AV Equipment, Reviews
SCART Switch Manual Push Button 5 Way Review
This often unbranded switch goes by several names, including “Nedis Silver Scart Switch Box 5 Way”, “5 Way SCART Selector SLX Gold”, “Professional 4 Way Scart Switching Box” and probably several others. The review here also applies to similar models with 3 or 4 inputs and/or phono/RCA connectors. Switches like this are easily identified by the black or silver case and push button switches. To select an input you press in the button, to deselect it you simply release the button. Like most other budget switches, output is via a moulded cable with a SCART plug on the end.
Brightness/noise test:- Failed. Significant noise added to the picture, picture significantly dimmed.
Isolation test:- Failed, deselected inputs were not isolated from current input at all.
Conclusion:- Cheap and nasty. Not suitable for videogamers or anyone concerned with picture quality.
I just re-read the main article and I noticed that you wrote that all the pins should be isolated. Moreover, I noticed in practice that inputs C and D on my switch actually have some crosstalk/isolation issues. I never noticed it before because I was only using the first three inputs. So I better look for a better switch. Too bad all of the good ones seems to be out of stock.
To perform the test I simply connect two consoles at the same time, power them both on and check what the picture does. Yes, it is important to isolate the connections, if you do not, you may find your SNES powers itself on while you are using your Megadrive, for instance, due to so much voltage leaking across to the wrong pins. That’s not likely to do your vintage hardware a lot of good.
So your test is the same I did when I bought the push button switch. And it passed it! I don’t see any noise or brightness issue comparing to the console connected straight through the upscaler, even though I don’t have a capture card to make a side by side comparison, so I may be missing something.
Regarding isolation test, I have a Mega Drive on Input A, a SNES on Input B and a PS One on Input C. I can turn on the other two while playing the first one without any change on the image, even though the grounds are not isolated as I found out using the multimeter today.
So I guess that even though isolation problems on RGB or voltage pins are easily detectable through picture noise, non-isolated ground pins won’t be detected by this method. I wouldn’t bet that other manual switches (like Hama) actually isolate the 20 pins. They may be isolating only the “active” pins as well.
Put the SNES in input C and turn the MD and PS1 on. You may find your SNES mysteriously powering itself up.
I tried that. Nothing happened.
But I already saw the behavior you described. It happens when all the pins (specially pins 8 and 16 that carry the highest tensions) are non-isolated, because the voltage output by the other consoles would flow back to SNES and power it on.
In this switch (at least in the one I got) these pins are isolated when the SNES push button is off, so it won’t power on by itself. Even though the grounds are not isolated, they don’t carry enough power to turn SNES on or even cause any noise in the Mega Drive or Playstation One picture.
My point is, if it is important to isolate the ground pins as well, we need to test the switches with a multimeter (the mechanic ones, I don’t think it’s possible on electronic ones), because there is no visible degratation in picture when only the ground pins are not isolated.
By the way, I’m thinking about trying on this switch: http://goo.gl/7skVXe – It seems well built, at least from the outside, and it is not very expensive.
I have one of these and until I find your article I was believing it was good enough.
I made a review (in portuguese) with some pictures here a year and a half ago when I bought it: http://goo.gl/ZVzHyi
I never noticed any difference between using it and connecting the consoles directly to my upscaler. But after reading your article I’ve decided to test which pins are actually being connected/disconnected as I press the buttons. This is what I found:
Pins 1, 3, 10, 12, 14, and 19 are always isolated no matter the switches.
Apparently these are output and/or non-used pins in my scenario. So it is ok.
Pins 4, 5, 9, 13, 17, and 18 are always connected no matter the switches.
They are all ground pins.
Pins 2, 6, 7, 8, 11, 15, 16, and 20 are the ones which the switch actually works on.
These are audio inputs, RGB inputs and the pins that carry some tension.
So, my questions are:
1) Does it matter that the ground pins are not isolated?
2) How do you conduct the isolation test? Does the better switches actually isolate the grounds?