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Thread: PET 8032? dead.

  1. #1
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    Default PET 8032? dead.

    I bought a Pet 4016 and it wont power on. Draws around 32 watts from the wall when on. No beeps, no display, not even a green dot. It has a motherboard with code 8032080. Motherboard wasn't dusty and seemed in quite good condition. I have a multimeter and thats about for electrical measuring equipment. Where should I start?
    Wanted: Any old clunky 286-P1 machine that has some kind of working battery or replaceable with off the shelf parts. Preferred: 10+lbs 386 machines.

  2. #2
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    Not to sound condescending but.. Id start with the fuse.

  3. #3
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    Checked and good.
    Wanted: Any old clunky 286-P1 machine that has some kind of working battery or replaceable with off the shelf parts. Preferred: 10+lbs 386 machines.

  4. #4
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    Start with the power rails (+5V, -5V and +12V), all available at any of the RAM chips. AFAIR the 8032080 board has two 5V regulators, so check both of them.

    Schematics here:
    http://www.zimmers.net/anonftp/pub/c...niv/index.html

  5. #5
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    Checked and good. -4.9V, 12.4V, 5.1V
    Wanted: Any old clunky 286-P1 machine that has some kind of working battery or replaceable with off the shelf parts. Preferred: 10+lbs 386 machines.

  6. #6
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    Quote Originally Posted by twistedpneumatic View Post
    Checked and good. -4.9V, 12.4V, 5.1V
    You are not developing any high voltage for the screen. It may be due to no Horizontal Sync from the main board to the video board. This is caused by the CRT Controller chip (6545) not being initialized by CPU. This may be because of a ROM or RAM problem which keeps the CPU from executing properly.

    Use your voltmeter to check the Horizontal Sync signal. You can find it either at UC2-pin 1, or disconnect the video connector (J7), and check J7-pin 5. Note that the missing pin (key) is at pin 6. With the meter on DC volts, you should measure between 2.5 and 3 volts if the signal is running. This is the average of the proper duty cycle waveform.

    See sheet 10 of schematic 8032029-10. It's not the schematic for the 8032080 (newer revision) but it's good enough. Find 8032/4016 schematics at http://zimmers.net/anonftp/pub/cbm/s...032/index.html

    If you find zero or 5 Volts, the problem is on the main board. If the waveform is running, you may have a problem on your video board.

  7. #7
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    The original owner told me something like piggybacking the 3rd memory from the top or bottom(i dont remember) and it will start.

    Ill check the pin in the morning. Im pretty sure I didnt here the 15Khz tone that is quite audible on my 5151 clone anf Apple Ii monitor. Ive heard this tube is very quiet.
    Wanted: Any old clunky 286-P1 machine that has some kind of working battery or replaceable with off the shelf parts. Preferred: 10+lbs 386 machines.

  8. #8
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    Checked Pin 5 and it read 4.95V.
    Wanted: Any old clunky 286-P1 machine that has some kind of working battery or replaceable with off the shelf parts. Preferred: 10+lbs 386 machines.

  9. #9
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    It looks like you have no H. Synch.

    I would suggest trying the piggyback RAM test first then if the original owner suggested that may have worked. If you have a RAM problem - then you need to fix that first...

    Dave

  10. #10
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    Quote Originally Posted by daver2 View Post
    It looks like you have no H. Synch.

    I would suggest trying the piggyback RAM test first then if the original owner suggested that may have worked. If you have a RAM problem - then you need to fix that first...

    Dave
    Where can I obtain some 4116 RAM?
    Wanted: Any old clunky 286-P1 machine that has some kind of working battery or replaceable with off the shelf parts. Preferred: 10+lbs 386 machines.

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