RGB Color problem on Amiga 1200

[lolof]

Hello,

I am posting here because I have bad color issue with my Amiga 1200 on RGB out and I have no idea how to solve this problem. My MB is a 1D4.
It shows the colors wrong, instead of blue it shows light green.
The mother board has new caps, so that's not the problem.
I tried with different TV, monitor and cable. Always the same result.
The composite video out works normally, this happen only on RGB.
My MB is pal and I tried on Pal TV and monitor is well set to RGB.
If I start the Amiga without HD and nothing connected, I am not able to show the kickstart menu. If I connect the HD, it goes in a green workbench. If I boot from a disc game, it goes also on the green colors, I can see red color but nothing in blue. I suppose that there is something wrong with the blue line in the RGB signal.
Has someone experience with this to help me to fix my MB.
Thanks in advance.

[kipper2k]

Originally Posted by lolof

Hello,

I am posting here because I have bad color issue with my Amiga 1200 on RGB out and I have no idea how to solve this problem. My MB is a 1D4.
It shows the colors wrong, instead of blue it shows light green.
The mother board has new caps, so that's not the problem.
I tried with different TV, monitor and cable. Always the same result.
The composite video out works normally, this happen only on RGB.
My MB is pal and I tried on Pal TV and monitor is well set to RGB.
If I start the Amiga without HD and nothing connected, I am not able to show the kickstart menu. If I connect the HD, it goes in a green workbench. If I boot from a disc game, it goes also on the green colors, I can see red color but nothing in blue. I suppose that there is something wrong with the blue line in the RGB signal.
Has someone experience with this to help me to fix my MB.
Thanks in advance.

i would guess that you have a bad resistor on the 23 pin output from your Amiga. (guessing the resistor tied to pin 5 output on the 23 pin RGB output). Composite is working and that is fed from the CXA1145 chip so the Amiga RGB output from the video chip appears to be good.

Use an ohm meter and compare the values of the resistors feeding pin 3, 4, and 5 to see if any of them are cracked/burnt. the resistor values should be the same. You can also try taking a really close up picture on a camera to see if any appear to be cracked etc, could also be one of the small ceramic caps in the same area too so could take a while to find the culprit

btw, when the HDD is disconnected don't forget if using KS 3.1 that it can take up to 30 seconds if no HDD or floppy is connected so be patient waiting for the KS screen