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Old 27 November 2014, 09:52   #122
RedskullDC
Digital Corruption
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Join Date: Jan 2007
Location: Sydney/Australia
Age: 53
Posts: 300
Hi Higgy, et al.
Quote:
Originally Posted by Higgy View Post
Fingers crossed speckles are a thing of the past now.
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
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