English Amiga Board - View Single Post - GBS-8220, 23DB Connectors and Leads

Johan1973 · 18 April 2014, 01:15

Another day of investigating this turned up this;

1. The first GBS 8220 I got and has been doing the main testing on is faulty. I have talked to the seller and confirmed this, it is behaving in a way that it should not be doing.

2. The IC I used for the build was a bit wonky, after having tested another IC I could easily determine that. Seems it inverted the signal in first stage, but both second stages on the csync was not reinverted. And that caused loads of problems.

3. The Ferrite bead remove 90% or so of the white dot problem. However, the RGB lines are very sensitive to noise (in the input of the GBS 8220). And here is where I finish my day on this subject today. Tomorrow I will investigate what I can do about it.

http://sharesend.com/wws9jej2

The above is an archive with schematic, and pictures of how to build this circuit into the 23 Pin DSUB. The Ferrite bead are in the vga connector (not shown on photos. Since I plan on adding something on that end to deal with the RGB issue as described above).

18 April 2014, 01:15	#78
Johan1973 Registered User Join Date: Dec 2012 Location: Sweden Posts: 125	Another day of investigating this turned up this; 1. The first GBS 8220 I got and has been doing the main testing on is faulty. I have talked to the seller and confirmed this, it is behaving in a way that it should not be doing. 2. The IC I used for the build was a bit wonky, after having tested another IC I could easily determine that. Seems it inverted the signal in first stage, but both second stages on the csync was not reinverted. And that caused loads of problems. 3. The Ferrite bead remove 90% or so of the white dot problem. However, the RGB lines are very sensitive to noise (in the input of the GBS 8220). And here is where I finish my day on this subject today. Tomorrow I will investigate what I can do about it. http://sharesend.com/wws9jej2 The above is an archive with schematic, and pictures of how to build this circuit into the 23 Pin DSUB. The Ferrite bead are in the vga connector (not shown on photos. Since I plan on adding something on that end to deal with the RGB issue as described above).