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Discussion Starter · #1 ·
Hi!


It's been a long long time since I've posted here. I've been so busy I just haven't had a chance to contribute much lately, so I hope my request for assistance doesn't come off as being too rude...



Time was, when I first turn on my Marquee 8501LC, the focus has to be set to about 28. Anything below that doesn't seem to alter the picture at all (not even defocus it.... what's up with that?) . As the PJ warmed up, the focus had to be gradually turned up.


Lately the focus setting requirement was rising like crazy -- last night at the end of my movie I had it set to 100 for it to be in focus. I knew something was seriously wrong.


Then, like an idiot, I forgot to turn off the PJ. With a blue screen showing no less. This morning it wasn't even in focus at 100 any more.


I turned it off and after a few hours turned it back on. Now it wouldn't focus, but wanted to be below 0. 15 seconds later it was focused at 25 and then suddenly jumped to 50. I also noticed there was a faintly audible click that accompanied the jump to 50. Could this be just a bad contact issue?


Other symptoms include width jumping. For a long time now the image would suddenly go black for a few frames or sometimes the image would suddenly get wider or narrower by a few inches. When this happened the focus would also change a little. Sometimes the focus would jump too.


I'm going to try cleaning the focus board contacts any any socket mounted components with DeoxIT, but outside of that, does anyone with experience have an opinion about the best place to start troubleshooting this? Focus board? I2C resistors? Op amps? Power supply?


I have all the tools and expertise required to fix it myself, just not the time to learn the entire inner workings of the machine. Really I'm just looking for someone with experience to point me in the right direction so I only have to read one or two schematics instead of all of them.


Thanks for input...


Chiem
 

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Clean the HDM contacts, main and daughter boards. I've seen your problem ONCE in a set, and it was recently. IT sounds like your HV is drifting. Mine had a bad HVPS that was drifting, causing fluctuating focus. I tried three focus boards before I realized that drifting HV can also cause drifting focus.
 

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Hey, Chiem... welcome back. Have you been off to some (even more) exotic locale playing mad scientist?
 

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Actually Scott, that's what threw me, mine didn't! (change in size)


It was a very late model (2000) Ultra and must have been drifting by only a few Kv overnight. I was test running the set and it was out of focus the next morning. Focus at 100 to get the menus to be readable but soft. I haven't gotten into it yet, it should be something in the lv section of the HV supply, but I went onto other things. I'd think the sealed silicone section would be OK.
 

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Discussion Starter · #7 ·
Wow, thanks for the quick response guys! I can't believe you actually remember some of those posts I wrote...



It might take me a few weeks but I'll let you all know how it goes. Thanks again.
 
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