Main > Monitor/Video Forum
Video amp (RGBs) to boost SCART to arcade monitor
arfink:
as long as your sync is in range and your signal voltage isn't too high, it should just work.
arcadeswede:
--- Quote from: arfink on May 13, 2020, 10:32:59 am ---as long as your sync is in range and your signal voltage isn't too high, it should just work.
--- End quote ---
What? Doesn't make sense. According to this page, specs for arcade vs scart looks like this:
--- Quote ---Arcade video (standard resolution)
Video amplitude: 2-5Vpp
Video DC offset: yes, as much as a volt or two
Video input impedance: 1k-10k
separate horizontal and vertical sync (most of the time)
sync polarity negative (most of the time)
SCART video (RGB SCART)
Video amplitude: 0.7Vpp
Video DC offset: no DC offset, AC coupled
Video input impedance: 75
sync signals stripped from Composite video (CVBS)
sync polarity negative
--- End quote ---
Maybe sync will be fine but voltages for the SCART signals are way to weak, hence the need for amplification.
Just to be clear, I'm talking about connecting a console with RGB SCART to a arcade monitor, not arcade to TV (aka Supergun).
arfink:
Right, I understand that. I'm just saying, if you want an image and you don't want to blow up your monitor, just make sure you have the right sync frequency + polarity (usually, composite negative sync, 15khz) and don't exceed 4-5vpp for your video signal. You can amplify up to that point as needed/desired. If you go over on the shmups forums in their RGB modding thread, you can see that people have committed worse abominations in RGB signal land and been fine.
buttersoft:
Some few arcade monitors will work fin with 0.7Vp-p RGB, most won't be able to boost it and will need an amp. Ultimarc's one will work fine, or if you want to build one a THS7374 is as good, and a THS7314 or 7316 almost as good.
arcadeswede:
--- Quote from: buttersoft on May 14, 2020, 02:48:50 am ---Some few arcade monitors will work fin with 0.7Vp-p RGB, most won't be able to boost it and will need an amp. Ultimarc's one will work fine, or if you want to build one a THS7374 is as good, and a THS7314 or 7316 almost as good.
--- End quote ---
Ok, good to know!
According to the datasheet of the 7374, it only has a gain of x2 (6db), which equals to 0.7Vpp x 2 = 1.4Vpp. Which is not really enough ???
I found a THS7375 with a 15db gain (around x5.6) which equals to 0.7Vpp x 5.6 = 3.92Vpp. That should be good enough, right?
Btw, does these signals need to be AC coupled going into these?