Apple Macintosh 16" Color Display Issues

[jmacz]

I picked up a 16" Apple Macintosh Color Display yesterday at an e-waste center. I have it connected to a Quadra 700 (fully loaded on vram) and saw a few issues. I'm creating this thread as I read through a bunch of threads (both on this monitor and similar ones) and couldn't find answers that matched what I am seeing. Any help would be appreciated. Note that the display is running at 832x624 at millions of colors.

Issue #1: Focus

The focus isn't great. I have left the display on for more than 20 minutes and it doesn't get better. It's not like it's illegible, it's just a little soft. Not sure if it's because I'm staring at a modern retina MacBook Pro all day and being anal, but I can't remember how sharp these Trinitrons were back in the day. Trying to decide whether to open up the monitor to play with the focus adjustment pot. I have the service manual but I have never opened up a CRT before so even after watching various videos, still a bit concerned about doing so. You can see it a bit in the picture below for #3 by looking at the menu text.

Issue #2: Noise

There's vertical noise (horizontal lines moving up/down) on the screen. It's feint but noticeable. It's mainly in the lower portion of the screen. Bad shielding? Not sure what can be done about this. Is this an indication I need to have this display recapped?

Issue #3: Creeping Shadow

There's this weird dark spot (stretches the entire vertical length of the screen) that slowly creeps in from the left side of the screen. When I turned on the monitor it wasn't there. It then slowly appears and takes about 5 minutes to creep right across the screen and completely blacks out a section of the screen about 1" wide and full length. It then starts slowly creeping back towards the left (another 5 minutes) and disappears. The screen is then clean. But then this happens again about 10 minutes later. I have a picture of it below. Any idea what could be causing this?

 

[finkmac]

My 16" colour display has a similar issue with the focus. In my case, lowering the brightness increases the sharpness.
I did pop it open and adjust the picture a bit which helped focus it a bit, but I think the boards need a recap.

Most Sony PVM boards are in need of capacitor replacements these days, so this isn't surprising.

That being said, I think it's a combination of various factors, including us being used to sharp modern LCDs. To my knowledge, colour displays were always more blurry than greyscale/monochrome displays.

As for issue 2 and 3, I'm not sure. Issue 3 looks like a geometry issue in the image. Does the picture distort as the black spot move?

 

[jmacz]

Thanks for the response.

No, the picture doesn't distort in the area of the shadow. It's almost like something is blocking the light and starts sliding about 1" from the left side (ends up covering about 1" of the screen) and then starts sliding back the other way and goes back to normal. The edges of this shadow is feathered (as you can see in the picture) - it's not an abrupt edge, it's gradual. So it really looks like something is blocking the light. It doesn't get worse or better as I tilt the screen or nudge it, so doesn't feel like it's something loose inside that's blocking anything. Really weird.

 

[jmacz]

Anyone have the capacitor list for this monitor by chance? m1298.

Opened her up today and took both boards out. No corrosion anywhere, no bulging caps. Someone did open it up before me though as four screws were missing as well as two copper grounding plates for the EMI shield.

The video cable’s braided shielding sleeve was grounded differently than in the service manual. The manual shows a grounding cable coming off the cable near the 10pin connector. But my monitor has a copper clamp around the braided shielding that was screwed into the sheet metal (looks factory). There’s also an odd clump of the braid near the 10pin connector that looks sheered …

I used an ESR meter to check all 27 electrolytic caps on the smaller video board, 2 of them seemed out of spec, the rest seemed ok. But I am going to replace them all.

Will look at the main board next weekend. There’s 60ish more caps on that one. Ugh.

 

[jmacz]

Recapping resolved issues #2 and #3. Focus still isn't great but having now compared it against other CRTs, it's just me getting used to the sharp modern flat panel displays.

 

[jajan547]

I uploaded the service guide for a few apple monitors, lucky for you the one you have is listed. I have linked it HERE for you and you'll want to start at page 211.

 

[jmacz]

Thanks, had not seen that particular guide before although I had access to another one for this monitor. Already tried the focus pot per the guide you linked and doesn’t help. I think it’s just the age at this point.

 

[Big Ben]

Focus can be tricky to get, aging and the fact we are used to sharper displays make this hard to get right.

I did a calibration on my Classic Color, I never had a sharp focus across the whole CRT, I had be between two spot: sharp edges or sharp center.

Same as you, I can't recall how good where those CRT, I just remember non-trinitron where kind of cheap compared to sony's back in the day and a little more blurry, I also remember old CRT at school being out of focus after few years.

EDIT: Just a thought but maybe color adjustment could impact focus?

 

[jmacz]

Yeah, I had the same thought (color adjustment) but those pots are super hard to reach on this monitor. It’s on the back of the video board and accessed through tiny 2mm diameter holes. Gonna try sometime soon.

 

[jmacz]

Ok the red/green/blue drive and background pots didn’t help. The sub bright and sub contract pots didn’t do much either. But I did find an undocumented pot on the fly back which can be reached from the side, this is different from the focus and convergence pots. This helped marginally. Will just have to deal with the fact that this monitor is just old.