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Thread: Atex PDP-11/34

  1. #21
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    Quote Originally Posted by Nick7928 View Post
    Hey everyone, while I was waiting for an oscillocsope, I decided to check all the voltages again to make sure that they were in spec, and while checking the -15 and +15 volt line, it showed 30 volts. Is this normal?
    Measured with respect to what reference? System GND? If you measure from -15V (on meter v-) to +15V (on meter v+) yes that would read +30V difference.

    OTOH if -15V to GND reads -30V and +15V to GND reads +30V then that is a problem.

  2. #22
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    Quote Originally Posted by Nick7928 View Post
    Hey everyone, while I was waiting for an oscillocsope, I decided to check all the voltages again to make sure that they were in spec, and while checking the -15 and +15 volt line, it showed 30 volts. Is this normal?
    Did you measure across the -15 V and +15 V lines? If so, then 30 V would be correct since there would be a 30 V potential across both. You need to measure each one individually against ground to see what they are.

  3. #23
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    Ah yes, I had completely forgot about that, I checked all the voltages and they seem in spec. What initially worried me was that the lamp on the H745 PSU went out, but it was an old incandescent light bulb which I will replace with an LED.

  4. #24
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    Quote Originally Posted by Nick7928 View Post
    No the system was in pieces when I had gotten it and I am referring to the ebay listing and common sense to get me through
    Make sure you save the pictures off the ebay listing as ebay will delete them some time after the auction is closed.

  5. #25
    Join Date
    Jan 2019
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    Hello everyone, it has been a few days since I had borrowed a 50MHz oscilloscope from my friend, and when I put it to the send line on the pdp 11 serial card, I get garbage on the oscilloscope. I may think that this is a problem with the power supply being too loud, but at the same time, I may be seeing something, but it might be going through way too fast for me.

    Thanks everyone!

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