CurtPalme.com Home Theater Forum

[JustGreg]

A neighbor across the street, who just moved into the neighborhood, has a 1998 8500 non LC or Ultra. After it's warm he tells me the image blinks black very fast one time, and then the focus is gone. He can go into Focus and ramp it up (or down...depends on which focuses it) and fix it but he says that when he achieves what he thinks is good focus, the on screen focus box and numbers are yellowish. To get them white, he has to take the focus either up or down from the optimal setting. He says that a little while later, perhaps an hour, the pic blips again and he loses focus again. This time he has to change the focus in the opposite direction of the last burp. rinse and repeat.

He knows his way around his 8500 about as well as I do mine but between the two of us all I could come up with is a guess that the F board is failing. Without access to literature outlining the responsibilities of the boards, that's the best I could do. I pulled the F board and cleaned it with Deoxyt and inspected it but there's nothing visible that would account for it. Is Focus maintained on the F board or on the VIM? Could it be the battery getting ready to go? (I thought all the memory locations were wiped when the battery was kaput but...).

I turned him on to the forum. We'll see if he shows up as a new member. He's got money so I'm more than a bit curious why he doesn't have a 9500. I'm guessing it's because he's had his 8500 since getting it new and may just be comfortable with it for his usage level.
I lent him my spare F board last night to see if it's still happening. I couldn't lend him my VIM as it's kaput at the moment...I'm awaiting a replacement. I'll also be checking his heater voltage tonight so we'll see if the F board fixed the problem. It's a nice feeling to be able to apply what I've learned from you all to help someone else!

[Nashou66]

First ask how long its been since he has cleand all the contacts and the chips on the CLM?
If thats not it Have him clean the contacts on all connectors including all daughter boards,CLM,HDM,and even the HVPS Sub Board.
Then i would try swaping VNB's with say the red and blue since you said the focus box numbers are yellowish which would to me mean low blue emission and a possible band Blue VNB.

Once he tries all that we can move forward if its a board level failer that you might have to swap boards out with him to find it.

PS, Its So cool you have a neighbor who is into CRT FP !!!!

Athanasios

[Curt Palme]

Couple of things:

1) Could be an HV arc somewhere that is messing with some setting somewhere. Some little arc, even in a screen (G2) lead could do that.

2) Arcing internally in the HV could shift the HV by a couple of Kv, which would affect focus.

3) Intermittent CLM that affects the focus settings that are sent to the focus board.

But I'm with you, I'd change the F board first.

And yes, what are the chances that a CRTer moves into the neighbourhood close to another CRTer, and knows his stuff? Welcome brother!

[Curt Palme]

Couple of things:

1) Could be an HV arc somewhere that is messing with some setting somewhere. Some little arc, even in a screen (G2) lead could do that.

2) Arcing internally in the HV could shift the HV by a couple of Kv, which would affect focus.

3) Intermittent CLM that affects the focus settings that are sent to the focus board.

But I'm with you, I'd change the F board first.

And yes, what are the chances that a CRTer moves into the neighbourhood close to another CRTer, and knows his stuff? Welcome brother!

[JustGreg]

Thanks for the replies. Holy hell...things were busy in the last 12 hours...I had to dig to find this.

I mentioned a good cleaning and especially reseating after moving it. Damn, the guy already has it ceiling mounted and he's only lived there for a couple months! Makes things a lot more difficult. I saw it do the 'thing' last night and I didn't hear a snap crackle or pop. Just a quick black screen...fast as a blink...and then out of focus it went. We pulled the CLM and VIM and didn't pull any chips (I couldn't find my puller ) so we just crunched all the IC's back into the sockets. We cleaned dust off the HV leads and made sure they were secure, checked all harnesses and connectors, and pulled the HVPS and LVPS and reseated them. I wanted to open them up (LEMME AT IT!!!) but it was getting late. I left my F board over there for him to try if it did it later.

Yeah...lucky to have a CRT-er for now....he's thinking of going, *ULP* to a one eyed monster. He asked my opinion of di$itals and all I could do was stare at him. I know just enough to be dangerous with my 8500, never mind give any advice about digitals. I asked him to check out Curts offerings for high end pj's before he did anything rash. We'll see. I think he wants a Ron Popiel projector....Set it and Forget It.

Thanks again. I'll let you know if the F board and the rest of what we did worked out.

[antorsae]

Ceiling mounted you say?

That's almost positively the problem. Remove the FGM and HDM shield covers, remove the foam and put a good number of layers of adhesive tape so that the FGM and HDM are securely pressed against the motherboard. The stock foam tends to lose stiffness so the FGM and HDM may "fall" a bit.

I suffered from exactly this problem and aside from cleaning all contacts, etc. I also made sure the FGM and HDM were strongly secured to the motherboard.