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  1. I used isopropyl alcohol when I disassembled the drive for a more thorough cleaning but it never convinced me that this could be the cause of the problem. It looks like that damned disk brought the floppy drive head out of alignment. Generally this is possible, but only in the writing phase when a copy is being made from an image disc where the latter has been done bypassing the physical movement limits of the head. In fact, one should always check how the image copy of a disc was made (especially when we download files from the internet). But it is not my case since the burning software is native to the operating system and I do not make any copies from the disk image.
  2. I have a problem with the floppy drive .... I have many HD floppies and I would like to try to make a selection to understand which are still usable and which are not. I started to format them with a Power Macintosh 7200 ... all right ... some working floppy and some floppy with some bad sector, until I found a cursed floppy. Why will you say? Because after trying to format on this floppy disk my Power Macintosh gave me an error and from then on it was no longer able to complete a format (not even its floppy disks that I was able to format correctly before). More precisely, inserting a floppy that had previously formatted, it tells me that it does not recognize the floppy and asks me if I want to format (Mac, ProDos, Dos): I tried all three types but in the end it does not complete any type of formatting . I have two Power Macintosh 7200, so out of curiosity I tried to format floppies with this second mac, all right, it manages to format HD floppies at 1.44 Mb (those that I could no longer format with the other Mac), but at a certain point I inserted that damned floppy and it caused me exactly the same anomaly as the other Mac. Now I am with two Power Macintosh 7200s that are no longer able to complete a format. Some idea? I tried to clean the head but nothing ....
  3. Hi guys, I just wanted to tell you that I managed to fix the Apple HD 20 SC. Here's what happened: the HD had a pre-installed System inside (I don't know which version and I don't know on which machine it performed the installation). It was therefore a bootable HD and (oddly), any selection of the SCSI-ID was not taken into account and made me boot always and only from the HD 20 SC. So I put a System 6.0.8 bootable from Floppy on the Macintosh SE to boot from floppy (the Macinotsh gives priority to the floppy to boot, then to external HD and lastly to internal HD. At least for that's me). So, started the System from Floppy I was able to see also the HD 20 SC, and from here I removed the installed system. Seeing no boot disk from the HD 20 SC, all my macintos manage to see it as secondary. I mainly needed it as HD for my plus. So I connected it to my macintosh plus and started from floppy (System 6.0.8), from here I installed the 5 floppies on the HD 20 SC. The reason why my Plus didn't see the HD 20 SC was because you actually need to turn on the HD 20 SC first and then the Plus; my problem was that the plus was trying to boot the system from the HD 20 SC, and it was definitely not compatible, that's why it kept restarting. Thank you very much for all for your interest
  4. Yes exactly! what I tried. considers that HD works, because when I connect it to my Macintosh SE, it immediately starts with booting from the HD20sc. unfortunately I can no longer dictate the hd20sc so that it starts but as a secondary. always starts as primary. note: the adapter you see between the SCSI cable and the HDD connector is necessary, otherwise I cannot insert it!
  5. yes exactly Crutch, it is a terminator and from what I have read around it seems that this type of hard disk (20 SC) needs the terminator if there is no other device connected. Anyway I tried to disconnect it but equally my plus does not recognize it. I have to turn on the HD when the plus recognizes the boot floppy, otherwise it goes into a loop and continues to reset, but in any case on my desktop I don't see the HD icon. I have not understood what you mean jessenator... Trash80toHP_Mini, I'm sure it's the original disk because I disassembled it from an Apple case with still the seals. I was able to view the HD 20SC from an SE as a second HD (not as a primary) only once; now in any way I start it, my SE sees the HD 20SC as primary and tries to load the OS from it but crashes because the SO of the HD 20SC was installed with the previous Macintosh and I don't know what model was. I have tried in all configurations (ID selector), with and without terminator.
  6. I tried with both the System 3.2 and the System 3.3 following the procedure you described but unfortunately I don't see the HD in the finder. maybe I need the floppy called HD 20 startup?
  7. Thanks Crutch, I immediately tried the configuration as you told me but my Macintosh Plus (turning on the HD first and then the Macintosh), does not start, or rather, starts but then resets immediately after to continue so indefinitely . I have tried HD with a Macintosh SE and it works. You told me it should present problems if I turn on the HD after turning on the Macintosh Plus, but oddly enough it gives me problems if I turn on the HD first and then the computer. I tried to turn on the macintosh plus first and then the HD but I don't know how to make it read
  8. A few days ago they gave me an original Apple 20 external HD as in the picture. With the HD I also have the terminator and the scsi cable. In the absence of documentation, I don't know where the terminator (below or above?), and the connector, goes. Then there is a number near the connectors where it is currently set to 5. Can you tell me the exact configuration? If everything goes smoothly, once the computer starts, will it automatically recognize the HD? Thank you
  9. Roberto

    Macintosh SE 30 display half screen

    thanks, I will give a general cleaning and maybe a new welding point and then eventually I will change those two components
  10. Roberto

    Macintosh SE 30 display half screen

    Bolle, do you mean these two?
  11. Roberto

    Macintosh SE 30 display half screen

    Thanks Bolle, for your interest, I think I'm sure it's the logic board because I tried to change the analog card (including the card that goes behind the CRT tube), and the problem is exactly the same, so I conclude that both the logic card and the cause. Today I will change the two 74LS393 as you would like. However I have not done any kind of recap regarding the logic board, even if it seems to the naked eye that the board is perfect.
  12. Hi everyone, I'm new to the forum and I hope to be in the right place for the help you want to give me. I introduce myself here, since I honestly didn't find the presentation area. My name is Roberto I am Italian and for some time I would like to fix my macintosh SE 30, which has an unusual problem, that is, you only see half of the lower screen. It is very strange because, according to what L. Pina writes in his book, it is not a part of the screen that collapses (in fact, the horizontal central line is not visible), this last problem is in fact due to a problem of the analog card. Here instead we see a part of the screen that is missing and has not collapsed. I tried to replace it with another analog board and the result is the same, so I assume it is to be attributed to the logic board. In the logic board I haven't done any intervention at the moment. Has anyone experienced such a thing? I thank all those who want to make their contribution to understand where the breakdown is.