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G90 - Rectangle of flashing black lines.

post #1 of 19
Thread Starter 
This week I started seeing a pattern of lines flashing on the screen occasionally while watching movies.

The first few times I noticed it there were horizontal bands of them that would appear and disappear quickly.

Since then it seems to have gotten progressively worse, and now it is clear that its a whole rectangle of lines. The rectangle pattern flashes for a bit and then goes away. Sometimes only for a second or two, and sometimes for much longer.

It happens regardless of which input is used, and does not matter if there is an external signal or not. I have removed my moome card and put the projector on Input-A with no signal attached and it still shows up on the test patterns.

The lines disrupt video and the test patterns generated by the projector, but do not affect the menu text or text on the test patterns. It is interesting that the size of the rectangle corresponds to the area used to display text on the test patterns and that the lines precisely match the spacing of the test pattern grid.

Is it possibly a malfunction where whatever is used to display the on screen text is freaking out and showing these lines when it shouldn't be showing anything?
I did try toggling the "Status" option which suppresses some of the on screen text but that didnt change the behavior.

Full Resolution Image - 631KB

AVI Video (Right Click Link and Save) - 50MB
Ignore the ground loop line - thats just the sync between the projector and the camera.
post #2 of 19
Kris, I have the exact problem. No one posting had seen it before here or at Curt's site..
Here is the link to the thread I posted pics.
Curt has my YA board he is working on now so hold off to see how he makes out.
I'l keep you posted, Alan
post #3 of 19
This does indeed look exactly like Alan's problem. I've worked over his board about 3/4 of the way at this point, and will put it in a set tomorrow. I'll report how I make out..
post #4 of 19
Great timing if it turns out to be the same issue.
post #5 of 19
So far the board here is working. I want to run it overnight and will actually watch a movie tonight on badly text burned tubes (!) and I'll post tomorrow once I'm sure this is the fix.

PM me or email me if you want to send your board in.


post #6 of 19
Thread Starter 
You rule!

I love these forums.
post #7 of 19
Boo, I spoke too soon! They are still there. I think they are less present, but still there. Time to rest tonight and out with the big guns (pun intended), the oscilloscope tomorrow!
post #8 of 19
Thread Starter 
I was able to pick up a second G90 for parts this week. :-)
Its a high hour machine and the tubes are pretty worn, but it seems to work fine and I wasnt able to see any of the issues I've seen in other G90s.

Once I get it home I'll swap the YA boards and see if that resolves the issue at hand.

A while ago in another thread it was suggested that the YA and YB boards were somehow matched and should be kept together. Does anyone know if that is indeed the case?

Since I have both I'll probably keep them together just to be on the safe side, but I'm wondering if its true...
post #9 of 19
You can swap YA boards in a G90 no problem. However, the FW versions must be the same between the two YA boards, you must swap Dallas chips, and neither board can be in simulation mode (though I have never seen a G90 that has been in simulation mode unless I put it there).

BA boards can not be swapped between projectors without recalibration of the projector and possible the BA board drive trimmers.

post #10 of 19
I talked to Curt today and he thinks he has figured out the problem with your two boards. However, the part is not available anymore.

I do have one of said parts here and could fix one of the YA boards with it... assuming this is the problem and nothing goes wrong during the repair.

post #11 of 19
Thread Starter 
Any thoughts on the root cause? The IC going bad just by itself over time, or something else in the system damaging it?

I'm thinking of maybe swapping the projectors and putting my tubes in the new one.
post #12 of 19
Kris, Great to hear you were able to find a parts machine, I was able to find one also and should have at the end of next week. Let me know how you make out with the Dallas chip swap.
This adds another chip to unavailable list and both on the YA board.
post #13 of 19
The good thing is that I can mix and match chips between YA boards

post #14 of 19
Also, if anyone with this problem is willing to donate their YA to me I would appreciate it. So far this is just a theory and until I try to repair one of these we won't know for sure.

post #15 of 19
If anyone wants to chime in on this problem that is still unsolved, please see this thread [LINK].

post #16 of 19

I put 30+ hours into finding the problem, but I got Alan's YA board fixed today. If anyone wants this fix in the future I will be happy to provide the service. You can email me craigr@cir-engineering.com and I'll provide prices and shipping instructions.

I am also always happy to take on other YA and G90 repairs on board level.

post #17 of 19
Craig, you're the man! Hats off to you for solving another problem.
post #18 of 19
Thread Starter 
Just wanted to report that my YA board was repaired by Craig and all has been well since then.

post #19 of 19
I also have to report that Craig fixed my YA board with the same issue. I have been out of loop for a a few weeks taking care of my wife after having surgery.

Craig did a great job and took alot of time to diagnose the problem! Another issue resolved to keep the G90 alive.
Thanks Craig!
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