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  1. Replies
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    Or just use a low current form A reed relay in a...

    Or just use a low current form A reed relay in a DIL package and drive that from the +5 V rail or a separate output from the Arduino.

    If you used two relays on an output bit from the Arduino, you...
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    After that pesky PET the Law of averages has to...

    After that pesky PET the Law of averages has to give you a simple fault :-)!

    What’s next to repair (he says being cocky!).

    Dave
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    So, the Z80 appears to be executing :-)... ...

    So, the Z80 appears to be executing :-)...

    When you say "the LED doesn't light", which LED do you mean? There is a power LED and a CAPS LED. The power LED should illuminate (it comes directly off...
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    The +12V rail looks a little high - but we found...

    The +12V rail looks a little high - but we found that with the PET when we measured stuff didn't we?

    Logic probe time on the Z80 CPU (U3)... Let me know whether the pin(s) are high, low or...
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    Hi Roland, I am at work at the moment and I...

    Hi Roland,

    I am at work at the moment and I have just done a web search and can't find the manual I was using. I will check my browser history when I get home and post the link to what I found.
    ...
  6. Thread: Mindset repair

    by daver2
    Replies
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    746

    Don’t forget that pressing ALT SYS CONFIG (or...

    Don’t forget that pressing ALT SYS CONFIG (or some other key combination) enters the SETUP/CONFIG screen. This may stop the normal boot up execution of the BIOS.

    Dave
  7. Replies
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    Assuming I am reading the correct manual (which...

    Assuming I am reading the correct manual (which is not guaranteed at this time of night in the UK!), error 32 means "Main Board ROM CRC ROM 2".

    That's my guess before I turn in for the night at...
  8. Thread: Mindset repair

    by daver2
    Replies
    54
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    746

    If you look at the two pictures (cpu_b.jpg and...

    If you look at the two pictures (cpu_b.jpg and cpu_t.jpg) here http://bitsavers.org/pdf/mindset/pictures/pcb/ you will see that the green wire snakes through the via to pin 3 of the nearest 8042 to...
  9. Thread: Mindset repair

    by daver2
    Replies
    54
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    746

    Just been looking at the pictures of the main...

    Just been looking at the pictures of the main PCB.

    That's interesting if you have one crystal and two 8042 micro controllers. I wonder if one is connected to the crystal and this one (in turn)...
  10. Thread: Mindset repair

    by daver2
    Replies
    54
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    746

    >>> My read of the video production system manual...

    >>> My read of the video production system manual suggested that you should test out the machine without anything connected, which implied to me it didn't matter.

    Agreed now I have re-read the...
  11. I'll have a look. It will have to be next weekend...

    I'll have a look. It will have to be next weekend now (I will be on a business trip shortly)...

    Fortunately, I have the complete documentation pack that came from DEC for my machine :-).

    Dave
  12. Replies
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    It's a computer with a power supply and a...

    It's a computer with a power supply and a microprocessor.

    Once you can fix one...

    Dave
  13. Thread: Mindset repair

    by daver2
    Replies
    54
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    746

    When you say 'video production' module, do you...

    When you say 'video production' module, do you have the external unit with the fader or not?

    I see an 'external synchronisation' cable that must be fitted between the two units etc.

    Dave
  14. Thread: Mindset repair

    by daver2
    Replies
    54
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    746

    With the power switched OFF you should be able to...

    With the power switched OFF you should be able to trace the wiring with your multimeter set to read Ohms.

    Pin 2 of the 8042 should only be connected to one side of the 12 MHz crystal.

    Pin 3 of...
  15. Thread: Mindset repair

    by daver2
    Replies
    54
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    746

    So, the 8042 microcontroller can be clocked in...

    So, the 8042 microcontroller can be clocked in one of two ways:

    1. Pin 2 is connected to 0V/GND. In which case an external clock is fed into pin 3.
    2. A crystal is connected between pins 2 and 3....
  16. Thread: Mindset repair

    by daver2
    Replies
    54
    Views
    746

    Do we have a manual or a schematic anywhere you...

    Do we have a manual or a schematic anywhere you are aware of by any chance?

    Sorry, brain fade, bitsavers - duhhhhh!

    Dave
  17. Just checked my 11/45 backplane and (you are 100%...

    Just checked my 11/45 backplane and (you are 100% correct) the SPC slots only have the BG/BR wired and not the NPR/NPG.

    Thanks for the 'heads-up' Joerg.

    A little bit of wire wrapping therefore...
  18. Thread: Mindset repair

    by daver2
    Replies
    54
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    746

    >>> My god.. what is in those things! WMD... ...

    >>> My god.. what is in those things!

    WMD...

    >>> I would have thought interlacing would be mentioned in the documentation or brochure somewhere..

    It may be more to do with the modification...
  19. Ah ha! The VIDEO ON signal (generates the...

    Ah ha!

    The VIDEO ON signal (generates the interrupt for the cursor flashing) and the VERTICAL DRIVE signal come from the same flip-flop logic on schematic page 6. It is, therefore, something...
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    Me again!!! Schematics (and technical manual)...

    Me again!!!

    Schematics (and technical manual) over at http://www.zxprojects.com/images/stories/philipsvg802000sm.pdf (assuming this is the same machine as you have of course).

    Same rules apply...
  21. Thread: Mindset repair

    by daver2
    Replies
    54
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    746

    If you have a composite signal out, can you get...

    If you have a composite signal out, can you get an oscilloscope trace of a few lines of the video signal and a complete frame so we can see what is going on.

    Just thinking interlaced video signal...
  22. I am not stating that the PET uses an interlaced...

    I am not stating that the PET uses an interlaced scan. I am thinking that the vertical drive signal is getting displaced in time based upon alternate frames.

    The logic for the vertical drive...
  23. Thanks for the info guys. Dave

    Thanks for the info guys.

    Dave
  24. That is a weird one... The fact that you...

    That is a weird one...

    The fact that you appear to have two separate images on the screen implies to me that it is odd/even frame related - otherwise you would have one image only that is...
  25. Hi Joerg, Nice job. I have an 11/45 I am...

    Hi Joerg,

    Nice job.

    I have an 11/45 I am resurrecting. It has the CPU and FPU but no memory cards or I/O devices. I do have some spare SPC slots in the UNIBUS backplane, so this looks like the...
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