CurtPalme.com Home Theater Forum

[David_Web]

I tested my newly acquired Marquee 7500 (same as 8110 i think) and noticed a ticking noise.
It pinpointed to the location of the VDM and also changed in strength when increasing the height.
I guess the tick is from the return pulse. It was only internal pattern.

I have yet to take it out for closer inspection. The squeeze mod looks like it needs resolder so I might as well walk through the entire board.

Any reason for this behavior? And how would I correct it. Unless it's a bad solder point.


Also which way is the air suppose to flow?
The LVPS was modded with papst fans and they was sucking the air out from the PS.
Also the belly fans seems to be blowing downwards (with the PJ on the floor)

My M8000 seems to be the other way so that's why I was wondering.

[Nashou66]

Not sure about the ticking from the VDM, weird. it cold be as you say a bad solder joint and the ticking is a small arc maybe?

The LVPS fans should be pulling air through the front of the PJ and the HVPS across the LVPS out the left side if your facing the Projector.

The belly fans should be pushing air up through the FCM and HDM and also through the plastic tube housings to the neck boards , and some air gets routed through the sides of the PJ to the back to cool the rear heat sink. Its a closed system and functions best when the PJ is all sealed up(all covers on).

Athanasios

[David_Web]

The squeeze mod was the most horrible I have ever seen. I didn't need a soldering iron for the resistors to loose. The original resistors was snipped off (without desoldering) and the new resistors was sort of stuck ontop of the leftovers with no extra solder in sight.
It was not the problem though.
I went over both VDM and CONV with a magnifying glass and did not find anything worth resoldering. Everything looked perfect.
I am not 100% sure that the sound is from there, could be blue VNB or somewhere close, I doubt it though. Ill see if I can use some tubing as a stethoscope to locate the source.
Maybe a cap or something.

That's what I thought. The fans must have been installed the wrong way for some reason. Ill fix it.
Maybe the past past owner had it roof mounted and ducted the heat away from the big hole in the bottom which is as wide as the thee fans.
How bad would it be to leave the belly fans the way they are? they seems to have run fine like that for a few hundred hours.

The LVPS was some sort of Tim Martin knockoff with foam but with the fans tied in place with audio cables. Have to fix that and turn them the right way to give the HVPS proper colling.

[Nashou66]

The belly fans should be reversed to the correct direction blowing through the FCM and HDM and tubes, this is the only way the VNB,s get cooled and the rear heat sink(CVA,VDM,SWA). The design of the Marquee cooling system some say is the best design of all PJ's. One thing you can do to improve flow and lower noise a little is to cut the cage of the LVPS to reduce turbulance. Also add some Open Cell accoustic foam in the power supply cavity between the two power suplies. Make sure the front venst are not blocked.

Athanasios

[David_Web]

After some stethoscopeing the sound seems to be coming from the output transistor for the green tube. I can't see any noise or artifact in the image so it's doing it's job properly. I guess I have to reflow all the connections and see if it works. It could also be some dirt making a connection to the sink or similar.
If not I guess I have to replace the transistor.

[Nashou66]

The one's on the VNB? They are directly screwed into the heat sink correct? This is why the flow for the fans has to be set the original way, that transistor may have been damaged from lack of proper cooling.

Athanasios

[David_Web]

No on the VDM.
I could hear the ticking stronger from there than the rest of the transistors for red and blue.
Neck boards look fine from what I can see. No noise or snow what I can see.

I might as well get some soldering going and see I it sort itself out before bedtime.

[1031]

[David_Web]

Thanks.
I guess Ill leave it for now then.
Snapping those clamps on and off makes my hair crawl.
Maybe the sound disappears when running 1080i@96

The scanning seems rock solid as the tube appears to have scan line wear as I can see interference when changing size.

A quick question. Should I keep all the electronics on the tubes when I transfer the tubes from my 8000 to the 7500?
Or should I replace the 8000 yokes etc with the one from the 7500?

[1031]

[David_Web]

Ill have to compare the yokes and magnets to see if they are different. Deflection yoke I will leave on the tube regardless. magnetics, convergence and focus I think I could change it I need too.
I plan to use everything from the 7500 including tube casing. Just transfer the tubes from the 8000. At least G and B.

I do have stig yokes type: 9251.51 laying around.
And a board but no amp that will fit the 7500.
But I guess they won't do any use without that amp.

[1031]

[Nashou66]