CurtPalme.com Home Theater Forum

[Elaine Benes]

Basically I got out of the Marquee as my "main" projector because pretty much every single Marquee I've had, has had a bad HVPS. Intermittent problems which manifest themselves as fluctuating brightness either in one or all tubes, and sometimes shrinking picture size or winking out and coming back...very frustrating. They don't do it all the time, and one I had, I used it for years like this, and *usually* it worked perfectly, but there is no doubt the HVPS was "bad".

So can these symptoms of a bad HVPS be repaired in some way at all ??

I've just been given an 8500LC with new tubes, and I'd like to use it, but the damn crap HVPS is doing what these crap HVPS's always seem to do, is there any repair ?

I refuse to put big money into a projector that isn't worth the cost of the parts, so if there's no fix for the HVPS, the projector is getting scrapped. I'd much prefer NOT to scrap it, but I've seen the asking prices for HVPS's here, and they're way too high to justify NOT scrapping this, especially if they'll just fail like the one I've already got is failing...

So, is there a fix for the crappy Marquee HVPS ?

Thanks.

[the_maniac]

so do you think the picture loss for about 1 second or somewhat is caused by a bad hvps ?

[Elaine Benes]

[tse]

Things other than the HVPS can cause the shut-down/restart problem. The HDM can cause that and the vertical deflection, though not as common. There are literally thousands of Marquees in the world that do not have HV problems.

Scott

[Elaine Benes]

[Nashou66]

Ok, that can be a bad VNB. Pull the umbilical cord from one VNB at a time. Turn on the PJ and ramp contrast. If it doesnt happen with the VNB that is removed then you that is the bad VNB. If it still happens then I would try a Vim next. Then a different HDM etc till your sure it is not any other board.

A good cleaning of the CLM chips is also suggested.

Athanasios

[Elaine Benes]

[Elaine Benes]

Just switched the red HDM connector with the green, the fluctuating brightness stopped(co-incidence ?) but the picture still winked out three times while I touched up convergence(using internal pattern, so no video even being displayed...).

[Curt Palme]

[Curt Palme]

[Nashou66]

I agree with Curt, of the 6 marquee's i have not had one that has a bad HVPS and One set has over 50k on the chassis (M8000) .

Unless you have another PS to test in it , it would be hard to diagnose at this point.

Athanasios

[Elaine Benes]

Then scrap she be...thanks.

[zGman]

You know it seems to me that I recall also seeing similar symptoms
with "leaky" anode leads on a marquee - also have seen shutdowns
from a tube with a G2 "short" & that problem got worse as contrast
was increased. Also on a barco fluctuations ended up being the HV
splitter. Good luck getting it going, very sad to toss a nice set....
G

[Nashou66]

I agree, disconnect each HV lead one at a time.

Athanasios

[Curt Palme]

It is indeed puzzling why once in a blue moon a Marquee 'eats' HVPS. The problem is, they usually last 3-4 months, so it's not a dead short anywhere. I agree, a leaky HV lead that puts a greater load on the HVPS over time could be it, as could a leaky HV splitter, but you'd think you'd smell the corona coming from said lead.

You might try that first, change the splitter and all three HV leads going to the tubes, and wrap the output of the HVPS with electrical tape and see if the problem goes away.

[Curt Palme]

It is indeed puzzling why once in a blue moon a Marquee 'eats' HVPS. The problem is, they usually last 3-4 months, so it's not a dead short anywhere. I agree, a leaky HV lead that puts a greater load on the HVPS over time could be it, as could a leaky HV splitter, but you'd think you'd smell the corona coming from said lead.

You might try that first, change the splitter and all three HV leads going to the tubes, and wrap the output of the HVPS with electrical tape and see if the problem goes away.

[Sparky015]

Do you see any error lights when the HV powers down? It's tripping the safety circuit, so maybe it's lighting an error code that may give you an indication. I have a spare HVPS and VIM if you'd like to try them.

How do the VNBs look? Is the G2 wire darkened from excessive current, do the two large resistors have burn marks at the solder joints? Just wondering if they are tired and the two electrolytics need changed, and by swapping VNBs around, your just moving bad boards around.

[Elaine Benes]

I changed the splitter, which didn't affect the issue one way or the other....

While it certainly *could* be a bad HV lead, the tubes are virtually new(with installation in the LC chambers, and HV lead installation done by VDC), and while I know that CERTAINLY doesn't preclude a bad HV lead, I'd think its less likely...

Would it be worthwhile to add a coating of silicone around the anode connector at the tube bell ?

I don't have any "new" HV leads available to swap in to try ...

The H-Fail light has lit briefly when the image has winked out, but no error lights show when the fluctuation in brightness occurs. I just ran it all morning, with no indications of the issue till the last hour or so when fluctuations in brightness started to occur...When I initially turned it on, it winked out three times while touching up convergence, so overall picture brightness was very low when it winked out and came back...

I'll look at the VNB's, but from memory, I think they look very good. The big cap's in the corners were replaced as an improvement "mod" by the previous owner, the work was done by a fairly accomplished solderer, using good quality caps.

[dvh99]

if the picture goes away with convergence touching up then maybe the cva transistors are running too hot.
solder the joints from the transistors on them and clean the heatsink and apply new heatsink compound.
do the same on the hdm (soldering the transistor joints) replace c50 there too.
could be a bad solderjoint.

[Curt Palme]

I'm guessing the HVPS is fine. It can't trigger any error LEDs, and when they die, they almost always go dead. I have had one that had an arc path between one G2 PC board trace and another, and that caused no red (or whatever color was shorted out, I can't remember). But that was one out of 100s I've seen through here in sets and in units I've parted out. My guess is you have a bad neckboard or bad HDM.

[Curt Palme]

I'm guessing the HVPS is fine. It can't trigger any error LEDs, and when they die, they almost always go dead. I have had one that had an arc path between one G2 PC board trace and another, and that caused no red (or whatever color was shorted out, I can't remember). But that was one out of 100s I've seen through here in sets and in units I've parted out. My guess is you have a bad neckboard or bad HDM.

[Sparky015]

yeah, I would say HDM. Sometimes those error lights can be misleading, but I would bet there is a bad solder joint or a cap on the hairy edge that is causing this issue. I agree with CUrt, your HVPS is probably just fine. I would also take a look at what Dennis pointed out.

[tse]

If the H Fail LED comes on that shuts down the HV. Safety feature to protect the tubes. High h size setting with alot of keystone can cause momentary shut-down. The fluctuating brightnes is interesting. Might or might not have something to do with the HV output.

Scott