You may have noticed in my two part post on getting my IIgs up and running that I was using a nice, modern LCD monitor with that vintage, retro computer. How did I do that? Well, some of the guys over at the Facebook Group Apple IIgs Enthusiasts (https://www.facebook.com/groups/1780661448825195) came up with the idea that if we can easily convert the IIgs RGB signal to SCART (an analog HD video format common in most places other than the US), why can’t we use this SCART->HDMI adapter (http://a.co/8NhC6MW) to convert the SCART to HDMI, opening up an entire universe of cheap, readily available LCD monitors and TVs for use with your Apple IIgs.
I ordered the RGB cable from Retrocables (http://retrocables.es/tienda/index.php?id_product=607&controller=product&id_lang=1) and the SCART->HDMI Adapter from the above mentioned link at Amazon. I received the Amazon order the next day. After a grueling 7 weeks to wait for shipping from Spain, the cable arrived. I put everything together and without any need for any configuration at all, the screen lit up!
Keep in mind, this solution is not *perfect* so much as it is one of the best available when you do not have a true IIgs RGB CRT monitor to use. 95% of the time, it is perfect. The other 5% of the time is when I get this sort of electrical interference that causes some sort of distortion of certain shades of blue and grey colors. Usually, this is most visible on the GS/OS main screen because of the default background, shaded drive icons and shaded scroll bars are the perfect blue and grey colors for setting it off. Once I open up any app, the distortion is not visible at all, even if it has very similar colors to that background. I believe it is the method that Apple used for shading these GUI items that is causing the issue. I am still trying to get my hands on an original AppleColor RGB Monitor ASM6014 and then I will see if this works better that the original. I suspect not.
I believe that the original work on this modern video solution goes back to some work that was done a bit before I was involved. This website has all of the details behind it all: http://www.apple2faq.com/knowledgebase/apple-iigs-modern-video-options/