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Apple IIGS Video Problem

iigs video problem apple composite lcd

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#1 Le Derp OFFLINE  

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Posted Mon Aug 1, 2016 9:20 PM

After pulling my Apple IIGS out of the attic, I plugged it in to my modern LCD TV via composite. However, upon boot up, the screen is garbled and jumpy. If i wiggle/twist the RCA connector at the IIGS end, i can fix the garbled video and jumpiness, however the colors are all wrong, as in they look very deadened/muted. Medium blue appears as a dark blueish grey, dark red looks like brown, yellow looks very faded, etc. Is this caused by the failure of a certain chip, should I replace the capacitors, or what?

 

EDIT: I should also add that if I flip the switch on the back, and turn it on again, I have to wiggle the RCA cable all over again for a while to get the image to work.

When viewing text, there are also several pink/green artifacts. Knowing that it is an Apple II on a color display, this could happen, but I just wanted to put it in here to be safe.


Edited by Le Derp, Mon Aug 1, 2016 9:29 PM.


#2 david__schmidt OFFLINE  

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Posted Tue Aug 2, 2016 8:29 AM

Have you tried any other video device with this machine, preferably a retro CRT-based one?  Some LCDs simply don't like the A2 video signal.



#3 R.Cade OFFLINE  

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Posted Tue Aug 2, 2016 8:37 AM

Apple II color relies on signal trickery, i.e. NTSC artifacts, which modern displays may not handle properly.

 

It really was done by exploiting the way the signal was interpreted by the television.


Edited by R.Cade, Tue Aug 2, 2016 8:39 AM.


#4 Le Derp OFFLINE  

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Posted Tue Aug 2, 2016 10:04 AM

Thanks! Probably shouldn't have thrown out my last CRT last week. On the other hand, would the need to wiggle the connector be due to wear and tear of the connector, or corrosion? And why do I need to mess with the connector every time I toggle the power switch, even if I don't move the connector at all?



#5 Keatah OFFLINE  

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Posted Tue Aug 2, 2016 11:54 AM

..would the need to wiggle the connector be due to wear and tear of the connector, or corrosion?

 

Likely all, wear and tear, and corrosion due to age.

 

 

And why do I need to mess with the connector every time I toggle the power switch, even if I don't move the connector at all?

 

 

Because RF frequencies can arc across microscopic cracks in solder joints. And if the connector doesn't have good grounding you're going to get all sorts of noise introduced into the signal.

 

1st thing to do is clean up the connector and make sure all solder joints are good and solid. And that the connector has a good firm mechanical fit. Make sure it's clean with no residue. And that it has a bit of TV tuner cleaner or contact cleaner on it.

 

Troubleshoot this one step at a time. From front to back.

 

---

 

Once you get that done and done with. We move on to seeing if your TV set is compatible with the Apple's signal. Many modern sets have difficulty with non-standard video. Many micros of the 70's and 80's took a lot of liberty with the video specification, some even relied on trickery/artifacting to get colors.



#6 Le Derp OFFLINE  

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Posted Tue Aug 2, 2016 5:43 PM

Should I worry about damaging the machine by turning it on due to the aforementioned arcing RF frequencies and questionable grounding?



#7 Keatah OFFLINE  

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Posted Tue Aug 2, 2016 5:55 PM

No. But it is something that should be eliminated as a cause.



#8 Le Derp OFFLINE  

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Posted Thu Aug 4, 2016 11:35 AM

I've cleaned the connector and made sure that it is solid.

 

Sorry if this is a newbish question, but as for solder joints, should I check the soldering on the connector first? If the connector is fine, what should I try after that?

 

After cleaning the RCA jack, the video has improved somewhat. (less interference, flickering)



#9 Le Derp OFFLINE  

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Posted Thu Aug 4, 2016 3:02 PM

One thing I should probably note is that the deadened colors are only a problem when in the 'text' mode, e.g. when at the BASIC prompt, booting up, in the Control Panel, etc. When the colors are deadened, the most obvious problems are the background and border colors. After switching to lo-res graphics mode or hi-res, the problems go away.

 

EDIT: One more side note: On occasion while turning the connector to make the video work, the image will be clear while scrolling vertically, sort of like when you plug PAL devices into NTSC tv's, just much slower scrolling. Is it possible some of the issues are related to bad timing of vertical sync?


Edited by Le Derp, Thu Aug 4, 2016 3:14 PM.


#10 R.Cade OFFLINE  

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Posted Thu Aug 4, 2016 3:07 PM

Post a picture of the color problem. I think I had one that did this, and I'm trying to remember if it was a bad setting in the control panel or something easy like that, or if it was a problem with a certain monitor...


Edited by R.Cade, Thu Aug 4, 2016 3:07 PM.


#11 Le Derp OFFLINE  

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Posted Thu Aug 4, 2016 3:35 PM

https://www.dropbox...._video.jpg?dl=1

 

The image being reversed is simply my camera.

 

Also excuse the temporary setup, the other TV is occupied right now. :)

 

The color for border and background says 'Medium Blue' however as you can see it doesn't appear that way.


Edited by Le Derp, Thu Aug 4, 2016 3:35 PM.


#12 R.Cade OFFLINE  

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Posted Thu Aug 4, 2016 5:03 PM

That looks normal to me...

#13 Le Derp OFFLINE  

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Posted Thu Aug 4, 2016 5:35 PM

So this is normal functioning for composite video? Well derp.

 

Guess I should get an RGB -> Component adapter or one of the CRT's that are compatible with the IIGS.

 

As for the scrolling/jumping video at startup, after cleaning the connector 3 times with isopropyl alcohol, the jumping seems to be reduced. Where should I go from here?



#14 gozar OFFLINE  

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Posted Thu Aug 4, 2016 6:27 PM

I can't remember, can you switch PAL/NTSC is the control panel?


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#15 Le Derp OFFLINE  

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Posted Thu Aug 4, 2016 6:46 PM

Right now I have it set on 60hz, and my TV is an NTSC TV.



#16 Keatah OFFLINE  

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Posted Fri Aug 5, 2016 2:53 AM

Medium-blue means this:

 

https://www.google.c...SUyB_EQ_AUIBygC



#17 The Usotsuki OFFLINE  

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Posted Fri Aug 5, 2016 5:06 AM

When you hit Opt-Ctrl-Reset, it asks "enter control panel", "set system defaults and 60 Hz" (NTSC), "set system defaults and 50 Hz" (PAL), "continue rebooting the system"



#18 Le Derp OFFLINE  

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Posted Fri Aug 5, 2016 8:54 AM

Medium-blue means this:

 

https://www.google.c...SUyB_EQ_AUIBygC

 

Except when viewing on my TV via composite, it appears far different from that, much more washed out.

 

Should I try a CRT on composite, or get one of the IIGS RGB -> Component Video adapters?



#19 Keatah OFFLINE  

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Posted Fri Aug 5, 2016 9:33 AM

Either/or. See what happens!



#20 R.Cade OFFLINE  

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Posted Fri Aug 5, 2016 9:40 AM

Here is my similar problem from years ago...

 

http://www.applefrit...m/?q=node/23892





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