MBP & 30" Display sparkling

[bpd115]

So I sold my 2 x 2Ghz G5 since my MBP was just as fast and used the money to purchase a 30" Cinema Display refurbished. All seems fine at first but I notice on black or dark screens I am getting horizontal pixel flashes at random. I have set up a replacement with Apple (I have noticed 3 dead pixels but that's minor).

I have ran the video test in TechTool and the Video ram passes fine. The laptop also drives a 23" ACD no problem.

Reading the forums though it seems this is common with the MBP? Anyone have a cause or solution? I had my MLB replaced for the whine (which is finally gone) a few weeks ago. I saw some reports of this on Macfixit.com but you have to 'subscribe' to read the article and I'm not paying 24.00 to read a forum.

Help!!

 

[vv-tim]

When I first read the title I thought you were saying that the Apple Cinema Display had dithering... that's usually what people mean when they say the display is "sparkling".

As for the horizontal flashes, there are two possibilities. There's a slim possibility that your refresh rate is too low and you're catching a glimpse every once in a while as the screen refreshes. The other possibility is that it's a bad screen...

I don't imagine that its the MBP at fault, but I suppose it's always a possibility.

 

[gekko513]

No, it's not likely that it's the screen. It's much more likely to be an issue with the cable and/or the MBP.

I've used a 23" Cinema Display with my MBP and it also sparkles, but the display doesn't sparkle with the PC that it's normally connected to. I've also tried the MBP with a 1600x1200 Dell display and it looked OK on that. I have to conclude that it's either the cable+converter that I used for the 23" display, or the MBP doesn't handle high resolutions well enough.

I'd try connecting the MBP to the display with a different cable and to other displays if you know anyone else with high resolution displays.

 

[Scottyk9]

ok, here is my experience, which I am currently talking to Apple about

MBP 2.16 with 256VRAM
1st 30" ACD - green pixels readily apparant on even the blue OS X backdrop, but not always present. "Flashing" pixels visible on black background. Called Apple - declared DOA, sent out new replacement.

2nd 30" ACD - ok with colored background, but short one pixel width horizontal lines visible with black background - mostly red, some green/white (sounds just like the problem you are having). Discussed with Apple who suggested "fix" of using in extended desktop (not clamshell). This improved but did not solve the problem. I find this very distracting, as these really draw your eye (a problem if you are working on a photo with a black background, and distracting if watching a movie clip or DVD).

My other tests - same problem when using a black desktop in windows xp (boot camp). However, works perfectly with a 23" ACD.

Now in at local Apple dealer. Initial response was that there was no problem when using their own MPB. They were nice enough to take the time for me to bring in my MPB and show them the problem - which was obvious to them in both clamshell and extended desktop. They thought it might be the MPB (specifically the GPU), but then we tested it again with their MBP (more recent than mine) - although not nearly as bad as with my MPB, the same problem was seen with the 30" and their MPB in both clamshell as well as extended desktop (although the problem in extended desktop is so rare that it could be considered to be very close to "within normal limits").

This last test was just today, the store will be contacting Apple to see what happens next. My concern is that the source of the problem is not clear:
- it happens with both windows and mac OS drivers (albeit on the same machine)
- a similar problem has occured with 2 recently manufactured 30" ACDs
- although the magnitude of the problem differed, it could be replicated on 2 MPB (one which is the "latest", which I understand has an improved logic board).

I really wish there was a simple fix (using the 30" is fantastic, but I find those flashing pixel lines very distracting - my eyes are drawn to it). However my observations so far are not very encouraging, and don't point to one source of the problem.

I would be VERY interested to know if anyone has a working MPB and 30" ACD (tested by using in clamshell mode with a completely black background - should be apparant within a few minutes). Anyone willing to help us out?

 

[gekko513]

I knew I had read somewhere that this could be a cable problem:

Kunal Kapoor
The purple speckling affect around windows on the 30" display are because of a poor quality DVI cable. I have experienced the same problem and changing the Dual Link DVI cable got rid of the Purple speckling affect
This has been a problem on both the Apple 30" and the Dell 30" display. It seems like there was a bad batch of these cables.

Link

 

[Scottyk9]

I knew I had read somewhere that this could be a cable problem:

Link

Yeah, I wonder if these are 2 separate issues - my first display had sparkling green dots readily apparant on pictures (they would often congregate along contast lines, and move with moving windows), whereas the latter is more like a subtle "interference" pattern that you can only really see on a black background.

You may be right though, but you can't change the cable on the 30"ACD - you have to get a new display.

Edit: from that link you provided, the few reports regarding flickering pixels on the 30" don't sound encouraging....

 

[gekko513]

Aha, I didn't know that. So in that case the display will have to go in for repair if it's the cable's fault.

 

[bpd115]

Well, I've sent the display back this AM and will call them to ship the replacement as soon as the tracking info shows up on the Fedex site. If it happens with the replacement as well then I'm going to take my MBP to an Apple store (an hour 1/2 drive) and see what's up there.

I bought the display to use with my MBP until April when I purchase a Mac Pro. I just had my Logic Board replaced for the whine fix so it should be the lastest revision.

Apple should have really made the cables on the ACDs detachable. It would have saved them lots of headaches I'm sure, as well as ourselves.

Someone reported on the Apple forums that it doesn't happen with their 17" MBP but does with their 15". The only difference is that the 17" ATI Card is clocked a bit higher than the 15". If the maker of ATIaccelerator II would just include the X1600 so we can test how over/underclocking the card effects this issue....

 

[Scottyk9]

Just got the 30" ACD back from the Apple authorized service agent. Apparently they have a contact in engineering at Apple who they spoke with regarding this (this is not the usual process, I was told), who stated the following:
- Apple has acknowledged the issue, and is working on a fix. As usual, there is no ETA for the fix, and no guarantee that a fix will ultimately even be possible.
- there is a workaround that Apple is suggesting:

1. connect the DVI to the MPB in clamshell mode, allow it to detect
2. Open notebook, then detect display (extended desktop)
3. then unplug the DVI, allow OS X to adjust the display
4. Reattach the DVI and detect display
5. Put in clamshell and re-awaken (if you do not want to use multiple monitors)

Whew! yes, it is a hassle. Does it work? Well, I have only tried it out for a few hours (using a black background, mostly playing around in aperture), but here is what I have found:
- it does appear to solve the problem if you leave it in multiple monitor mode
- it does not solve the problem when in clamshell mode

This is disappointing for me, as it is only really feasible for me to use clamshell mode in my setup (and, I prefer one large screen, as well as keeping all the VRAM for one display instead of split between 2).

Sounds like there is no other information or suggestions from Apple at this point, although it is encouraging to hear that they have acknowledged and are working on it.

For myself, I think I might have to call Apple again and perhaps return the display (a huge disappointment....)

 

[bpd115]

Thank you so much for the update Scott. Needless to say I got the replacement 30" yesterday and saw the same issues (although this one seems to be newer and I see no dead pixels).

I guess this effects every 15" MBP? Huge gaff on Apples part as they advertise the laptop to support the 30" display. I think it may have something to do with the fact that they underclocked the GPU.

I have my laptop docked below the display so I guess I can use it in extended mode and just use the laptop display as a dock/pallet window for now. If infact the fix you posted works for extended desktop mode I find no reason why they couldn't fix this in software to work for clamshell mode.