CurtPalme.com Home Theater Forum

[digitalayon]

This is a 50-2013-05P neck board and it looks like it has been modded with caps and inductors. Was this thing modded or is this stock, or is it a factory improvement? It does not look factory to me. Or just really old board. Unless it is one that was modded for brightness issues. Pulled it from an 8011.

[gjaky]

It's a stock neck board, actually from a late model M8000/9000. You can tell if it is a vintage one from the "metal can" transistors there (1st pic next to the RCA), which was replaced by plastic ones later those are faster/better. I think the great modders like Mike always saying that stay away from these boards, they are only good for parts donor.
On the other hand I did a direct comparison between these old and the newer boards, and the difference was subtle (for me) at standard 1080p resolution.

[Curt Palme]

It's the Canadian way. When you can't design it right the first time, just add more parts.







I believe the Chinese have adopted this policy in recent years.

[Curt Palme]

It's the Canadian way. When you can't design it right the first time, just add more parts.







I believe the Chinese have adopted this policy in recent years.

[Tim in Phoenix]

Guys

The small parts added were to deal with tube arcs killing the neckboards.

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]