Image Map Image Map
Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 36

Thread: First Apple 2e in 20 years! Vertical bars on boot

  1. #21
    Join Date
    Jan 2014
    Location
    Melbourne, Australia
    Posts
    549

    Default

    No luck. I've replaced the crystal, and every logic IC, and the RAM, and the CPU. Still weird block patterns and corruption.

    I've ordered some ROM's from modem7 - let's try that :/
    Bobby.

  2. #22
    Join Date
    Jan 2014
    Location
    Melbourne, Australia
    Posts
    549

    Default

    Ok guys got an update...

    Still not working!!

    I've replaced the CD, EF and Video ROM's (thanks modem7) as well as the RAM and tried replacing every LSxxx chip

    Volts are good, CPU Pin 7 has a clock, Reset pin goes low-high on boot and stays high.

    What on earth else could be wrong?

    thumbnail_IMG_9855.jpg
    Bobby.

  3. #23
    Join Date
    Jan 2014
    Location
    Freedom City
    Posts
    6,380
    Blog Entries
    2

    Default

    Is there an easy way to check MMU? I don't recall.. Maybe by pulling the 6502, you can force addresses and see what it does.

  4. #24
    Join Date
    Jan 2014
    Location
    Melbourne, Australia
    Posts
    549

    Default

    I wouldn't know how... I have a logic probe finally. Anyone know how to do this?

    If it's bad, where would I get another MMU?

    Another update: Does this look like it's actually running something (like the self test)? It isn't legible, but seems to be doing 'something'... is this a clue?

    http://www.youtube.com/watch?v=K_kglXf3R7I

    Edit: I'm still confused as to why the Power LED doesn't light up. Is this software controlled?
    Bobby.

  5. #25
    Join Date
    Dec 2016
    Location
    New Jersey
    Posts
    148

    Default

    I think you said you have already tested your power supply, but all signs are pointing to it right now. You may have disconnected the speaker for the beeper but that might help you troubleshoot as well.

    https://www.applefritter.com/files/A...r_SAMS1985.pdf

    https://archive.org/details/Apple_Se...-0229/page/n41

  6. #26

    Default

    Earlier you mentioned you were using a bench supply to power it. What sort of bench supply are you using to power the unit?

    The factory supply has +12 +5 -5 -12 rails. Are you 100% sure you have the correct voltages on all of them? If your not using a quad channel supply (i.e. using more than one supply) be very careful with your ground reference. They all need to be interconnected correctly; and some supplies don't play nicely together.

    The power led is not software controlled. This points to one of your voltages being missing. I *think* it is powered by the +12 rail; although last time I checked was years ago so I could be wrong. I just have this recollection that it wasn't powered by the +5v rail...

    Also check the voltages on the little axial capacitors just adjacent to the power connector on the motherboard. It's possible you have a corroded pin or broken trace in/around the power header itself.
    Last edited by 3pcedev; December 7th, 2018 at 03:09 PM.
    System 80 Expansion Interface located! Thanks to all who helped out and the good people in the NZ vintage computer forums!

  7. #27

    Default

    Also are you checking the voltages with the PSU hooked up to the motherboard?

    It's unlikely but not unheard of to have shorted capacitors on IIE motherboards. One of the voltage rails may be shorting out and causing the PSU to go into protection mode.
    System 80 Expansion Interface located! Thanks to all who helped out and the good people in the NZ vintage computer forums!

  8. #28
    Join Date
    Jan 2014
    Location
    Melbourne, Australia
    Posts
    549

    Default

    Hey guys,

    I’ve actually fixed the 2e supply, and I’ve been tryinf with both my quad channel bench supply and the 2e one.

    All voltages seem fine when it’s connected to the board. And those caps near the power plug are ok... still weird that the LED won’t light up!
    Bobby.

  9. #29

    Default

    I vaguely remember the LED being triggered through some sort of 74S logic. You mentioned you replaced some 74LS chips; however the fault may be with one of the 74S ones.

    Here's a troubleshooting guide that mentions some 74S logic that should be checked when the power light is not functioning (scroll down to about 1/2 way): http://www.1000bit.it/support/manual...r2e/repair.htm

    Note that you have a PAL IIE - IIRC the ID of the chips is the same (at least everything thats not video related) however the physical location differs. The troubleshooting guide should still be relevant.
    System 80 Expansion Interface located! Thanks to all who helped out and the good people in the NZ vintage computer forums!

  10. #30

    Default

    Ignore my comment above - According to the schematic linked here the power LED is definitely DIRECTLY off the 12V rail.

    Try probing the +12V somewhere else on the board. There are a couple of places - one is pin 50 on the expansion slots and another is the clock generator (see link here)

    My guess is that the +12 isn't making it to the clock generator......
    System 80 Expansion Interface located! Thanks to all who helped out and the good people in the NZ vintage computer forums!

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •