As someone who has a gaggle of LCs, I also have a ton of these matching monitors. I have a few observations and also some questions pertaining to the feasibility of fixing these monitors.
First, there are actually three variations of these. The earliest ones made in 1990 and into early 1991 seem to use a different assembly for the CRT. Apparently there's also a slight difference on one of the boards with a coil being present or absent at VR504. The no-coil ones are the earliest variants. The newer model went into production around the spring of 1991 and seemed to be made throughout the rest of the year. The CRT itself was changed out in 1992 at some point for a new model with a red, white, and blue label. (The older ones have a turquoise label). The newer CRT needs a different voltage adjustment.
In general, I swap like for like with these and try to get replacement parts from a CRT with the same month and year of manufacture. For example, when my November 1991 M1296 had an issue, I replaced its boards with another M1296's from the same month.
However, there are some issues I've had with these and I want to know what the likely causes are and how well these could be repaired. I already am aware of the caps that need swapped out when the upper portion gets distorted and that if the focus goes out after 30 minutes that the flyback/focus unit is likely bad (shame they are all one unit), but I had the following take place in these monitors:
1. I have one of the 1992 monitors that seems to flicker sometimes. I'm wondering if it's drawing adequate power. It otherwise does fine, but it's one I'm a little concerned about long-term.
2. I have one that is also a 1992 model and it was working fine--good focus, good picture--and suddenly it started shifting the display and then there was a complete conk-out. No smoke, nothing like that, it just stopped showing anything. I feel like the flyback went on it. I do have a spare monitor with a not as good case to pull an identical working board from for now.
3. I have another one that, at a lab yesterday, made a pop when it turned on but otherwise worked fine. I hadn't had this one on in about 7 weeks and I know the closet was a little humid when I pulled it out, so I'm wondering if that was part of it. I do have yet another spare from its approximate date that I can pull the board from if I need to.
Usually I just pull working boards from monitors with bad cases or scratched CRTs to salvage these. (It's also why I buy up every working one of these I can find). However, I know there will come a time when I need to start looking into lower level repair rather than swapping boards, so any suggestions, especially for my aforementioned monitors, is welcome.
I'll have all three of those with me at the next lab event, including #2 since it will get repaired one way or the other.
First, there are actually three variations of these. The earliest ones made in 1990 and into early 1991 seem to use a different assembly for the CRT. Apparently there's also a slight difference on one of the boards with a coil being present or absent at VR504. The no-coil ones are the earliest variants. The newer model went into production around the spring of 1991 and seemed to be made throughout the rest of the year. The CRT itself was changed out in 1992 at some point for a new model with a red, white, and blue label. (The older ones have a turquoise label). The newer CRT needs a different voltage adjustment.
In general, I swap like for like with these and try to get replacement parts from a CRT with the same month and year of manufacture. For example, when my November 1991 M1296 had an issue, I replaced its boards with another M1296's from the same month.
However, there are some issues I've had with these and I want to know what the likely causes are and how well these could be repaired. I already am aware of the caps that need swapped out when the upper portion gets distorted and that if the focus goes out after 30 minutes that the flyback/focus unit is likely bad (shame they are all one unit), but I had the following take place in these monitors:
1. I have one of the 1992 monitors that seems to flicker sometimes. I'm wondering if it's drawing adequate power. It otherwise does fine, but it's one I'm a little concerned about long-term.
2. I have one that is also a 1992 model and it was working fine--good focus, good picture--and suddenly it started shifting the display and then there was a complete conk-out. No smoke, nothing like that, it just stopped showing anything. I feel like the flyback went on it. I do have a spare monitor with a not as good case to pull an identical working board from for now.
3. I have another one that, at a lab yesterday, made a pop when it turned on but otherwise worked fine. I hadn't had this one on in about 7 weeks and I know the closet was a little humid when I pulled it out, so I'm wondering if that was part of it. I do have yet another spare from its approximate date that I can pull the board from if I need to.
Usually I just pull working boards from monitors with bad cases or scratched CRTs to salvage these. (It's also why I buy up every working one of these I can find). However, I know there will come a time when I need to start looking into lower level repair rather than swapping boards, so any suggestions, especially for my aforementioned monitors, is welcome.
I'll have all three of those with me at the next lab event, including #2 since it will get repaired one way or the other.