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About MacinPosh

  • Birthday January 20

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    London, UK

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  1. Following up on this after a long time. After a lot of head scratching and component swapping, I went back to basics and discovered that the problem was in fact with two capacitors on the Hard Drive's analog board that had gone short circuit. (Shown in the RED box in the photos, compared to the original in the GREEN box) After replacing them, the drive span up and "promptly" booted to MacWorks. I learnt the typical lesson of check for the common simple issues first!
  2. MacinPosh

    Profile Power Supply Blown Resistor

    Unfortunately I don't think that's the correct schematic for the board. The component is from the small daughter board connected to the Astec Power Supply AA11770
  3. Inspecting the Profile power supply board, I noticed a very burnt resistor that had cracked into two pieces. I'm having trouble identifying its value. Can anyone help me out? It looks like Brown-Grey-Orange-Grey-Brown? Thanks
  4. I recently acquired a 5MB ProFile drive in an unknown condition for use with my Lisa. I promptly replaced the power supply caps in hope that the drive would be operational. Powering the system on resulted in a high pitched whine but nothing else, but when I disconnected the internal data cable between the controller board and the hard drive, it did begin to spin up. Any suggestions on what to try next? I've tried reseating all the chips. Are any particularly prone to failing? Is there any way to narrow down whether the controller board or the drive analog board is at fault?
  5. MacinPosh

    Mac Plus Horizontal Line and Speaker Noise Boot Issues

    I've finally got round to looking at these Pluses, and interestingly/unfortunately the analog boards are working fine as they boot up the logic board borrowed from a working plus just fine. Larry Pina suggests the 5v regulator or the TSM chip is to blame for logic board related flupping. I've tried replacing both of these with no success. Are there any other "usual" suspects or is it a case of checking for bad traces? Swapping ROMs and RAMs doesn't seem to help either Thanks
  6. MacinPosh

    Mac Plus Horizontal Line and Speaker Noise Boot Issues

    These are all great suggestions. I'll order up and replace parts sequentially and post my results ASAP Thanks
  7. Good afternoon all, I have acquired two Mac Plus units of which neither want to boot. I've started with the usual logic and analog board cleaning and recapping to no avail. The most promising combination of boards only achieves a white horizontal line accompanied by noise from the speaker, as seen in this video: Other combinations of board only achieve a flupping noise at various speeds with a blank screen. Nothing seems particularly broken on any of the boards, except scorching underneath the 5W 1Kohm resistor on both of the analog boards, both of which tested open and have subsequently been replaced. I know there are a lot of variables at work here and not having a working system to swap parts and narrow down the problems makes it more difficult to diagnose, but are there any specific areas that need checking/replacing to start off? Thanks
  8. MacinPosh

    Mac Plus Horizontal Sweep Lines

    Hi Everyone, I recently acquired a Mac Plus with a temperamental analog board which would only display a picture briefly whilst being tapped on the left side. I tracked this problem to a failing flyback which I have replaced, but I now get horizontal scan lines across the display which I cannot get rid of (whilst also maintaining the video brightness) by adjusting the brightness knobs. The Mac itself is otherwise working I've tried replacing R5 but to no avail. Any suggestions? Thanks
  9. MacinPosh

    SE30 Boards

  10. MacinPosh

    Mac SE - Third of screen blurry/lines on screen

    I have now replaced and adjusted a number of components as suggested, but unfortunately the foldover persists. I don't have much time to devote to this project at the moment, so i'll have to let it be until a later date. Hopefully some of the issues raised here may be useful to someone else. One thing i've noticed is that the brightness potentiometer on the front of the analog board now seems more sluggish to change brightness?
  11. MacinPosh

    Mac SE - Third of screen blurry/lines on screen

    apm - yes I did manually adjust the image centering, purely because when the brightness wasn't all the way up, you'd think the image wasn't central. Easy enough to put back. Elfen - since replacing Q2, I have tried adjusting the width to no great success, the foldover persists. I can try swapping out more parts from my donor board no problem. I haven't had much time this week to fiddle with the Mac, hopefully i'll get a chance this weekend and post the results ASAP.
  12. MacinPosh

    Mac SE - Third of screen blurry/lines on screen

    I measured the voltage at C12 and did indeed obtain a 9us long pulse. When I swapped out Q2, the foldover width reduced by half so only makes up a small proportion of the screen now. I tried turning up the brightness and the scan lines do extend off the right side, hopefully you can see it in the picture.
  13. MacinPosh

    Mac SE - Third of screen blurry/lines on screen

    Thanks Elfen and apm for the next suggestions. I'll try making those screen adjustments incrementally and see if it helps. The ferrite core does move and there is a noticeable change in the image width, but the lines just move with the picture as the width increases/decreases. I don't have a spare flyback I can try out, but I do have an analog scope to take measurements with.
  14. MacinPosh

    Mac SE - Third of screen blurry/lines on screen

    Thanks for all the replies. I've tried replacing C12 (with some caps that I accidentally ordered, but happened to be the correct value), and I've given the coils more adjustments to no avail. I'm sure that the yoke isn't the problem, as I've tested the analog board in another machine with and it still produces the lines. Is it worth me ordering a replacement flyback to see if that fixes the issue? Unless someone happens to have a spare they don't need?
  15. MacinPosh

    Mac SE - Third of screen blurry/lines on screen

    I've tried replacing the 3.9uF Cap and adjusting the width coil, but there's no improvement. It just pushes the problem left and right across the screen. Any other ideas?