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Marquee technical experts, explain this challenging problem!

263 Views 3 Replies 2 Participants Last post by cmjohnson, Mar 2, 2005

cmjohnson

Discussion Starter · Mar 1, 2005

Here's a real challenge for you. Post what you think the problem is.

Projector: Marquee 8000.

Symptom:

Projector in CONVERGENCE mode.

RED raster: All non-center zones move and converge normally.

BLUE raster: All non-center zones move and converge normally.

Attempts to move the RED raster via the CENTER zone move

the BLUE raster INSTEAD. This is only visible after switching to the

BLUE convergence screen.

Attempts to move the BLUE raster via the CENTER zone move

the RED raster INSTEAD. This is only visible after switching to the

RED convergence screen.

The yoke harnesses have been triple checked, removed from their

board sockets,, and reinstalled in their board locations with EXTREME care,

working with only ONE tube and connector at a time. Wherever the listed

color is present on the silk screening of the boards, the connector has

been matched to that color with great care.

The problem continues exactly as described.

Post your best guess.

Problem 2: Crosstalk between channels. Turning up the G2 settings

on any tube with the other tubes shut off results in the shut off tubes

showing a raster, too. This occurs at higher G2 levels than you would

normally use, but I would expec the three channels to be completely

independent. Apparently there is some crosstalk. What's the diagnosis

and cure?

CJ

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analoggman

· #2 · Mar 1, 2005

Problem one

Switch the red and blue horizontal plugs

Problem 2... what do you mean crosstalk?

Check integrity of the video cables (from input board to neckboard)

I have seen where the wires get kinked or shorted when the you put the convergence hinge up.

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cmjohnson

Discussion Starter · #3 · Mar 2, 2005

Diagnosis on problem 1: Will be checked shortly. Probably correct.

Reason: Center convergence zone does NOT work on the convergence circuit,

but instead works on the horizontal deflection circuits.

Problem 2: By crosstalk I mean, hit COLOR 2 on the remote, shutting down

red and blue guns. Now start cranking up the brightness and contrast on

the green gun and look in the lenses at red and blue. They start to show

an image as well. It gets bright enough to visibly change the color balance

on the screen.

CJ

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cmjohnson

Discussion Starter · #4 · Mar 2, 2005

Diagnosis confirmed. Red and blue yoke plugs swapped at the HDM.

As the HDM in this case is the type where the color code is not printed

on the board, it's an easy mistake to make.

You passed.

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