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  1. Replies
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    My own 6502's NOP generator is also connecting...

    My own 6502's NOP generator is also connecting the databus directly to VCC/VSS, so far I had no issues with it. However, in case some memory is permanently selected, it would kill it. I think the...
  2. In a similar case I had, it was a marginal CR8 on...

    In a similar case I had, it was a marginal CR8 on the monitor's PCB. It might also be some intermittent solder joint on either (or both) the main PET board or the monitor board.
    In any case, it...
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    Those old AT PSUs were almost always based on the...

    Those old AT PSUs were almost always based on the TL494 pwm controller (or some clone), so not terribly difficult to troubleshoot.
    As other have already said, I wouldn't put my hands on it if I'd...
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    Hi and welcome! I think you're in EU, since your...

    Hi and welcome!
    I think you're in EU, since your VIC-20 has a PAL VIC chip.
    UNfortunately the syptoms are pointing to a bad VIC chip, the MOS6561. It could be a bad Q2 and/or associated components,...
  5. Ok, as I said, for a newly developed system, it...

    Ok, as I said, for a newly developed system, it can make sense. You don't need much of anything else, just decoding and glue logic (but I know nothing about the system you're developing).
    Here's a...
  6. The 8042 "exposes" to the system two ports,...

    The 8042 "exposes" to the system two ports, mapped at 0x60 and 0x64 on a PC. So, if you design a brand new 8 bit system, there's surely a lot to be gained by using a very well known controller. ...
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    Wrong. The 1541 works fine with a VIC-20 even...

    Wrong. The 1541 works fine with a VIC-20 even with no "UI-" command. After issuing the "UI-", the 1541 just goes faster with a VIC-20 and fails to work on a C64 unless the screen is blanked during...
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    Hi all! Sorry to sort of hijack this thread, but...

    Hi all! Sorry to sort of hijack this thread, but I do own a Profile too (and no Lisa...), so does anyone know if the Apple II's 820-5006 card to connect a Profile has a known schematic anywhere?...
  9. Thread: 8096 ?

    by iz8dwf
    Replies
    11
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    587

    It's also missing one of the TO-3 voltage...

    It's also missing one of the TO-3 voltage regulators.

    Frank
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    http://www.zimmers.net/anonftp/pub/cbm/firmware/co...

    http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/

    HTH
    Frank IZ8DWF
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    The coupling transformers and the DC/DC are part...

    The coupling transformers and the DC/DC are part of the requirement for ethernet cables to be completely floating respect the host's electronic power rails. If you notice, also the BNC connectors...
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    DC-DC converter, 12V in - 9V out, isolated (as...

    DC-DC converter, 12V in - 9V out, isolated (as far as I remember, I haven't worked with old school boards in 20 years or so).

    Frank IZ8DWF
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    It would be much better to post also the code for...

    It would be much better to post also the code for the pe3_command() function, that would help if one wants to re-use that code.

    Frank
    (I see there's a link at the original drivers, so there's no...
  14. Replies
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    1,308

    When I was a boy and I couldn't afford a proper...

    When I was a boy and I couldn't afford a proper eraser (but I could obtain a Promenade C1 programmer long enough to make a "copy" of it and use the clone on my C64), I used to erase eproms by taping...
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    Compatible TTL proms can still be found NOS. And...

    Compatible TTL proms can still be found NOS. And I have a suitable programmer for them. But well, I'm in Italy.

    Frank IZ8DWF
  16. Replies
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    I'm glad it solved the problem. Regards Frank...

    I'm glad it solved the problem.
    Regards

    Frank IZ8DWF
  17. Replies
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    Oh and by the way, yes a failing UD5 can produce...

    Oh and by the way, yes a failing UD5 can produce both a black screen and probably a "stuck" UB2's output. I've finally got the connection that I wasn't seeing at first.
    So a working UD5 should give...
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    Well Ok, Dwight already found a good reason for...

    Well Ok, Dwight already found a good reason for UD5 to be substituted (and I fully agree).

    We'll repeat some tests after you have a new 74LS107 on UD5 (again, add a socket).

    When you remove...
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    Don't pull your socket. it's probably worth...

    Don't pull your socket.
    it's probably worth pulling D5, after you test those pins on UC1
    And by the way, is D5 getting really hot as soon as you power the PET on?
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    As I said before, I've only used (and I do still...

    As I said before, I've only used (and I do still use) Hewlett-Packard probes. Unfortunately these are old and not manufactured since many years now, so it's unlikely you would find one for sale and...
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    this all look good, but: UC8 P.9 is connected to...

    this all look good, but: UC8 P.9 is connected to UE2 P.6, so try to make your probe show the same signal on both of these pins and/or check that these two pins have continuity (with the PET off)....
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    BTW, the probe isn't coping well with an 8 MHz...

    BTW, the probe isn't coping well with an 8 MHz square wave, that's what is supposed to be on 5 and 6. However since you've previously checked UD8 and UC8 that both get that 8 MHz, I'm leaning towards...
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    two ICs now: UC8 P. 5,6,8,9,10,11 UA1 P. 8,9,11

    two ICs now:
    UC8 P. 5,6,8,9,10,11
    UA1 P. 8,9,11
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    now, this isn't UE2 or you're not counting the...

    now, this isn't UE2 or you're not counting the pins correctly? I'd expect 4 to be permanently high.
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    so this would be already the second probable...

    so this would be already the second probable failed IC... hm, I'm really suspicious.
    Test UE2 P. 4,5,6 please?
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