CurtPalme.com Home Theater Forum

[CRT_Ben]

(edited to include recent troubleshooting info...and cut out the part where I'm crying like a baby )

Hey guys,

My PJ has been running like a top recently, so before my superbowl party yesterday I decided to tweak the astig and flare as it was looking a little off. I took the top cover off and moved the HV splitter/tube covers to tweak the astig/flare. When I started it up the blue tube problem presented itself (pic below). Other symptoms are the tube cutting in and out randomly, seems to be "off" more than "on" (this is looking on screen). However, when looking in the lens, those weird retrace lines are always there, and the pic is just really, really dim with occasional flashes of normal brightness.

I have reseated the VIM, focus board, HDM, neck board, CLM, HV leads, HVPS, LVPS. The problem seems to be independent of G2/drive controls.

I swapped the VIM and G2 leads from the blue to the green and the problem followed the wires (green got wacky, blue was fine). I didn't have time to swap the VIM/G2 leads independently to see which one was the problem.

Is the G2 signal delivered right from the HVPS? If so, is the G2 section potted?

Thanks!!
Ben

[Zebu Fellenz]

Have you tried swapping the neckboard.

Try reattaching the HV lead.

[CRT_Ben]

[Zebu Fellenz]

Try swapping the G2 and VIM leads indepentent of each other, this will narrow down the problem.

Also check the VIM lead connection on the VIM, I had those come loose on my 8000 and it caused all sorts of problems, however I never had anything that looked like that. My guess is it's G2 related.

Erik

[CRT_Ben]

[CRT_Ben]

Ok, I've edited the first post to add new information and much-needed coherency.

[CRT_Ben]

OK - I bought some contact stabilant tonight, and went through cleaning a bunch of contacts, pressing down on socketed chips, etc.

The set is responding to the remote again, which is good news - so now we're back to the original problem of the faulty G2 signal. I put the VIM wires back to their respective tubes but left the Green and Blue G2 leads swapped. The problem is still on the Green tube, so this is solely a problem with the G2 signal. Does this indicate a bad HVPS? Can the G2 section be fixed?

Thanks in advance,
Ben

[Nashou66]

Take out the hvps and check the 560kohm reisitors see if they are all close to the same value for each G2(color). Also look and smell around to see if anything burned up on the HVPS. There are pics of modded HVPS on the Marquee group purchase thread to see what i'm talking about.

Athanasios

[CRT_Ben]

[draganm]

[CRT_Ben]

Ok, I didn't have time to find the multimeter tonight to measure the resistors, but I did open up the HVPS and snap a few pics.

It's kind of dusty...


and there's this white crap all over the circuit board near the potted section (it's in the lower left of the first pic, too) - not to mention a spider web!


I'm going to give this a good cleaning and bust out the DMM tomorrow. I'm not sure if the dust and white crap are causing any problems but I'd sure rather have a clean circuit board!

[1031]

Those tree transistors (2sc4636) near 560k resistors are for g-2 adjusment, so look solderpoints closely and measure also those transistors.

That white "stuff" is normal..nothing to worry.

[CRT_Ben]

[1031]

If i got time later at this day, i take measurements for you so you can compair those values..This is not promise, but i trye

[1031]

http://www.allaboutcircuits.com/vol_3/chpt_4/3.html

Ok Use diode range on your multimeter, red lead to pin 1 black to pin 2 and then to pin 3
Pin1-pin 2 = 0.650v and pin 1-pin3= 0.679v
Those numbers doesent must be exactly same but close to 0.6-07v is ok.
other ways (black to pin 1 etc... and red and black lead between pins 2,3) should read OL

Pins are looked at front: 1,2,3 B,C,E

[CRT_Ben]

[CRT_Ben]

OK well everything seems to check out with the transistors, except there seems to be a reading between b1 and r3 - is this normal?

Here are my readings, r=red and b=black leads. In order from front (away from potted section) to back:

T1:
r1-b2=.593
r1-b3=.638
b1-r3=.925
everything else OL

T2:
r1-b2=.593
r1-b3=.640
b1-r3=.926
everything else OL

T3:
r1-b2=.592
r1-b3=.640
b1-r3=.916
everything else OL

[CRT_Ben]

Okay so go figure...after cleaning the HVPS boards and working on some other projects, I came back to the PJ and decided what the hell, I'll put the HVPS back together and fire it up. Wouldn't you know it works like a champ! Probably the only meaningful thing I did was put contact stabilant on that little HVPS daughter-board connector. I'd been wanting to do a setup from scratch so I did a reset and spent about 2-3 hours setting it up, it's been rock solid. Hopefully whatever was "broken" has been fixed, I'm not gonna look the gift horse in the mouth

Thanks for all your help guys!

Ben

[1031]

Good to hear that was only contact issue

[CRT_Ben]

Okayyy...

Well, tonight I was watching the PJ and all of the sudden the blue tube went out. No nasty noises, nothing, just disappeared. At this point I'm figuring that my magic "fix" of cleaning contacts wasn't quite enough

So I walk around the front of the PJ and I find that the raster is slightly lit, as normal, in the blue tube, but it's like it's not receiving a video signal. None of those crazy retrace lines and flickering I was seeing before. I ramp the G2 up and down and the raster responds normally. I unplugged the PJ, pulled the VIM, and swapped the green and blue leads. Fire up the PJ and lo and behold the blue and red light up, but no green! Green raster is softly, normally lit, just no video. For one last troubleshooting data point, I swapped the blue and green input BNCs to eliminate a possible source problem.

SO! I guess I have (had? still hoping the G2 problem is gone) two problems that have similar symptoms but are probably unrelated? Still I find it VERY strange that the blue G2 would act up, and suddenly after, the blue channel on the VIM would act up. And I know it's the VIM because the source checked out when I swapped the input BNCs, and the blue tube worked fine when hooked to the Green channel, so it's not the neckboard. I don't suppose that a problem with the blue tube or neckboard could cause the input signals to the tube to act up??

Thanks for all your help, guys!
Ben