From: Daniel Kahlin (tlr_at_stacken.kth.se)
Date: 2005-11-26 16:33:52
On Sat, 26 Nov 2005, Ullrich von Bassewitz wrote: > On Fri, Nov 25, 2005 at 10:51:52AM -0500, Golan Klinger wrote: >> Does your unit suffer from the colour problems being described in >> comp.sys.cbm and on the DTV hacking message board? People seem quite >> agitated over the problem. > * The resistor arrays used to mix chroma and luma bits have different > values. I cannot currently tell which one is which, but one uses 2K/1K as > in the schematics, the other uses 680/330. Luma uses 680/330. Luma0 -> R14 Luma1 -> R18 Luma2 -> R22 Luma3 -> R12 or R26 Sync -> R26 or R12 Chroma0 -> R15 Chroma1 -> R19 Chroma2 -> R23 Chroma3 -> R27 > * Even more important: The active output mixer/buffer stage (Q2) is > completely missing. The output using the 2K/1K array goes almost straight > to the video output, while the one that uses the 680/330 array is sent > via a low pass/band pass filter similar to the one in the schematics to > the video jack. > > The next step should be to identify the chroma and lumina outputs. Once this > is known, one could replace the existing circuit by an active mixer/buffer as > it is shown in the schematics and check if this fixes the color issue. > Unfortunately, I'm not brave enough to remove the die cover. Does anybody know > how to do this without destroying the chip? I was brave enough to look a my photo and think. ;) Quite funny that we came to a similar conclusion at the same time! :) Look here for my findings and a great shot of the video mixer: http://jledger.proboards19.com/index.cgi?action=display&board=dtvhacking&thread=1132824828&page=3 /Daniel Kahlin Message was sent through the cbm-hackers mailing list
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