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15kHz passthrough CRT protection dongle - sale thread

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buttersoft:
Only one LED at a time should be lit! Either the green one (15Khz ok) or the red one (sync blocked).

The dongle only works one way, so the male VGA side is the input. Or did you mean you were using a normal male-male VGA cable, and then a female-female adapter, then into the male VGA of the dongle?

Zebidee:

--- Quote from: buttersoft on June 08, 2023, 02:04:55 am ---Only one LED at a time should be lit! Either the green one (15Khz ok) or the red one (sync blocked).

--- End quote ---


I looked a bit closer - because the LEDs point downwards on my PCs, and the cards are near the bottom already, it is actually hard to get a good look without craning my neck about. So I turned the PC upside-down!

Turns out you are right, of course - but it LOOKS like the red LED is lit at the same time as the other one (yellow?) if you view it from the side. The light from the yellow LED shines through the dome of the red LED, making it look like it is lit.

I've attached pics to demonstrate. I changed nothing between the pics except my viewing angle. The red LED seems lit and seems to get redder as you move around to see the yellow light shining directly through it

I wrapped the dongle in some paper tape because the 3D printed housing was starting to come apart a bit too easily.


--- Quote ---It only works one way, so the male VGA side of the dongle is the input. Or did you mean you were using a normal male-male VGA cable, and then a female-female adapter, then into the male VGA of the dongle?

--- End quote ---


Oh gosh you are right - I was using a VGA male-male cable and turning the dongle around without even realising it. I think I need to write IN / OUT on it  :laugh2:

One reason why I wanted to use a cable was to see the LEDs better.

Will see if I can find my VGA gender-benders and give that a go :D

buttersoft:
I'll dedicate this post to the dongle's compatibility with other devices.

Extron 190F
Downstream there's no 5V, though you could probably break it out and try.
Upstream - the specs of the 190F say it takes RGBS input. I think this must mean with c-sync at 5V? Lowering the 1k resistor on the c-sync output to ~950k everything works. HOWEVER, the extron must have DDSP sync processing ON. With sync processing off, i think the Extron is trying to grab sync from the colour lines (it also takes RGsB/RsGsBs input). Which means that at 31kHz, while the c-sync line itself is effectively set to ground (with some MHz hum) the Extron is outputting an unclean 31kHz-ish signal that is half noise, which i wouldn't count as protecting your monitor properly.
I can modify a dongle if you are interested, probably with an 820R resistor. But you MUST remember to set DDSP on (dipswitch off). Most monitors should not be affected by this change, saving that sync processing causes a tiny in itself, but it's not going to fix pre-existing issues.

Other Extron devices
Untested. See above on the 190F, though there are no guarantees your device will work the same.

 

bestb484:
Post redacted

PL1:

--- Quote from: bestb484 on September 28, 2023, 11:43:34 pm ---For some reason I am not able to DM you, perhaps because this is my first post. :)

--- End quote ---
Now that your first post is approved, you should be able to send Private Messages.   :cheers:

You might want to remove the email address from your post to avoid unwanted attention from auto-scraping spammers.   ;)


Scott

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