Hello, this is my first post here. I've some old macintosh computers (not too much, only an SE 1/20, an LC II to be repaired and an IMAC G5) and now I've a Macintosh Plus but it has an small-big problem, the computer turns on but there's an issue on CRT screen, do you know what could be the problem and if there's any solution?
As you can see, below the lines it's possible to see, very poor in the photo, the Macintosh Disc error
And, when I press interrupt button, it's shown this:
Thanks a lot for the information. I've seen, using your reference , that there's a capacitor inflated so I think that it could be one of the problems. I'm trying to look for it because it's not very common in my area. I'll let you know it that's the problem. Thanks!
The horizontal problem seems to be solved, Now I've this in the screen, I'll continue checking the analog board and the connections. There're extrange things that happen. If I remove part of the memory banks the image is a bit different and if I remove/move a bit the 3,9uf 35V capacitor (really, I changed by a 4,7uf/50V non polar capacitor) sounds the "bong" of the start... I'll continue checking and let you know after this weekend.
I was trying things, reviewing all the contacts in the analog board and I think that the problem could be the small HD74LS38P PIC because I've desolded the 1st pin (5 volts pin) and the MAC runs (I can hear the "bong" sound and the disc drive stars moving) but there was nothing in the screen... it was strange but when I do contact between the board and the 1st pin suddently the computer is "blocked" but I can see the screen again... Do you know what could be the problem??. I've purchased the HD74LS38P to try to change it but I'm still not sure if that is the problem. Thanks!!
