CurtPalme.com Home Theater Forum

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

Ok, so I am trying to do the mechanical astig on a Runco 930. When doing the blue tube, I cannot see a dot inside the blob using the Course Dot Pattern. I tried increasing the contrast to 100%, lowering and raising the brightness 0-100%, and then defocus via the pot. I turn the pot both clock-wise, and counter clock-wise. (Defocus switch is off.) Still no dot.

When I put up the Cross Hair pattern, there is only a solid blur, vertical and horizontal; no “brighter line” in the middle of the blur.

The green and red went just fine. I can see a dot inside the blob, and when looking at the Cross Hatch pattern, I can see a solid bright line both vertical and horizontal.

The other nec 6pg xtras I have done astig on were somewhat similar, but I was always able to see a little bit of a blue dot.

Any thoughts?

Thanks.
wallace

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

Shameless bump, but I am stumped and having anxiety. Embarassed

This pj only has 1635 hours, and the blue and red tubes are a 9, green is between 7.5 and 8.0. I tried swapping boards with another 930, as well as boards from my other 3 nec 6pg xtras. No luck. Same problem.

wallace

**Curt Palme** · Posted: Sat Sep 26, 2009 4:55 am Post subject:

It was said long ago that a dot in the middle of the blob was a bad thing, that the tube had a worn cathode. I since proved the avs poster wrong ( I'd sold him the set, and be bitched on avs long ago)(, as I've seen some very low hour tubes with the dot in the blob, but some tubes have it, some don't. Just concentrate on the blob being round no matter how in focus or out of focus you are.

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

**Curt Palme** · Posted: Sat Sep 26, 2009 5:26 am Post subject:

the original post was that the cathode was worn if you saw a dot in the middle. Customer accused me of installing a crappy tube, then I saw in the NEC s/manual that NEW tubes have cores (dots) in the middle, so I posted that, and it was all good. Not sure what causes a core to be/not be there, but either way works.

Mark_A_W · Posted: Mon Sep 28, 2009 5:10 am Post subject:

Cathode is worn if you have a hole in the middle, not a dot.

Wallace, you want the blue to be a touch out of focus anyway. Just do your best, and turn the Blue Defocus switch off before you start (next to focus pots).