Review of Arcade Forge's UMSA (Ultimate SCART Adapter)

[Paradroid]

Took me a while to finally get around to this but I'm happy to report that Arcade Forge's latest gadget is an absolute ripper! Check out my review here.

[mazinger-z]

Nice review!
Just one thing: could you please see how it performs with interlaced screens? I have built an awful lot of different circuits for mixing the sync signals, but didn't get satisfying interlaced screens on my arcade monitor and my SCART TV. Some lines are thicker than others and the result is acceptable but ugly. I know the monitor is able to display perfectly balanced interlaced screens because I used a DTT decoder (connected through an LM1881 sync separator) when I was repairing it, to display various test screens, video clips and television. The TV set also works nicely with interlaced screens coming from other sources.
The problem isn't likely to depend on the video card, as I used about 5 different cards, and furthermore, everything was perfect on my Microvitec M1438 monitor, that has separate sync inputs (in fact it has a true VGA connector).
Could you please also post a couple of big pictures of both sides of the adapter? 

[Paradroid]

Interesting points. I'll look into these on the coming weekend...

I have noticed that interlaced modes vary quite a bit between TVs. My old Blaupunkt (with Grundig chassis) is very nice in interlaced mode. My other Grundig (much newer) looks awful interlaced. Just plain ugly. Loewes have some fancy "smoothing" circuitry that makes interlaced look more refined. I never thought that the sync combining circuit might affect this. As I said, I'll look into it for you.

Can definitely post some large top/bottom pictures of the UMSA itself.

[MonMotha]

Both specifics about your video timing (number of blanked lines, length of vsync, relative number of blanked lines before vs. after vsync, etc.) and the way you generate the composite sync can affect performance of interlaced video.  Digital sync separation methods are usually a bit pickier than the analog timers of yore.  They need to "detect" that the signal is interlaced, otherwise you end up with it treating the video as progressive and a VERY jittery display.  The upside is that they're a fair bit more accurate and can handle much shorter sync pulses to start with.  It's also generally very important with modern designs to make sure that the sync format (horizontal offset from vertical) is correct to properly signal interlaced video to the monitor.

Generally, the "correct" thing to do is output the exact timings specified by your old regional analog TV standard and XOR the two sync signals (having the same polarity) together.  If you want negative sync, invert one of the incoming signals or invert the result.  While this may not get the equalization/serration quite right, it seems to make most monitors happy.

Some of the "passive sync combiners" that use only resistors or diodes and resistors can exhibit somewhat weird behavior.  The "resistors only" method (or just tying your two sync outputs together) will actually give you a tri-level output that most purely analog designs are OK with but can upset the later digital designs.  Some of the diode based designs work well enough while others omit serration/equalization pulses during vsync and can be problematic on analog (and some digital) designs, especially when using interlaced video.

The more you stray from "standard" TV timings, the more likely you are to need to play with things, and YMMV, of course.  Sometimes, the thing to do seems to be to throw all the electronics out the window and just twist your horizontal and vertical sync wires together (preferably with a couple of low value resistors just in case your video source doesn't have any series resistance!).

[SailorSat]

everything was perfect on my Microvitec M1438 monitor, that has separate sync inputs (in fact it has a true VGA connector).

It also works with CSync on the HSync pin and VSync left disconnected

[bencao74]

Hey,

 thanks a lot for this great review. Glad you like the work on this device 

Bye

Jochen

[maiki]

I have posted this comment on your blog as well...

Could you please post pictures of more stressful video modes, especially those that run at 240 scanlines at 60 Hz? Games like R-Type Leo (Irem, 1992)! Rainbow Islands is not the best example to test since it is only using 224 scanlines / 60 Hz, but I can clearly see you are already in trouble provided the portion of the screen is not visible! I mean, such a product can only be great if the TV is able to handle the video modes 100%.

Also, does that device send the TV automatically into RGB mode or do you have to switch it manually? Very important as well...

[Paradroid]

Could you please post pictures of more stressful video modes, especially those that run at 240 scanlines at 60 Hz?

Yes. Will do! Won't be a problem, I play those kind of games all the time.

Rainbow Islands is not the best example to test since it is only using 224 scanlines / 60 Hz, but I can clearly see you are already in trouble provided the portion of the screen is not visible!

Nah. There's no problem. I just adjusted the overscan the way I like it. Maybe others would do it differently but I like the sides cleanly clipped and the top and bottom only just showing some black space in between the raster and mask.

I mean, such a product can only be great if the TV is able to handle the video modes 100%.

Correct, kind of. The product can be great without the TV being great. However, you are right to say that although the UMSA solves the hassle of having to build a VGA to SCART cable, the TV you run will still be a limiting factor when it comes to the range of video modes available.

Also, does that device send the TV automatically into RGB mode or do you have to switch it manually? Very important as well...

Yes, the UMSA switches to RGB mode for you. That's what external power adapter is all about.

[bencao74]

UMSA needs a power supply of 5V and generates the 12V for AV mode switching internally. Blanking is set as well.

[Paradroid]

Hey guys!

Just letting you all know that I recently updated my UMSA review with additional screenshots of this VGA to SCART adapter working with a wider variety of televisions. It performed equally well across all the TVs tested and I'm yet to experience any kind of hiccup with this great gadget! Still highly recommended!

UMSA Review (with updated screenshots)

Cheers,
Dale

[Sam250]

Accidently brought this without the 5v adaptor. Contacted Arcade Forge but also found a 5v adaptor in a drawer in my kitchen. Not sure what it is for (perhaps a phone). Would this be suitable and safe to use instead of the €6 "simple 5v PSU" Arcade Forge supplies? This is what my plug reads on the label:

AC/DC ADAPTOR
[model number]
INPUT: 100-240V-50/60Hz 40mA
OUTPUT: 5V [symbol with — over ...] 100mA

And to anyone that can describe to me which of that information is important in working out the suitability of a power plug: I would be most thankful to hear it!

[lordsnipe]

Hey Paradroid,

Received my UMSA and having an issue.

Does the UMSA require 5V in the centre pin or on the outside? The website doesn't specify.

Also, how much current is required?

I have wired a USB cable to barrel tip connector with positive on the ring (negative on the centre pin), but I don't get a picture. The VGA cable plugged into a monitor directly results in no picture so I'm confident the PC is outputting 15khz.

Is there a LED indicator that the UMSA is receiving power?

[apfelanni]

use an external 5 volt dc psu or solder a molex to get the current from your computer . center pins 2+3 of a molex are ground for maybe 3 dekades .  get a 3 $ external psu and ure done . on arcadeforge website you find some pcis , 12 and 5 volt on the molex are printed on the pcb . ask bencao if the power from usb will do the job.

i have some of these power supplys in use :

http://www.pollin.de/shop/dt/MDcxOTQ2OTk-/Stromversorgung/Netzgeraete/Steckernetzgeraete/Stecker_Schaltnetzteil_KSUFB0500050D1EU.html

[lordsnipe]

Thanks .. Jochen from ArcadeForge also mentioned the molex header on the PCB. I've soldered a molex cable onto it and is now working. I would've thought USB would have enough current to power it up.

[Minwah]

This looks like a very nice device. My question is, is the quality actually better than just using a VGA > Scart cable? I don't know the technicalities of what the board does but I can't imagine much better quality than what I have seen using just a cable.

I do however understand that this is a nice way to hook things up, without the need to make a cable. I hate making cables that use connectors like Scart / VGA.

[lordsnipe]

Same quality.. No fuss

[Minwah]

Same quality.. No fuss

Ok, thanks!

[apfelanni]

the benefit is that its plug n play and u can use high quality cables in  length u need. i prefer short vga cables and highend scart cables with good shielding and a plug which doesnt fell apart after 4 weeks . with something like this u wont have to worry bout shielding or loose connectors .

http://www.ebay.de/itm/HAMA-SCARTKABEL-Black-Stream-0-75m-21-polig-vergoldet-Scart-Kabel-1-95-Versand-/281161663281?pt=DE_Computing_Monitor_AV_Kabel_Adapter&hash=item41768a8331

[haynor666]

They could solder molex socket default or put USB connector so it would be easier to connect 5V from PC. My VGA connector on ATI 4350 can be disconnected from bracket and together with UMSA hide in PC box. Since I won't messing myself with soldering additional lines to UMSA I'm forced to use external PSU (another cable into my computer).

They even didn't specify what exactly PSU is needed (plug dimension, polarity, minimum power)

What exactly molex we need to solder? Standard for HDD, DVDs or floppy connector?

[apfelanni]

i mentioned a suitable psu 6 posts up . 5,2 / 2,2 mm plug , + on the inner pin , the current doesnt  matter ... and  a classic 4 pin molex like used on harddisks will do the trick . or get a ready made cable with the miniplug ( its often use on cheap china electrics like amps ) and take the 5 volt from whereever u want .