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Author Topic: RGB to VGA Adapter + GBS 8200  (Read 4348 times)

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Offline AmigamiaTopic starter

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RGB to VGA Adapter + GBS 8200
« on: September 13, 2015, 01:49:12 PM »
I have had much tribulations with this darn video port. Here is the setup:

One of these cheesy adapter:

http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=183

Connected on the RGB port and VGA cable going to:

https://www.google.com/search?q=GBS+8200&ie=utf-8&oe=utf-8

Powered by a 10V power adapter and connected to a LCD screen via another VGA cable.

The GBS 8200 comes on fine and I can see the menu settings but when I power the Amiga 500, the power lights just alternates between bright and dim green. No video signal. If I unplug the VGA cable going from the Amiga to the GBS8200, The Amiga 500 powers on OK ( I hear the floppy clicking). I have tried 2 different amiga 500 and two different VGA cables already. Either the wiring in the RGB<->VGA adapter is wrong or the GBS8200 is shorting something somehow. Has anyone had any success with this setup? Any clue?
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Offline AmigamiaTopic starter

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Re: RGB to VGA Adapter + GBS 8200
« Reply #1 on: September 14, 2015, 12:23:37 AM »
Quote from: AmmoJammo;795596
The GBS runs off 5 volt, not 10.

This shouldn't cause the A500 not to boot up, unless the VGA adapter you have (which has a small circuit in it) is connecting the "5volts" from the GBS board, back to the A500's video port.


Well, The GBS says DC 5V-12V and it does work at 10V. However, 10V may be an issue?

 

I have opened the RGB<>VGA adapter and connected the wires individually according to the instructions on the page below but still the same problem.

http://www.retro-commodore.eu/2014/03/11/cheap-rgb-to-vga-converter-amiga/
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Offline AmigamiaTopic starter

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Re: RGB to VGA Adapter + GBS 8200
« Reply #2 on: September 14, 2015, 04:37:53 PM »
Quote from: AmmoJammo;795607
got a picture of the cable you made up?

so with the GBS plugged in to the Amiga, either via the vga connector, or the posts on the board, the Amiga doesn't boot up?


As soon as I  go home I will take some snaps. Yes, that is correct: When I have the VGA cable or the posts connected to the GBS, the Amiga powers on but the Power LED flashes between dim/bright and I never hear the floppy drive trying to boot. I got a hold of a 5V 2A Power adapter. Will try it this evening and report..
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Offline AmigamiaTopic starter

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Re: RGB to VGA Adapter + GBS 8200
« Reply #3 on: September 20, 2015, 11:46:29 PM »
Got some time to tinker with it again and here is what I found thus far. If I plug all in, the Amiga 500 doesn't seem to boot where the floppy drive makes the usual sound.

If I unplug the VGA adapter cable from the GBS 8200, the Amiga boots. I can then plug the VGA adapter on the GBS 8200 but still no signal. However, if I switch the display settings between 640x480 & 800x600 the Workbench 1.3 insert disk hand flickers on the screen with a purple background and then it goes to "No Signal". See images.

The RGB<>VGA Adapter is wired as follows:

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Offline AmigamiaTopic starter

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Re: RGB to VGA Adapter + GBS 8200
« Reply #4 on: September 21, 2015, 01:57:50 AM »
SoaB!!

Small progress. The Sync cable (Grey) was in the wrong pin. I had to move it down one pin because I am using a DB25 cut to fit a DB23 (AmigaKit provided). So now I can see the picture but it has a purple tint to it. I have checked the RGB and the GND and they seem to be in the right hole. I have checked 2 amigas and same prob. Monitor works on other PC. Any Clue??
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Offline AmigamiaTopic starter

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Re: RGB to VGA Adapter + GBS 8200
« Reply #5 on: September 21, 2015, 04:45:41 PM »
Quote from: AmmoJammo;796028
Without seeing pictures of where the wires are soldered, I can't really comment.


I'll try to take a close up picture. I doubt it will help because the DB25 (Cut to be a DB23) has a ribbon cable connected and I have the wires that came with the GBS 8200 connected to the other ends of the ribbon. I have traced and retraced it several times but I can't seem to find anything mismatching other than the sync.

According to other forum posts, the purple hue is due to lack/weak green signal. I know the green is there and wired but I also read that I need to adjust the potentiometers by the RGB signal. I haven't tried that yet but I will soon, while I have the image on the screen.
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Offline AmigamiaTopic starter

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Re: RGB to VGA Adapter + GBS 8200
« Reply #6 on: December 06, 2015, 02:26:05 PM »
So I managed to adjust and get the right colors but the quality is what it is. For $21 I can't complain though.

Since the board came without a case, I asked a friend of mine with a 3D printer to attempt in making one. A couple days later, here comes the result:

http://www.thingiverse.com/thing:1177258






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