplicating what I saw with the first one.

 

However I started to see some odd things that were not attributable to the Retroscaler itself, but were very visible via the S-Video input on my VIZO monitor.

 

 

I'll call them ghost highlights, and they were on the edges of certain color transitions.

 

I've been running these tests with my 576NUCplus4 system, and started to suspect something wrong with it, and not the monitor. So I pulled out a 65XE that had a UGV installed and saw no color ghost effects when using it to look at the same image. Then going back to the NUC, I put its crystal oscillator on a scope and discovered the issue - non symmetry. Notice that the bottom line of the trace is wider than the top.

 

This is not something I ever checked, or should I say "paid attention to" when I was developing the NUC, but it's quite important as I found out.

 

 

So I made a couple of mods to the oscillator section in the NUC and got the resultant image as seen via the Retroscaler 2x feeding into the VIZIO's HDMI input. The Retroscaler just keeps looking better and better as the quality of the S-Video signal improves.

 

EDIT: Top to bottom gradient due to my monitor's uneven back light (it's a 2007 era monitor).

 

And here's the scope image now showing a 50/50 duty cycle after the mods. Its not a sine wave like what the stock Atari has, but sufficient for what the GTIA needs to see.

EDIT: with the added capacitor it does begin the transformation from digital to sine wave, and does seem to make the clock more acceptable. I still need to test with a PAL crystal to make sure that I didn't cause any oscillator start-up issues.

 

 

So the modification consists of one added resistor for the symmetry adjustment, and one capacitor to smooth the leading edge. A pretty easy mod.

 

 

While I was at it, I also revisited the resistor DAC values, as well as the color coupling on both the NUC and the UGV board to bring them a bit more into alignment with the video standard. So eventually I'll be posting details about that in a separate thread.

 

EDIT: And I went back and ran that Kangaroo game again after performing this mod, and I'm pleased to say all the strange color ghosting disappeared from it as well.

 

And this came out pretty well via the Retroscaler 2x (very difficult to capture real life image quality with digital camera - looks way better in person and you can see the gray squares all way down to black).

[_The Doctor__]

Great findings! Good work!

This might be a good idea to compare against other video mods as they all seem to slightly inform and borrow off of each other over the years. If it turns out to solve issues on other mods, it might need to be addressed by making sure it's prominently addressed and noted in each mod (checking symmetry and smoothness). Most of the time it's been written off as cable/monitor/machines design issues and dropped or forgotten, but almost always from or in a machine with video mods and possible cable issue threads.

7 hours ago, mytek said:

I got my 2nd RetroScaler 2x in the mail, and it checks out fine, duplicating what I saw with the first one.

 

However I started to see some odd things that were not attributable to the Retroscaler itself, but were very visible via the S-Video input on my VIZO monitor.

 

 

I'll call them ghost highlights, and they were on the edges of certain color transitions.

 

I've been running these tests with my 576NUCplus4 system, and started to suspect something wrong with it, and not the monitor. So I pulled out a 65XE that had a UGV installed and saw no color ghost effects when using it to look at the same image. Then going back to the NUC, I put its crystal oscillator on a scope and discovered the issue - non symmetry. Notice that the bottom line of the trace is wider than the top.

 

This is not something I ever checked, or should I say "paid attention to" when I was developing the NUC, but it's quite important as I found out.

 

 

So I made a couple of mods to the oscillator section in the NUC and got the resultant image as seen via the Retroscaler 2x feeding into the VIZIO's HDMI input. The Retroscaler just keeps looking better and better as the quality of the S-Video signal improves.

 

EDIT: Top to bottom gradient due to my monitor's uneven back light (it's a 2007 era monitor).

 

And here's the scope image now showing a 50/50 duty cycle after the mods. Its not a sine wave like what the stock Atari has, but sufficient for what the GTIA needs to see.

 

 

So the modification consists of one added resistor for the symmetry adjustment, and one capacitor to smooth the leading edge. A pretty easy mod.

 

 

While I was at it, I also revisited the resistor DAC values, as well as the color coupling on both the NUC and the UGV board to bring them a bit more into alignment with the video standard. So eventually I'll be posting details about that in a separate thread.

 

EDIT: And I went back and ran that Kangaroo game again after performing this mod, and I'm pleased to say all the strange color ghosting disappeared from it as well.

 

And this came out pretty well via the Retroscaler 2x (very difficult to capture real life image quality with digital camera - looks way better in person and you can see the gray squares all way down to black).

 

Edited May 28 by _The Doctor__

[+mytek]

3 hours ago, _The Doctor__ said:

This might be a good idea to compare against other video mods as they all seem to slightly inform and borrow off of each other over the years.

Good point, but in this case it had nothing to do with the video side of things other than the symptoms that focused attention on the real problem. For strictly video related upgrades and mods, they get a free ticket. But for alternative motherboards, the oscillator sections should be scrutinized to see if the duty cycle is indeed 50/50. As for stock machines and specifically the motherboards, in most cases they should already have a 50/50 duty cycle sine wave oscillator, although perhaps not quite perfect (see example circuits and notes below).

 

EDIT: Here's a download link to "2 Stupid Dogs" that does a good job at revealing any oscillator symmetry issues in a visual way.

 

 

The 1088XEL shares a similar sine wave two transistor oscillator with the 800XL.

 

 

 

 

In fact the only difference is to one of the pull-up resistors, with the 800XL being 470 ohm and the 1088XEL being 430 ohm. And the use of two different PNP type transistors, although that really didn't influence the operating characteristics between the two oscillator circuits that I recall. However the resistor change does, and in the case of the 1088XEL it improved the Duty-Cycle, bringing it much closer to 50/50 - all thanks to a discussion I had with Bob Woolley @bob1200xl back when the XEL project began.

 

BTW, the oscillator symmetry problem is likely going to be the same for the 1088XLD, which also incorporates a simple schmitt trigger inverter oscillator.

Edited May 28 by mytek
added note about the 1088XLD

[+MrFish]

13 hours ago, mytek said:

EDIT: And I went back and ran that Kangaroo game again after performing this mod, and I'm pleased to say all the strange color ghosting disappeared from it as well.

That's good news.

 

[+mytek]

Kangaroo via the RetroScaler 2x is now working quite well after adjusting the Duty-Cycle on the NUC's crystal oscillator.

 

[+mytek]

So after all my fiddling, what do I think of the RetroScaler 2x?

 

For NTSC it works fantastic, and appears to be every bit as good as a RetroTink 2x in this regard, except for some random flicker and fuzziness concerning resolution improvement tricks (480i mode). Since a predominant amount of games and applications don't use this mode, I personally don't consider it a great loss, but that's me. Being able to output HDMI with integrated stereo audio for around $35, makes this well worth the investment. Of course the HDMI quality is directly tied to the quality of the AV going in, so it's highly recommended that something like the UAV, UGV, or Spectre is already in play, and that the S-Video input be used. This would also be the case with the RetroTink as well.

 

And lastly FlickerTerm does appear to work well, but it does have noticeable flicker, which would also be the case with going straight into the S-Video input on the monitor. Disclaimer: I don't use this program myself, and only gave it a quick review, so you're mileage may vary.

 

For PAL I can't recommend it

[+MrFish]

On 5/31/2024 at 2:38 PM, mytek said:

So after all my fiddling, what do I think of the RetroScaler 2x?

Did you ever test out the composite input, to see how well it does with some games that use artifacting (Ultima IV, Night Mission Pinball, etc.)?

 

[+mytek]

10 minutes ago, MrFish said:

Did you ever test out the composite input, to see how well it does with some games that use artifacting (Ultima IV, Night Mission Pinball, etc.)?

 

No I didn't, but I will try that when I get a chance, and report back on the results here.

[+mytek]

Here's what Night Mission Pinball looks like via the RetroScaler 2x's HDMI using the Composite input.

 

 

When I ran it through the composite input on my VIZIO monitor it looked nearly identical. Color saturation looks even better with my own 2 eyes, and got slightly muted when taking a picture of the screen.

 

EDIT: When I went back to the S-Video input I could still see a little bit of color leaking through, but this entirely went away when I disconnected the composite input, giving me a nice gray scale image. So the built-in video switch obviously doesn't have very good isolation.

 

EDIT2: Awww correction. When I first cycled the video switch, it had both composite and S-Video selected at the same time, but a few more presses of the selection button and then it only showed S-Video and this worked properly without color bleed even when I reconnected the composite cable. Very odd that they would have it set-up to do that. However when the source has color, you still don't want the composite cable plugged in at the same time as the S-Video because it causes evenly spaced vertical lines.

[+MrFish]

9 hours ago, mytek said:

Here's what Night Mission Pinball looks like via the RetroScaler 2x's HDMI using the Composite input.

Thanks for checking it out. I expected it to work, since the RetroTink handles artifacting fine too, and they're similar type of devices.

 

9 hours ago, mytek said:

EDIT: When I went back to the S-Video input I could still see a little bit of color leaking through, but this entirely went away when I disconnected the composite input, giving me a nice gray scale image. So the built-in video switch obviously doesn't have very good isolation.

 

EDIT2: Awww correction. When I first cycled the video switch, it had both composite and S-Video selected at the same time, but a few more presses of the selection button and then it only showed S-Video and this worked properly without color bleed even when I reconnected the composite cable. Very odd that they would have it set-up to do that. However when the source has color, you still don't want the composite cable plugged in at the same time as the S-Video because it causes evenly spaced vertical lines.

Maybe a feature than a bug, giving some variations on the two types of video effects/options.

 

[+mytek]

4 hours ago, MrFish said:

Maybe a feature than a bug, giving some variations on the two types of video effects/options.

Yeah I'll have to read the manual it came with to see if they left any clues, and perhaps revisit this.

[+mytek]

I was playing around with my 576NUCplus4 tonight and had it hooked up to an HDMI monitor via the RetroScaler 2X at my vacation home. I'm using a more modern HDTV on this go around which is a compact 21" model (Element). But I don't have the remote to access the menu and adjust things, so it's stuck in wide screen mode. However when I booted up The Last Word the wider screen really wasn't an issue, and in fact the software generated 80 column screen text looked very nice!

 

So I took a picture of it, which turned out remarkably well, and not too much different than what my eyes were seeing.

 

 

And because of @flashjazzcat's excellent programming skills, this would actually be a very usable word processor. Too bad the Atari didn't have a larger redefinable character set, because all this is missing is WYSIWYG bold, underline, and italics.

[+Larry]

I've got to ask... What is the 576NUCplus4?  I looked at your web page, and searched here, but see no explanations.  Maybe 4 different add-ons to the +? 

 

Also, with respect to clarity, is the picture through the RetroScaler visually equivalent to a hookup to a direct S-Video connection.  Or maybe slightly worse or slightly better?  (Hard to imagine better, but possible I guess because of the improvements in TV's/monitors.)

 

Colecovision (CVNUC+) -- sweet!   

[+mytek]

3 hours ago, Larry said:

I've got to ask... What is the 576NUCplus4?  I looked at your web page, and searched here, but see no explanations.  Maybe 4 different add-ons to the +?

Yes it's a new expansion system for the 576NUC+ that adds 4 new simultaneous abilities to the base system. It expands the RAM from 576K up to 1088K, and includes the A8PicoCart, R-Time 8, and either the SDrive-ng or FujiNet (one at a time), with SDrive being the default -and- FujiNet as a plug-in optional module.

 

EDIT: Every feature is controlled by the PS/2 keyboard - there are no physical switches other than what the keyboard brings to the table. And every operation is controlled instantly, without a need to traverse additional menus.

 

Currently there's probably a bit more information in my blog about it.

 

And here's a Block Diagram that covers it fairly well...

 

 

- Michael

[+mytek]

3 hours ago, Larry said:

Also, with respect to clarity, is the picture through the RetroScaler visually equivalent to a hookup to a direct S-Video connection.  Or maybe slightly worse or slightly better?  (Hard to imagine better, but possible I guess because of the improvements in TV's/monitors.)

It's usually the same quality if the TV/monitor has both S-Video and HDMI inputs. Although I have run across monitors that have shitty S-Video yet get good HDMI results. And because it all comes down to starting with excellent S-Video output to yield good HDMI results through the converter, UAV or equivalent video is essential. The 576NUC+'s video is in this league.

[bfollowell]

I just ordered one of these for use with my NTSC A8s. I'm looking forward to checking it out. I appreciate all of the discussion here.