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| Macintosh Color Display: How did I royally screw this up??? |
Posted by: LaPorta on 2022-06-04 21:27:48
So, I did a recap job on the Color Display. It basically went fine and I wasn't having any issues, other than the power jack seemed to be a bit loose. So, I pulled the board, and touched those up. While I was there, I noticed that the areas holding down the metal shielding to the ground track were flaky and cracking. So, I resoldered those as well. I suppose I touched up another connector or two also. I rechecked them after this...and saw no bridges or anything.
Once I replaced everything...now the thing doesn't work properly at all! Look at this nonsense, it seems like the flyback or something is all over the place. I can't get a good image of what it looks like, so I had to take a video (don't mind the background sound from a show I was watching).
I am so frustrated: what the heck could I possibly have done to screw up this perfectly working screen?? I am just so utterly discouraged right now...
View attachment IMG_3272.MOV |
Posted by: Byrd on 2022-06-04 21:38:53
! Not a nice sight after all your work - I'd be removing the case and gently tapping components, connectors with the end of an (insulated) screwdriver; you might find quickly what the issue is. Also check your anode cap is properly reapplied and the yoke connector. |
Posted by: LaPorta on 2022-06-05 19:37:06
Poking things did absolutely nothing, no easy fix. Pulled the board again, looked for anything I could. Touched up some solder areas, nothing major. Now, I get a relatively clear, stable picture that is totally red, like the blue and green drives are not there. As the monitor warms up, then the picture gets less stable and starts to collapse a bit on itself. At least it isn’t the garbles disaster in the video, but I still am not sure what is going wrong. |
Posted by: LaPorta on 2022-06-06 12:28:01
I guess I need to keep a calm approach and take a step back. I have looked this all over can cannot find what would be the issue. I will take some photos that others can take a look at as well. I am not sure why I would now be getting a fully red picture. I am not sure how I could have knocked the green and blue drives out. |
Posted by: Big Ben on 2022-06-06 12:34:02
Sounds like a bad solder somewhere. By manipulating the board you may have trigger a problem that was just going to happen anyway.
By replacing the caps, you may need to calibrate the display, I wonder if there is a service manual for this screen but they usually have instructions.
From what I see it looks like the CRT is being overdrive (white lines) there should be a potentiometer that allows to adjust that
Also the unstability maybe related to capacitor characteristics being too different from the original ones? |
Posted by: LaPorta on 2022-06-06 12:38:57
There is. The frustrating thing is that after I replaced the caps, it actually worked fine. It was only when I went to take a second look that I noticed some cracked joints...that was when all this started. Thankfully, after touching up some other areas and actually reducing some solder in other areas I repaired...the screen is relatively stable red. I will need to get a photo of it when I am home. |
Posted by: LaPorta on 2022-06-10 21:05:48
Ok, so...
I have stable video now after touching up some suspect areas. However, everything is still straight red. I fooled around with the cutoffs in the back and discovered that if I try up the red or the green, I get red or green contrast lines like how you would get just white ones if you turned the main cutoff too high (as one would expect). However, fiddling with the blue drive cutoff in the back up or down produces no effect at all. That leads me to believe that, for some reason, the blue drive is out. How/where to find that dedicated circuit and see what is up I have no idea. I also tried it with a different video card to rule out card issues...and I did rule them out.
I am attaching photos of the board from underneath, and one from up top. I also included what the screen looks like when in use. |
Posted by: LaPorta on 2022-06-18 21:34:12
Anyone able to chime in here? I can't find a darn thing wrong with it from a visual standpoint, and so far the actual components I tested test ok. Just not sure where else to go. I hate thinking I ruined this thing. |
Posted by: jajan547 on 2022-06-18 21:41:00
Two things, can you record a video of it running in a dark area with the flyback showing. Secondly I think it could be a color drive issue, Perhaps the small board on the back of the CRT? |
Posted by: chiptripper on 2022-06-19 00:52:13
Could try cleaning PP1 and other pots with isopropyl / contact cleaner, turn them back and forth. Probably not the issue though.
CL6 in the top right of pic 3 looks odd.
I don't see any flaws in your work. Given the circumstances my instinct says loose cable connection or flaw in the wire itself. |
Posted by: LaPorta on 2022-06-19 09:50:12
I will get the video this afternoon. It is frustrating only beacuse it worked just fine without issue previously! |
Posted by: LaPorta on 2022-06-20 04:55:59
My apologies, I got so busy that I was unable to get the video. |
Posted by: LaPorta on 2022-06-23 23:09:21
After a long wait, here is the video: |
Posted by: LaPorta on 2022-06-23 23:18:49
After fiddling around a bit more, I find that I do indeed get red, green, and blue lines when the R-G-B brightness pots are adjusted. So, all three electron guns are working. I wondered then if the signal is not coming in. Could this be from me tugging on the cable too much each time I work on it? All the main cable pins appear to at least have continuity with some of the monitor connector...not that I know which ones it should have. I have tested this with two different video cards that work with other monitors, so that is not the issue. If the signals are missing, and it likely is not a cable connection, what could it be? |
Posted by: LaPorta on 2022-06-24 20:51:40
Not sure if someone might know how to actually scope the different video signals at different points...perhaps that would help? |
Posted by: LaPorta on 2022-07-08 13:59:17
So as this actually gets worse and worse the farther I go, I am thinking I will ultimately just take this to the local eWaste recycler. I just wish The thing had worked out. Not like these are being made anymore. |
Posted by: 3lectr1cPPC on 2022-07-08 14:07:42
Ugh, I absolutely hate it when stuff like this happens! You take something that works fine, do some cleaning or maintenance to prolong its life, then it doesn’t work after! That happened when I did some cleaning on my Power Mac G5 back in 2019, just to have it quit starting up after. I had to replace the logic board.
I wouldn’t toss it if I were you. The case pieces could still be of use to someone else, as well as other parts. You might also figure out the problem after taking a break for a while, sometimes taking a step back helps! In any event, something is wrong with it, something that can likely be fixed. It hasn’t been run over by a steamroller, and as you said, these aren’t being made anymore. |
Posted by: LaPorta on 2022-07-08 14:08:43
The issue is that during my attempts, the gun appears to have burned in a small dot in the center of the screen. I can't fix a CRT for sure. I would certainly offer parts to anyone that wanted though. |
Posted by: 3lectr1cPPC on 2022-07-08 14:09:49
It’s probably a parts machine then, but with how easy the plastics are to break on these things I’m sure someone out there has a smashed but working one that yours could be a donor for.
Edit: Something else that might be worth noting. Ken from the Computer Clan on YouTube had a very similar issue to the first video you posted on his Color Classic. He never posted a follow up so I don’t know if he got it fixed or not, but here’s the link if you’d like to check it out: |
Posted by: chiptripper on 2022-07-09 14:53:38
Sorry to hear this, I wish there was a larger body of knowledge for these Trinitron boards. I've had similar unresolved issues on M1212s and several color classics and they're mystifying. It's usually either a bad connection somewhere along the video signal or voltage issues, but at this point I'm thinking it might be a chip failure. Somewhere like reddit.com/r/crt might have some insights.
I'd be interested in the flyback, if you decide to junk it. |
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