• Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.

Macintosh SE FDHD problem :P

Good morning/good evening.
Here I am for the news:
I took apart the Sony power supply and double checked the voltages and electrolytics, used a couple of voltmeters to verify that the voltages were present at the same time as the power up and everything was running consistently. I also checked the -5V obtained on the analog board from the -12v coming from the power supply, and that works fine too. Finally I looked for the peaks with the oscilloscope but all the voltages seemed "clean" to me. This is what I managed to do in this period, in the meantime I ordered the ceramic capacitors from lopgica (104z and 103z) which I will mount as soon as they arrive.
For now, Happy Easter everyone from me and the SE with its Easter Egg!
 

Attachments

  • +12.png
    +12.png
    4.5 MB · Views: 8
  • 5v.png
    5v.png
    5.2 MB · Views: 4
  • -12v.png
    -12v.png
    4.2 MB · Views: 4
  • -5v.png
    -5v.png
    3.5 MB · Views: 4
  • IMG_4481.JPG
    IMG_4481.JPG
    2.2 MB · Views: 8
Update: Good news, it's Fixed!
So let's see what happened: while waiting for the small 100 nf capacitors, however indispensable because I found others with rusty legs, it occurred to me that I had seen some small black spots on the Rom's feet, I decided to clean them with a sheet of 800-grit sandpaper.
The little SE started working again! Rows disappeared on startup.
Perhaps I should have focused more on ROMs and the flaws connected to them.
Also the other integrated ones had stains on the feet, 30 years and more are not a few for a correct conservation.
Perhaps some dirt was also found in the socket of the integrated circuit.
Also, the machine must have been stored in a humid environment which severely damaged some parts.
A final example was the failure of the internal clock: the capacitor C18 connected to the quartz Y1 had a broken leg from the oxide. At the moment I have replaced it with a 33pF 10% disk ( J ) but with 6Kv of isolation. I had nothing else.
The clock works, but the capacitor will need to be replaced with something more accurate and 50V.
In the end I hope that my experience can be useful to those who find themselves in a similar situation.
Happy continuation everyone!
 

Attachments

  • blue 33pf.jpg
    blue 33pf.jpg
    900.8 KB · Views: 5
Top