• Hello, Guest! Welcome back, and be sure to check out this post for more info about the recent service interruption and migration.

Search results

  1. goerz

    Recapped Macintosh Classic with checkered screen

    Thank you for the detailed information. In other news, this morning I switched it on for the first time in two weeks, and it worked! I don't know what happened: I turned it on several times during the day, and it always worked. The voltage is rock solid at 5.071V.
  2. goerz

    Recapped Macintosh Classic with checkered screen

    I've already replaced QP2, I'll check DP13 as soon as I'll resume this project. Could you help me identify the correct diode to order as a replacement? Thanks.
  3. goerz

    Recapped Macintosh Classic with checkered screen

    I think I have. I'll reflow it again, just to be sure.
  4. goerz

    Recapped Macintosh Classic with checkered screen

    I have already replaced the optoisolator and diodes DP3 and DP4, to no avail. I also replaced the voltage regulator. So the plot thickens...
  5. goerz

    Recapped Macintosh Classic with checkered screen

    I'm not sure I want to try that :) My board is a 220V version by the way.
  6. goerz

    Recapped Macintosh Classic with checkered screen

    Unfortunately, I haven't solved the problem yet. My parts list seems to be fine because the second analog board is working well now after replacing the TDA4605 chip (I hadn't it replaced initially because it's expensive and difficult to source for me). So the part causing the problem must be one...
  7. goerz

    Recapped Macintosh Classic with checkered screen

    It's definitely a problem with my parts list: I just recapped another Classic board this week with the same parts, and I get the very same problem. I have a working board I recapped in August 2021, so I compared the August 2021 parts list with the June 2022 list. There are some differences, due...
  8. goerz

    Recapped Macintosh Classic with checkered screen

    Yes, I replaced all capacitors on the analog board, along with the DP3 and DP4 diodes, TDA4605, CNY17G, the IRBC40 mosfet, and the PP1 voltage regulator.
  9. goerz

    Recapped Macintosh Classic with checkered screen

    So I checked the resistance of the RP2 thermistor and it's exactly 20 ohms when cold, so it can't be the culprit. I replaced the PP1 voltage regulator and for a moment I thought I solved the problem, but then I realized that the board was probably still heated because of my soldering. In fact...
  10. goerz

    Recapped Macintosh Classic with checkered screen

    Not as dramatically: the voltage starts at 12.18v, then it reaches 12.42v in about five minutes.
  11. goerz

    Recapped Macintosh Classic with checkered screen

    I read the thread you linked, PP1 could indeed be the culprit. However, it kind of works, meaning that it does adjust voltage as desired. The maximum voltage I reach once it is stabilized is affected by pp1. I'll try to clean it and in the meantime I'll order a replacement.
  12. goerz

    Recapped Macintosh Classic with checkered screen

    Thank you for your reply: yes, the voltage stabilizes much faster once the computer is warmed-up, even after switching it off. I did replace all the capacitors, including the high-voltage ones (btw, it's a 220v board). I'll check the NTC device you mentioned.
  13. goerz

    Recapped Macintosh Classic with checkered screen

    I'd just add more info, in case someone can help me. As I wrote, the voltage starts at 4.4, then it slowly increases. When it gets to 4.85 the pattern disappears and the computer boots, however, the image wobbles visibly. In about 5 minutes the voltage reaches 5.15v and then it stabilizes. At...
  14. goerz

    Recapped Macintosh Classic with checkered screen

    It's 12.68v. But I was too quick to call the issue solved: the screen reverted back to a wobbling stripe pattern, with no startup sound, once I switched on the computer after a few hours. However, after four or five minutes it warms up, then disk icon appears and it boots. Now I tested for an...
  15. goerz

    Recapped Macintosh Classic with checkered screen

    So I fiddled with pp1 and I managed to get 5.1v: the issue is solved, the Classic now boots. However the screen "trembles" for a while, then it stabilizes. I need to perform more tests... Thanks.
  16. goerz

    Recapped Macintosh Classic with checkered screen

    Thank you: I turned pp1 all the way up, and I got only 4.6v. Moreover, the screen wobbles and the pattern changed to what you can see below.
  17. goerz

    Recapped Macintosh Classic with checkered screen

    I get 4.5v on the external floppy port and 11.78 on the hard drive connector. I have already replaced the TDA 4605.
  18. goerz

    Recapped Macintosh Classic with checkered screen

    Hello, I recapped a Classic with capacitor damage on the analog board a few weeks ago (logic and analog board). Everything worked fine for a while, but today this pattern appeared on my monitor. I managed to narrow down the problem to the analog board (I swapped it with another one and the Mac...
  19. goerz

    BlueSCSI naming convention question

    I use my BlueSCSI with a Macintosh SE without issues. I've never paid too much attention to SCSI IDs: I have 4 or 5 different volumes in the same memory card, I just make sure they have different IDs. Their order does not seem to matter, in my experience.
  20. goerz

    Recapped Macintosh Classic's screen wobbles when cold

    Thank you for your replies. I measured the voltage after a cold start and it seems fine to me (5.046V and 12.18V). It remains almost the same once the Macintosh warms up and the screen issue disappears.
Top