CurtPalme.com Home Theater Forum

[picree]

See attached photo. I'm feeding the proj an all black pattern. I've turned the contrast and the brightness all the way down. I thought I had a G2 problem on green but I couldn't adjust this out. This is a bad photo but it goes off the edges of the tube on both sides. It's been fine until now. It has all kinds of noise and it has those diagonal lines like the VPH06 chip on the output amp is going bad. . I tried:

-Swapping the RGB Output amp.
-Swapping the neck card.
-Swapping out the G2 board.
-Swapping the HV lead out of the HV splitter.
-I tried with and without an input signal.
-I tried adjusting the G2's on the G2 board.

Nothing would fix this. Blanking would not affect the image so it's something with the raster and not the active image area. I noticed this because I adjusted the brightness all the way down and my screen was still gray. The funny thing is it still throws a watchable picture (well...for video games). The beam is really unsteady on the green tube. Red and blue look fine. Could it be the focus coil? What's left to check but something with the tube?

OK-any takers?

[Tom.W]

Could be a heater to cathode short in the Green CRT.

Read page two of this PDF...

http://repairfaq.cis.upenn.edu/sam/reppic/sencrt.pdf

[Curt Palme]

I've got a 7000 to zap it if you want to send it in.

[Curt Palme]

I've got a 7000 to zap it if you want to send it in.

[jkruger]

Use a Sencore to zap it or try tapping lightly on the neck near the coils to knock it loose.

[picree]

All good information. Thanks for all the advice and the info about the 7000 Curt. I was afraid the next step was to swap the tube out. I'll try to shake/tap it loose. I've also got two spare green tubes. It may be time to send one off to VDC. They are still in business right?

[HaydnG90]

Had the same problem on a blue tube on my 808S. Gentle tapping on the neck dislodged the contaminant causing the short and all was well.

[Tom.W]

If indeed it is a heater to cathode short tapping the tube neck might be the only alternative as you can easily burn out the filament before the short is cleared with the CR7000. Get out the ohmmeter to verify one way or the other.

[secstate]

I had a similar problem with a new blue MEC P16. I couldn't get enough force to tap with the but in projector but removing the tube and firmly clapping my hands with the tube neck in between (to balance the force and not snap the neck) removed the problem. I had to do it pretty firmly to finally dislodge whatever was causing the short.

[jkruger]

Looks like Barco makes a tool just for this.
http://cgi.ebay.com/BARCO-BALL-PEEN-HAMMER-04416_W0QQitemZ220398457819QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3350c593db&_trksid=p3286.m20.l1116


This must be the Runco model prior to relabeling:
http://cgi.ebay.com/Barco-04-002-Ball-Peen-Hammer-2-oz_W0QQitemZ350246297502QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item518c4e5f9e&_trksid=p3286.m20.l1116


Here's the Gary Murrell model too:
http://cgi.ebay.com/NEW-Barco-08-294-26OZ-Half-Hatchet-Hammer-W-Nail-Slot_W0QQitemZ310170950274QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item4837a11a82&_trksid=p3286.c0.m14

[perisoft]

[picree]

[picree]

Just to close the loop on this...I removed the tube three different times and tried banging on it in different ways as hard as I thought I could without breaking the neck off. I couldn't get the shorted piece to knock loose. So, in the end I replaced it with another green tube (crappy one I had) and the problem was solved. It was a shorted tube.

[tse]

Did you measure a short with an ohmmeter? If it is not a short it might be secondary emmisions. A zap with the Sencore can often clean that up.

Scott