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  1. Replies
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    The Vertical Drive should have a 250 microSec...

    The Vertical Drive should have a 250 microSec negative pulse which may be to skinny for your scope to see. Check C6-pin 8 for a wider pulse with a period of 16.66 milliSec. If not there, then the...
  2. Wow, would we also be able to wifi files to the...

    Wow, would we also be able to wifi files to the new PETDisk while is connected to the PET? That would bring the PET into the 21st century.
  3. Petdisk feature wishes: Directory command,...

    Petdisk feature wishes: Directory command, support subdirectories on the SD, ability to load diskette images such as:
    Common Disk Images

    .D64 - 1541 single-sided disks for floppies 1541, 1551,...
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    568

    Yes, that counter only has one job, it counts...

    Yes, that counter only has one job, it counts horizontal scan lines and after every eight lines completes one row of characters, it outs a pulse at B1-pin8 to latch a new starting address into E8....
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    Wow the 4-State Sequencer is going crazy. It...

    Wow the 4-State Sequencer is going crazy. It should be creating the 60 Hz timing of the Vertical Sync, but is clocking so fast Vertical Sync is running at 15.6 KHz.

    There C2 NAND gate must be...
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    471

    Great work. There will probably be no need to...

    Great work.
    There will probably be no need to take the keys all apart. Just get to the bottom of the keys and clean the keypads very well with isopropyl alcohol. Be careful with the many tiny screws...
  7. Thread: PET 2001 Sound

    by dave_m
    Replies
    47
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    1,330

    No, the NAND gate is not needed. Do not use the...

    No, the NAND gate is not needed. Do not use the diagnostic signal in this speaker circuit. It may be used in the 8032 PET to disable the speaker if the Diagnostic pin is grounded, but the 2001-8 PET...
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    If you disconnect the J7 video connector, your...

    If you disconnect the J7 video connector, your monitor will be safe. With no horizontal drive signal from the mainboard connected to the video board there will be no high voltage. There appears to be...
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    Yes, remove it if you do not have or want an old...

    Yes, remove it if you do not have or want an old dot matrix printer. That is one of the worst examples of a 'Kludge' I have ever seen. It could have been done much neater using the IEEE connector as...
  10. Thread: PET 2001 Sound

    by dave_m
    Replies
    47
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    1,330

    I think so. From a PC, the line out voltage is...

    I think so. From a PC, the line out voltage is maybe around +/- 2 V into 600 Ohms (which would be 3 milli-Amp max). On the PET, the CB2 output is 0 to +5V square wave but with little drive current...
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    I finally found all the work you have done on...

    I finally found all the work you have done on this problem on the 6502 forum, I will plow through all the pages and see where you are.
  12. Replies
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    It is hard to tell the cause from the effects of...

    It is hard to tell the cause from the effects of a stuck sequencer due to the feedback terms. Please scope signals at D8- pins 4,5, and 6 to see if the counters are running. Any of the components in...
  13. Replies
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    OK, the four-state sequencer may not be running....

    OK, the four-state sequencer may not be running. Check D8-pins 4, 5, and 6 for pulses (bottom of schematic sheet 3). States are listed at the top of page 3.
  14. The Pet power transformer supplies 15VAC directly...

    The Pet power transformer supplies 15VAC directly to the video board where there is a 7812 regulator to get +12VDC. From there all other voltages in the video board are generated. A switching...
  15. Replies
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    568

    The average DC levels seem OK. The horizontal...

    The average DC levels seem OK. The horizontal sync signal is used to generate the high voltage in the CRT so that signal seems fine. When you get a scope check the Vertical drive on J7-pin 3 for a...
  16. gubbish, Put me down for one as all your...

    gubbish,
    Put me down for one as all your designs are very interesting. Is the debug port going to be some kind of serial interface?
    -Dave
  17. Replies
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    Is there a timer on that unit?

    Is there a timer on that unit?
  18. Thread: PET 2001 Sound

    by dave_m
    Replies
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    1,330

    Well yeah, but no one listens to Mike. Until it...

    Well yeah, but no one listens to Mike. Until it is too late! ;)
  19. Thread: PET 2001 Sound

    by dave_m
    Replies
    47
    Views
    1,330

    To drive an 8 Ohm speaker, you would need to...

    To drive an 8 Ohm speaker, you would need to include an amplifier chip, or but since the CB2 line goes out to pin M of the J2 User Port, you could probably use a small external amplifier/speaker...
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    Thanks for checking. It's a shame as I have the...

    Thanks for checking. It's a shame as I have the Toronto Pet Users Group library CD which has hundreds of Commodore computer programs that are packaged in .d64 image files. :(
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    ZoomFloppy still does not work with a 4040 IEEE...

    ZoomFloppy still does not work with a 4040 IEEE Drive. As I remember it did a Reset, and a Directory, but wouldn't copy a file or perform a disk image copy. I have to copy individual files using...
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    I thought they got the 8050 interface working....

    I thought they got the 8050 interface working. However I have a 4040 drive and ZoomFloppy does not work with it. It seems they put very little effort into the software debug of ZoomFloppy with the...
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    Il Paninaro, I hope you are taking good notes. ...

    Il Paninaro,
    I hope you are taking good notes.

    Our Sir Dave is turning you into a first class PET Technician. Congratulations!
  24. Yes, he mentioned something called a Pico scope...

    Yes, he mentioned something called a Pico scope that has a stated bandwidth of only 10 MHz. I don't thing he can trust it for seeing the 8 MHz clock. I hope we do not have too problems in the video...
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    Hugo, Wonderful well written technical article....

    Hugo,
    Wonderful well written technical article. Not that I could follow all of it!
    -dave_m
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