CurtPalme.com Home Theater Forum

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

I've got a relatively minor but very annoying problem with my 8500. There is a "ripple" in the raster that produces darker/lighter stripes across the screen, making it look almost like big fat scanlines. This happens with all the inputs I've tried, including none. It appears on all three colors, and it's identical on all 3 -- i.e. I see the ripples clearly on a full white screen with no color variations. That says to me that the 3 colors are all getting the same ripple in some input, otherwise they'd ripple at different times/speeds and you'd see colors on a white screen. It's present immediately after a full reset, so it's not like the common "banding" problem.

I can't quite tell if it's caused by a variation in thickness of the scanlines, or a variation in spacing. It's very difficult to get a clear picture of it, especially close-up, but I've attached a few to give you an idea what it looks like.

With Dragan's help I've tried to isolate it by swapping out components. So far I've swapped out:
* VDM
* VIM (swapped in an old 8000 VIM, looked awful, but still had the ripple)
* DPB (the deflection daughterboard on the CLM)
* Neckboard (put an 8000 VNB on the green but it still had the ripple)
* LVPS

I tried unplugging the focus module. The ripple was harder to see on a blurry raster but it was still there. I removed the color correction module, no change.

I don't think it can be the CLM, since I assume that's all digital. As I understand it, the CLM sends commands to the DPB, which converts them into waveforms that the VDM amplifies -- correct?

I can't think of too many other things to try. About the only likely suspect left is the HVPS, but Dragan doesn't have a working spare to try. I may try dropping my HVPS into one of his machines, but he's an hour away so I might not get there right away.

Help!! Any ideas?
Thanks,
Gary

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Hello

Try unplugging convergence and stig yokes for one color and see if any difference.

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

OK, convergence would be the orange/purple/black wire going to the center board on the heatsink, and stig would be the blue/purple/white wire going to the board on the red-CRT side -- right?

**Curt Palme** · Posted: Thu Jun 28, 2007 10:45 pm Post subject:

Yes. It can also be a ground loop or something in the signal. Disconnect the input ( I know you said you tried it with no input, but did you actually disconnect the BNC connectors so that the set is sitting there with nothing but the power cord connected?

Then yes, disconnect the conv. and stig leads.

If not, I'd try the HDM or LVPS and HVPS as suspects.

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Aha!! Now we're gettin' somewhere!

I disconnected all the input BNCs and powered it up -- ripple was still there.

Powered off, pulled the red stig/conv, and powered up -- and the ripple is **GONE**!!

So: what does this tell us? What do I do now?

Thanks guys!!!

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

The CLM? That's one of the few things I haven't swapped out. Dragan and I popped all the chips on it and cleaned them with De-Oxit, but we didn't try a different one in my set. Guess that's next...

CZ Eddie · Joined: 23 Mar 2006 Posts: 1601 Location: Austin, TX

Gary, did you ever figure out the 1/3 image square box thing?

Good going on tracking down the ripple, btw!

mp20748 · Posted: Fri Jun 29, 2007 12:29 am Post subject:

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Yes Mike, I remember you suggested the CLM as a possibility. I've just had so many possibilities it's taken a while to try them all. Smile

If it's caused by the CLM, do you think it would be worthwhile doing some maintenance / cap upgrading before I get myself a different CLM? I'm not having any focus problems that I've noticed.

Eddie, I realized I had some brightness issues with my DVD player. When I increased the DVD brightness and lowered the projector brightness, the square disappeared.

mp20748 · Posted: Fri Jun 29, 2007 2:21 am Post subject:

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

How can I turn down an offer like that!? Thanks Mike!!

jcmccorm · Joined: 15 Jan 2008 Posts: 21

Any update on this Gary? I've got an 8500 that I just set up for my brother-in-law that does this. I hadn't tried pulling the convergence connection yet but it looks like the same thing. Did the CLM update/upgrade fix it?

Cary

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

No, Mike's updates didn't help, unfortunately. Curt sent me a different CLM and that one solved it. I think Curt said my CLM didn't show the ripple in his test projector??

I still haven't seen it in action -- I've had a G70 in the HT for a few months but I plan to put the 8500 back in service fairly soon -- but the ripple was clearly visible on the tube face before, and now it's not. So I'm 99.99% sure it's finally fixed, yay!!

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY