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  1. Replies
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    yes also swapping the CIAs on the C64 could give...

    yes also swapping the CIAs on the C64 could give a clue, if something changes. But not all the C64 have socketed CIAs :)

    Frank IZ8DWF
  2. Onboard regulators can only have issues if the...

    Onboard regulators can only have issues if the electrolytic capacitors are dried out. I just suggested you to check the power supply with the oscilloscope in AC coupling (I should have been more...
  3. From what you describe (any signal at all on pin...

    From what you describe (any signal at all on pin 9 of UC7) it must be no ground connection on UC7 socket or very badly regulated power supply (200 KHz ???). That pin is an input.
    Check the UC7...
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    Ok so first of all: what kind of 1541 is it? So...

    Ok so first of all: what kind of 1541 is it? So we look at the right schematic?
    First of all, disconnect the serial cable from the 1541, power it on and check the voltage between pin2 of the serial...
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    If you have only one C64 and only one 1541, you...

    If you have only one C64 and only one 1541, you can't easily tell on what side of the serial bus lies the fault.
    To further diagnose this issue you would need at the very least a multimeter. A logic...
  6. It would be interesting to see what's actually...

    It would be interesting to see what's actually happening, if you could make a small video, it would surely help.
    As for dropping into the monitor at the start, check pin 9 (PA7) of UC7, if that's...
  7. Do you mean UI1 (not U11)? Pin 5 is driven by pin...

    Do you mean UI1 (not U11)? Pin 5 is driven by pin 11 of UH10, check page 6 of the 2001N schematic and look for VIDEO ON signal.
    Again if that signal was problematic, you wouldn't see anything on...
  8. how are the actual chips mounted on UG5 and UE11...

    how are the actual chips mounted on UG5 and UE11 marked exactly? (I'm interested if any of them is a 74LS or plain 74). Also is your probe a X1 or X10 kind? I agree with Dwight, digital sampling...
  9. hmm weird, CLK8 as far as I remember, goes only...

    hmm weird, CLK8 as far as I remember, goes only to pin 2 of UE11, it's the "dot clock" to shift out the character generator dots on each scanned row. Check the connection between these two pins. I...
  10. http://www.zimmers.net/anonftp/pub/cbm/schematics/...

    http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/2001N/320349-6.gif

    Start checking various signals referring to that schematic. 8 MHz, 1 MHz, 8 phases of CLK1, RAS0 first of all....
  11. But you don't have a blinking cursor without ...

    But you don't have a blinking cursor without 6520 in UC7, do you?
    Frank
  12. Fist thing first: R17 is the pullup for the IRQ...

    Fist thing first: R17 is the pullup for the IRQ line (all drivers must be open collector/open drain). It should give a solid high level.
    In a PET, the only drivers for IRQ are the two 6520 and the...
  13. Cursor blinking and keyboard scanning depends on...

    Cursor blinking and keyboard scanning depends on the MOS6520 in UC7 position. It should produce the IRQ with a stable period. You can try swap the two 6520 and see if things get better or worse....
  14. Replies
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    You're missing my point: to me an Apple II of any...

    You're missing my point: to me an Apple II of any kind has been always been a monochrome machine. And yes, I do know quite a bit on how PAL works (having for example fully restored a Philips PM-5508...
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    That level of complexity is what I call easy....

    That level of complexity is what I call easy. After all, I'm an electronic engineer, graduated when university was an harder place to live than today's one :)
    And well, PAL was invented precisely...
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    Hi Mattis, it seems you've already done all the...

    Hi Mattis,
    it seems you've already done all the usual checks but I'm not sure if you tested the ESR of all (even the small ones) electrolytics?. I can't help with a schematic, but I can suggest...
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    Well, of course my //c is the euro version. I...

    Well, of course my //c is the euro version. I have never seen colors out of it :) But it was free, so I don't complain.
    I could easily make a PAL adapter on the video port, but I've never really...
  18. Replies
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    I have two original SSCs with original manual :)...

    I have two original SSCs with original manual :)
    And by the way, I also have a working //c to transfer programs to floppies with ADTpro.
    In the good old days, I thought that IIe were monochrome,...
  19. Replies
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    I have found the "videoterm" 80 column schematic,...

    I have found the "videoterm" 80 column schematic, I don't know if it has a lowercase solution too.
    Any suggestion to what was the "best" or "standard" back in those days? I'm young enough to have...
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    Thanks George. I did miss the cheap compatible...

    Thanks George.
    I did miss the cheap compatible floppy controller on ebay, that will probably be the best choice.
    I thought about converting my europlus to NTSC, I'm really tempted, but I have the...
  21. Replies
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    "most useful" Apple II+ cards?

    Hi all,
    I've just completed and tested my replacement for the 16K Language Card:
    https://www.youtube.com/watch?v=1KPIAoO1dTU

    Now, what is the next most useful expansion card for a ][+ machine...
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    anyone needing a IIe 80col/64k card?

    Hi all,
    I have two 80 col/64k cards for the Apple IIe (and no IIe in sight in any near future). One card is original Apple, the other one is an italian clone (Asem). I'd swap one of them with a...
  23. Thread: My first Rev 0!

    by iz8dwf
    Replies
    29
    Views
    792

    My rev.7 had similar problems, it was an...

    My rev.7 had similar problems, it was an intermittent clock to the 6502. I think you should start checking reset action, clocks and address buffer operations. The problem in my case turned out to be...
  24. on a "FAT40" universal board, I've been luckier...

    on a "FAT40" universal board, I've been luckier with this diagnostic:
    https://drive.google.com/file/d/1bPR4ZWENU6_TbtqdkT3_W0AuK3l5Ewf7/view?usp=sharing

    It goes in the kernel position.
    YMMV
    ...
  25. Another possibility you have is to run a...

    Another possibility you have is to run a diagnostic image in place of the kernel ROM if you can burn your own 2532.
    Frank
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