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Old 18 October 2014, 15:46   #1
djkoelkast
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Arrow GBS-8220 (or GBS-8200) on Amiga gives purple hue

I've finally had some time to make a cable for my GBS-8220. I already tried the R G B S-way, but that wasn't any good. A lot of unsync, a lot of stuff that should not be on the screen.
So I went the YPbPr route as I found on this image:



The only difference I made was the GND: I didn't connect it to the RGBS-port but on the outside of the RCA-connectors that are connected to YPbPr, should work as well.

The problem is: my whole screen is pink/purple-ish.

This is what it looks like:



This is what it should look like: (this is connected through the A520 > composite > composite to VGA adapter)



The GBS-8220 is way sharper (and it should be) but way too pink/purple. What can I do to fix this?
The 3 adjusters on the GBS board don't do anything when on YPbPr, so that won't help. Maybe some different resistors?
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Old 18 October 2014, 16:38   #2
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Yes the different resistances can change the strength of each color, but unfortunately it can,t be a lot better screen, (also depends of the monitor model).
I remember my best setting lost a little the yellow,(lighter) and the white going a little pink..
Try to adjust the GBS and monitor from the menu for the best possible picture.
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Old 18 October 2014, 16:38   #3
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Your are feeding RGB into the component input of the board? I don't think thats ever going to work.

Isn't this the same effect anemos had with his experiment? A purple glow..

http://eab.abime.net/showthread.php?t=51326
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Old 18 October 2014, 16:48   #4
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yep this is my old (2010 wow!) Thread i explain there what is the best.. http://eab.abime.net/showthread.php?t=51326
Quote:
The only difference I made was the GND: I didn't connect it to the RGBS-port but on the outside of the RCA-connectors that are connected to YPbPr, should work as well.
yep. the Ground is no problem.
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Old 18 October 2014, 17:06   #5
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Quote:
Originally Posted by voyager View Post
Your are feeding RGB into the component input of the board? I don't think thats ever going to work.

Isn't this the same effect anemos had with his experiment? A purple glow..

http://eab.abime.net/showthread.php?t=51326
Hm ok, but using RGB + Sync is ugly as well. It does give the correct colors, but it gives all kinds of other stuff on the screen like white dots and noise.

I can't change the monitor settings, I also connect my A4000 with SD/FF and RTG to it (the monitor has 2 inputs) so I can't change over the thing every time I switch.

So I have to go with such thing I guess?

http://www.jaycar.co.uk/productView....b&form=KEYWORD
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Old 18 October 2014, 17:37   #6
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i have like this converter (RGB SCART to Component Video) and working well and stable whit GBS, corols is the right,but general quality is not the best of the best.. for example is a lower quality screening from RGB scart.
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Old 18 October 2014, 18:05   #7
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I don't need best of the best, when I want to do some fiddly stuff the Amiga native resolution isn't going to do it anyway. I can always switch to my A4000 and set it to the monitor's native resolution or whatever.
As long as it's a steady image with good colors and sharper than the composite option. It's mainly for playing games, serious stuff is happening on the A4000.
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Old 18 October 2014, 20:18   #8
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Quality is like composite to vga converter.. maybe a little better, the problem is the S**it GBS board.
I think better go for other solution
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Old 18 October 2014, 20:23   #9
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Quote:
Originally Posted by Anemos View Post
Quality is like composite to vga converter.. maybe a little better, the problem is the S**it GBS board.
I think better go for other solution
Well I have an Acorn Electron, a Sega Master System I and a TI99 4/A on the same GBS board and it's wonderful for those systems. The Acorn also had RGBS, the Amiga can do that too, but on the Amiga it's pretty useless.

How did you come up with the resistor values? Maybe other values help?

Last edited by djkoelkast; 18 October 2014 at 23:04.
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Old 19 October 2014, 07:55   #10
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Resistors is for balance color, you can change the value for each color for down-up level , example put bigger value to the RED, about 320 ohm,for level down.
You can using also on the Composite line with value 620~1Kohm.
For the Green line is good 68~ 100ohm.

Try this setting:
Blue - 320 ohm
Red - 512 ohm
Green - 68 ~ 75 ohm
CSync - 820~ 1K ohm

Important : resistor of the green must be connect after to Csync resistor (like as schematic)
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Old 20 October 2014, 19:05   #11
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I've ordered some differend resistors to test. But how did you come up with these values?
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Old 20 October 2014, 22:58   #12
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And why not use a cheap lcd tv? Every tv here still has a scart input? You can play with resistor types but the result will be more or less the same. Feeding rgb into a component input results in one missing color.
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Old 20 October 2014, 23:20   #13
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Quote:
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And why not use a cheap lcd tv? Every tv here still has a scart input? You can play with resistor types but the result will be more or less the same. Feeding rgb into a component input results in one missing color.
Because I also have my Amiga 4000 with RTG and FF/SD connected to it, it gives me a very high quality on this Eizo multiscan. But for games I'd like to use a plain 1.3 Amiga, but with the best possible quality.

So why bother making the image with what to connect how? (no offence and not to you as you didn't make it) If it will never work I should never use it.

Then try the RGBS option again I guess? The GBS board has an option for RGBS too.
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Old 21 October 2014, 12:17   #14
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So from what I understand, you also want to use your plain 1.3 Amiga on your Eizo multiscan. If so.. did you check the specs of your monitor? If it is a multiscan or multisync crt there is a possibility it can do 15KHz And it could work with the standard amiga output.

So..the GBS 8220 gives you sync problems. Did you use composiet sync of did you feed it H-V sync? You could try a sync stripper if you are using composiet sync.
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Old 21 October 2014, 12:26   #15
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Quote:
Originally Posted by voyager View Post
So from what I understand, you also want to use your plain 1.3 Amiga on your Eizo multiscan. If so.. did you check the specs of your monitor? If it is a multiscan or multisync crt there is a possibility it can do 15KHz And it could work with the standard amiga output.

So..the GBS 8220 gives you sync problems. Did you use composiet sync of did you feed it H-V sync? You could try a sync stripper if you are using composiet sync.
It has been a while ago I tried that route. (RGBS on GBS-8200 then, I use the 8200 for other purposes now, but it shouldn't make a difference really).
I went with the composite sync output. It worked but gave me all kinds of white specs on the screen, very annoying.

The monitor is an LCD monitor, it doesn't do 15KHz:

Analog: H: 27- 82 kHz, V: 50 85 Hz
Digital H: 27 64 kHz, V: 60 Hz (VGA Text: 70 Hz)
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Old 21 October 2014, 13:13   #16
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I was reading another topic here about the gbs, it does not like the H/V from the amiga it seems. I still think you could try a sync stripper. It removes the video from the composiet video signal.

But remember if you get it working the picture will have wave lines in it etc. Probably because the bad input filtering so you have to correct that etc. In the end just buy the indivision ECS and be done with it.
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Old 21 October 2014, 13:19   #17
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Problem with that is the price. The GBS board is about $20, the ECS is €99, so I try to get it as best as I can and the picture I have now is very stable, very sharp, only the colors are all over the place.
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Old 21 October 2014, 13:35   #18
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In component video:

Y PB PR is the analog video signal carried by component video cable in consumer electronics. The green cable carries Y, the blue cable carries PB and the red cable carries PR.

Sending a green signal would be redundant, as it can be derived using the blue, red and luma information.

The amiga gives you R G B - H/V sync or component sync.

Try the sync stripper.

Step for step instructions:

http://www.mmmonkey.co.uk/composite-...ripper-lm1881/


How did you power the board? from the Amiga?

Last edited by voyager; 21 October 2014 at 13:44.
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Old 21 October 2014, 13:54   #19
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That seems doable, thanks, I'll try that then!
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Old 21 October 2014, 14:01   #20
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First try to get a stable picture. If you get the white spots in the image report back and we will try to find out how we can fix that. Good luck.
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