CurtPalme.com Home Theater Forum

[digitalayon]

Are most Marquee neckboards interchangeable? Say a 8000 Vs. a 9500?

[Tim in Phoenix]

Yes

There is more to it than that. Early VNBs had many problems from smearing to complete failure; you will see small parts tacked on all over the place for 25 or 30 revisions. Many failures were arc related, and the problems were well sorted by 1995 when the 8500 and 9500 rolled out. Also, the nine inch VNBs were keyed so not to fit on eight inch tubes, as the beam limit was set higher. You would need to shave some plastic off the tube end cap to make those work. The MRF white button transistors were discontinued maybe six years ago, and VDC completely redesigned the VNB when their supply ran out. For replacing earlier VNBs, these are best used in sets of three.


Some of you know I was the technician for Electrohome CRTs in the Detroit area for many years, with clients like Ford, GM, Chrysler, EDS, U of M, Lear, and dozens of others.

When the Marquees first rolled out in late 1992, Ehome invited near 200 of its' dealer personnel to Toronto for the big news. The Marquee was their first CRT with tubes bigger than seven inches as well as their first magnetic-focussed chassis. The M8000 was to replace the ECP series, with the M9000 as their first LC offering. The M8000 sold nicely after the intro, but we were seeing a lot of soft failures in the neckboards, with the symptom usually streaking, which was determined to be failures in certain small transistors on the neckboards. Tube arcs was believed to be causing these failures.

My life became hell as I had to change out two or three sets of neckboards every day for several weeks, and the replacement boards were failing too. Ehome stopped shipping new projectors to us while they sorted out the problems, which was not good news either.

To study these failures, the Ehome engineers wanted arcs on demand, so they contacted the physics department of a university nearby. Two guys from the university paid a visit to the Ehome plant, discussed what was needed, and they brought a powerful laser on their return visit. By firing the laser at certain points on the electron gun, they would vaporize a small amount of metal and the tube would arc most every time. They could measure the arcs hitting devices on the neckboard, and the appropriate diodes and caps were added for a more robust design.

I am not sure what became of the laser-drilled test machine.

[digitalayon]

OK....So if I have an older one, can it be "updated"?

[Curt Palme]

you want either the 50-2038 or 50-2039. No, older boards like the 50-2013 and 50-2000 cannot be updated. I've got stock if you need one or more.

[Curt Palme]

you want either the 50-2038 or 50-2039. No, older boards like the 50-2013 and 50-2000 cannot be updated. I've got stock if you need one or more.

[digitalayon]

I will check when I get back later on. Some dude dropped off a 8011 at me house the other day. Wants it fixed after he blew it up on a power spike.