Re: Serious Val Problem with Panasonic TH-42PX75U plasma

Re: Serious Val Problem with Panasonic TH-42PX75U plasma

Home Forums General Chit Chat and Other Stuff Serious Val Problem with Panasonic TH-42PX75U plasma Re: Serious Val Problem with Panasonic TH-42PX75U plasma


It was obvious I couldn’t do measurements while in the Service Menu the first time I did an exploratory measurement in Service Menu mode (I’d already measured the same thing before I went in to Service Menu mode), so, yes, I was already doing the measurements outside the Service Menu mode and only going into Service Menu to make changes to cuts/gains.

That method is what produced the measured Gammas of 1.65 for Custom mode and 1.85 for Cinema mode. As mentioned in the first post, I have very low post-calibration dEs from 10% to 100% in both Cinema and Custom which is reflected in nice flat temperature graphs and RGB graphs. I just couldn’t get Gamma anywhere close to 2.2-2.5. At least not while minimizing that goofy floating black problem (black level jumps up very noticeably if 100% white window luminance is set higher than 29 fL). The owner of the display, being the tweak he is, did his own calibration in January and measured 2.5 Gamma, but he had bad floating black issues and his RGB and temp graphs were far worse than what I left him with. His Gamma graph showed the 3 colors separating as luminance increased (the 3 colors were not tracking the same gamma curve). And his 10% step was very red which was incredibly obvious in movies. I’m beginning to think my “perfect settings” for the gray scale and elimination of the floating black problem put the display into a place where it simply can’t do Gamma. The owner specifically asked me (before the calibration) to eliminate the floating blacks and the bad red tint he had at 10% – and I did both of those. The cost appears to have been Gamma coming out at 1.65 in Custom mode and 1.85 in Cinema mode.

Does this sound possible/plausible?

Something else I noticed while looking through the service manual… it has you set Green Drives to C0 (C_Zero) (hex) and do all the adjustments with Red and Blue where it describes setting the setting factory color temps. Green Cuts also have a specific setting with all adjustments performed on Red & Blue Cuts. I did change the Green Drive settings a fair bit and Green Cut was adjusted a little to get the ideal gray scale tracking. Any possibility setting the Drives and Cuts back to the numbers specified in the Service Manual would put Gamma back to something more reasonable? I doubt I’ll be able to get the gray scale nearly as accurate without being able to tweak Green though… Red was “weak” compared to the other colors at high luminance (even though I was only getting 26 fL from the 100% white window) so I was reducing Blue and Green Gains a fair bit to get them in line with Red.