CurtPalme.com Home Theater Forum

[ralpharch]

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[Rolls-Royce]

Ralph, my EXT-HD's main board has the pot nearest the VGA connector marked VR3, and it's the one Moome had me adjust to correct my problem with the component input. It worked, so VR3 being the component sync pot is verified. The one under the ribbon cable and next to the socketed IC is marked VR1. Since we know VR3 is component sync adjustment, VR1 has to be the gamma pot, as Moome says.

[ralpharch]

Thanks for confirming which pots are which - I did not recall seeing labels but I know now (and can see the vr3 labling on the photo I posted in other thread.
http://www.curtpalme.com/forum/viewtopic.php?p=137708

[Rolls-Royce]

Ralph, if they didn't get a chance to check your VR3 before it was sent back to you, checking it yourself when it arrives is simplicity itself. There are 3 pins on the bottom of the pot that go through the board. Using a digital multimeter, check the resistance between the 2 outer pins. If it's less than 5Kohms, turn the pot clockwise until it is at 5Kohms, and you're done!

[ralpharch]

Thanks for telling me how to get it set right. When I get the box back I will try it on HDMI and component and adjust as necessary.

Ralph

[Rolls-Royce]

You're welcome, Ralph. That's how my component input got screwed up. Like you, I adjusted the pot out in the open-VR3-thinking it was the gamma pot. You may be able to do the adjustment without taking the board out. There's a tiny test point right at the adjuster end of the pot. One of the pot's end pins goes through the trace that test point is on, and the other end pin goes through a large common trace-probably a ground-that has numerous small test points in it. It might be possible to make the adjustment using those test points rather than removing the board and flipping it over to get at the pins like I did. I'll check that out when I have time tomorrow and let you know.

[moome]

to prevent mis-tuning the VR3, all second batch of EXT-HD replace VR3 by one resistor.

[Rolls-Royce]

Thanks for the update, Moome.

Ralph, I'm sorry but the board has to be removed from the box to check the VR3. The test point I saw next to the VR3 adjustment screw actually goes into the same large common trace, so it'll only read 0 Ohms and not the value of the pot.

[ralpharch]

Thanks for feedback Royce

I just use the HDMI anyway so just will file a printout of this thread in the box in case I ever need component input. Maybe hook up the component one time to see if I even have a problem.

Those little screws were suckers to get out when I was trying to fix the power connection, so no sense going there if I don't have to.

Edit -

Got mine back from Moome - the power connection was fixed. Tried the component and it syncs/works fine - so I'm not going to fiddle with it (VR3). Don't know if Moome set it before returning it or my particular setup is not sensitive to whatever I did to the control.

Unit still has the lack of response to remote unless its powered off/back on; so I went back to powering it offreceiver. No sense challenging the power connector again.

[Rolls-Royce]

[Rolls-Royce]

Just a further post script to this: I changed the gamma formula that I was using in CalMAN based on the recommendation of another CalMAN user, and found that adjusting the gamma pot for more boost wasn't needed. I was able to bring it right in line with the target curve with just about 3 remote clicks down from the full "up" position on the gamma control. By changing formulas, I went from an on-off contrast ratio of ~1000:1 to 36400:1 using the same 2.3 gamma target.

[moome]

[Rolls-Royce]

Hi, Moome. I use an X-Rite I1Pro with CalMAN software. CalMAN has an advanced grayscale calibration layout that computes on-off contrast during a grayscale run. To be honest, I had to adjust my set's gamma control and then the EXT-HD's gamma control to bring the actual luminance measurements in line with the new calculated values, but that was it. I had been using the ITU/EBU Standard gamma formula in CalMAN, but had noticed some plotting anomalies for Black in the resulting Point Gamma chart. Another user suggested I switch to CalMAN's Power formula, which more closely mimics CRT response, to fix the gamma graphing at Black. Doing this then making the gamma changes gave me that huge jump in contrast ratio plus a much punchier and 3-dimensional picture. I can't say that I ever felt the picture was "washed out" before, but it sure isn't now.