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HP 1740A Help

Discussion in 'General Electronics Chat' started by PigHeaded, Mar 7, 2006.

  1. PigHeaded

    PigHeaded New Member

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    I have a HP1740A Oscilloscope that does not display a signal. I took the cover off and I do not have a glow in the CRT. Before I spend money on a replacement CRT I would like to know if that is the problem. There are several wires that connect to the back, the top and the side of the CRT, but I do not have a service manual to tell me what they should read. Does anyone here know? I will be getting a service manual, but I wanted to order a CRT at the same time, if it is the problem.

    Thanks,

    Sean
     
  2. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    I would have thought it's EXTREMELY unlikely to be the CRT, more likely the power supply is faulty!. It's a very trival job to check the CRT for such a potential fault - it can only be caused by the CRT heater being O/C - which you can test with an ohm-meter.

    I also expect you would be astonished at how expensive a replacement CRT would be!.
     
  3. PigHeaded

    PigHeaded New Member

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    Thanks for the quick response. Do you know which lines are for the heater? I have not been able to find a pin layout for the CRT online.

    Thanks,

    Sean
     
  4. dave

    Dave New Member

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  5. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Sorry, but I've no idea - but it should be fairly easy to work it out, for a start they will be the only two that read a low resistance.
     
  6. PigHeaded

    PigHeaded New Member

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    Thanks again. I Will run through the pins.

    Sean
     
  7. ljcox

    ljcox Well-Known Member

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    I have a 1740A and a Service Manual. But I am not at home at the moment.

    In what country do you reside?
     
  8. PigHeaded

    PigHeaded New Member

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    Hello ljcox,

    I live in the united states. I would love to get a copy of the service manual!

    Also note that I checked out the pins and found that the heater is receiving 6.3 volts. I than pulled the connector off the crt and found that the heater pins are open. So the crt is bad. Now I have to find a cheap crt. Thanks for helping me find this information out.

    Sean
     
  9. ljcox

    ljcox Well-Known Member

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    Sean,
    I sent you a PM yesterday, did you receive it?
     
  10. zevon8

    zevon8 New Member

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    Toronto, Canada, eh

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