[Older] ACD screen going nuts

[swindmill]

I have a 20" ACD (the G4 style) and last night it suddenly started acting up. It's hard to describe, but there is a light blue tint covering parts of the screen and it jumps around. I tried to take a screenshot, but it doesn't show it. Any idea what is wrong or what steps I can take to diagnose it? It does not happen on my pb's screen, which is what it is used with.

Since the screenshot didn't show it, I should add that it is very noticeable and makes it hard to even use the screen. The blue tint flickers and flares and covers most of the screen at any given time.

 

[swindmill]

I hooked it up to a mbp and the picture was fine. So, it's a problem with my powerbook. The picture on the powerbook's lcd is fine. Any idea's?

 

[Makosuke]

Sounds like a bad connection to the powerbook to me; in my experience with bum graphics cards, the artifacts DO usually show up in screenshots because of the way OSX handles that. Similarly, were it somehow software (which seems highly unlikely) it should be in the screen shots.

If it's fine with a different computer, that pretty much only leaves the connection on the PB or something in the graphics circuitry. Since it doesn't show up in screenshots or the internal screen, that seems to point to bad wiring, either at the connection itself or somewhere between it and the graphics card.

No suggestions as to what to do, but see if moving the connector around changes it--if so, maybe it's just the port and can be kludged somehow. If not... bummer.

 

[swindmill]

The only difference in the connection used with PB and MBP is the mini-DVI adaptor. I've messed around with that and the connection to my PB to no avail. It may be that the PB needs to opened up to fix a connection inside. I don't know how the graphics card works, but I thought it was maybe possible that the signal going to the external monitor could be bad, while the internal signal is fine. Again, I know nothing in that regard. At this point, I would describe the problem mostly as having a blue and red tint to everything, especially on lighter backgrounds. If I use a a very light desktop, it is practically covered in a flickering blue tint, but not noticeable at all on a black desktop. Any other thoughts or suggestions are appreciated.

EDIT: I hooked up a CRT to my PB and the picture was just fine. So, other monitors work with my PB, and my ACD works fine with other computers. I'm not sure what that leaves??

picture from my camera, since it doesn't show on screenshots:

 

[Makosuke]

If I'm understanding your setup correctly, the difference is that a CRT uses VGA (analog) output, and the ACD uses DVI (digital) output. If it's bad wiring either on the motherboard between the graphics chip and the port, or within the port itself, the it's entirely possible for one to be flaky while the other is fine.

A better test would be to find another DVI monitor somewhere and try that. If THAT is fine, then it's either a weird combination of problems or the adapter is bad somehow.

 

[swindmill]

I'm should be able to get another mini-dvi adaptor and a different ACD this weekend to try out.

The VGA output did work just fine, so maybe it is the digital ouput