Hi,
Quote:
Originally Posted by RedskullDC
Hi Higgy, et al.
Apologies if this has already been posted somewhere here.
Ewan of http://microbeetechnology.com.au/ has come up with a fix for the white spots on the GBS boards.
His explanation:
"The SDRAM interface from the TV5725 scaler chip on the board has no damping resistors in the clock & control lines
and fails to calibrate the timing of the interface properly as a result. It is marginal and causes bad screen refresh data.
As such it took some time to track this down as the cause.
There is a track to be cut and the resistor (SMD 0603 size, or 1608 metric) gets fitted across the cut. Then the capacitor is soldered to the ground end
of a nearby bypass cap & the free end linked to the SDRAM side of the resistor that was fitted across the track cut. It is not very elegant, but it works & cures the video noise totally."
Some pics of the mod:
http://www.microbeetechnology.com.au...200Mod-pt1.JPG
http://www.microbeetechnology.com.au...200Mod-pt2.JPG
http://www.microbeetechnology.com.au...200Mod-pt3.JPG
Have done the mod to my GBS board, and the difference is noticeable.
Hope this helps,
Red |
I measured my V4 GBS-8200 board today using a fast oscilloscope. The SDRAM clock signal did not violate the electrical limits of the Hynix SDRAM. On the GBS-8200 V4 there is no need to apply this modification.
If I can get my hands on a GBS-8220 V3 board, I'll repeat the test and advise on suitability.
Ian