CurtPalme.com Home Theater Forum

[Perry]

A few months ago, I purchased a Marquee 8500 for parts.

The unit was described as not turning on and having the classic H-Fail light come on on the CLM, so I knew that there was a 90% chance that the HDM had failed...and low and behold, sticking in a working HDM made the unit work! ATM I have 4 dead HDMs, which I will soon start replacing the most likely faulty FET on!

I noticed right away that the wiring was really messed in the unit, specifically the wires connecting the "blue" tube to the HDM were far too short (about the length of the red tube). On top of that, there were tubes connected to the wrong spots on the focus and horizontal boards.

Anyways, once the projector started, there was a distinct green halo (or light bias...for lack of a better description) in the shape of the raster on the green tube. I took the contrast down to 0 which removed the halo. Bringing the contrast up to 5% and the brightness to about 20% results in the halo again. Meanwhile, the actual red tube needs about 25%-30% to get any visible picture and the "blue" tube never gets any emission.

The only way that I found out that the "blue" tube was actually red was by displaying a full white test pattern, muting the green and red tubes, and driving the "blue" tube at 100% contrast & 100% brightness. At that point, a barely visible red halo comes up on the tube; trying to read the dialogue boxes from the projector are near impossible.

I switched the neck board, CLM, and vid input boards with a known working boards just to be sure that it wasn't any of those but there was no change in any of the conditions described above. I switched the HV leads around, and cleaned the corroded leads leading into the splitter, but to no avail. It looks like "blue" tube that is actually red, is dead.

My question is then, by putting a red tube in place of the blue tube, or having a dead tube cause the (HV) characteristics of the projector to drive the green tube harder than the other tubes? I would like to put a blue tube in to complete the PJ, but I don't want to kill it! Any advice is appreciated!



P.S. all the tubes in this PJ have no wear. They would all rate 10/10 on the tube rating chart! What a steal for $80! Shipping was more, but still less than the cost of a brand new tube .

[Nashou66]

Id get into the service menu and do a initialization of the set then go into the RGB menu and adjust all G2's

Athanasios

[Perry]

I did a complete initialization, but it seems that data is in NVRAM or something like it. The problem with setting the G2's is that it is set on the colour you are adjusting...not on the green tube or something. Is there a way I can safely adjust the G2 or brightness? I suppose with the "blue" tube, I can just bump it up without anything really to loose...I just have to know the menu format going into it.

[Nashou66]

Read this,

http://www.etechvideo.com/techtip1.htm

Athanasios

[Perry]

Thanks!

[draganm]

you have a dead tube from P14 over-voltage, check your G2 voltage at connector P14. Other 2 tubes are still at risk.
This is typical of what I've seen lately with surplus machines. The recycler gets a number of de-commissioned machines and try's "fixing it" by swapping parts between the different machines to try and get one working unit. So you get 2 red tubes, or plugs switched around , or worse.
For what you paid for it doesn't matter really though, just a working HVPS is worth more.

[Perry]

The filament voltage was around 7-7.5 volts as I recall, when I first got the unit. Therefore, it wouldn't surprise me that this could have been the culprit. Like you said though, I got a good HVPS, good modules, and hopefully a good green tube because now I have 4 red tubes, 1 blue tube, and 2 green tubes to work with! Maybe I'll just use the machine as a test jig for modules after doing the P14 mod...i.e. the HDM!

[draganm]