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Thread: Ramsey CT-90 Counter Fault

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  1. #1
    Join Date
    Oct 2001
    Location
    Edinburgh, Scotland
    Posts
    136

    Default Ramsey CT-90 Counter Fault

    Hi all.
    Have a Ramsey CT-90 Freq Counter. Works fine on ext ps, but when fitted with int batteries, seems to work ok (not very bright display) but batteries get v hot!!
    Looks like a short somewhere in battery feed circuit, possible a cap gone leaky. Have looked for circuit diagram on internet, but so far no luck.
    Anyone out there help?

    Thanks
    Dave

  2. #2
    Join Date
    Oct 2001
    Location
    Edinburgh, Scotland
    Posts
    136

    Default

    OK, no takers. Found diagram on internet eventually, 2 hours searching!!

    73
    Dave

  3. #3
    Join Date
    May 2006
    Location
    Near Palm Springs, California
    Posts
    2,137

    Default

    Have you found the trouble?

  4. #4
    Join Date
    Mar 2001
    Location
    South West Wisconsin
    Posts
    152

    Default

    Don't feel bad my CT-50 went up in smoke yesterday.

  5. #5
    Join Date
    Oct 2001
    Location
    Edinburgh, Scotland
    Posts
    136

    Default

    "Have I found the problem".
    Not sure, is the answer.
    The manual I have now downloaded, specifically refers to using 4 x AA Nicad's, (ie 1.2v per cell) and the unit circuit shows that it will charge these, when an ext PS is connected to it.
    OK so I was trying to run the unit on 4 x AA "standard non-rechargeable" cells (ie 1.5v per cell). I did not however have the ext PS connected.
    So although the unit was working, why were these cells getting v hot? Obviously something in the circuit taking a hell of a lot of current.
    A number of diodes in circuit should have meant that the only thing taking current was on the downstream side of the bridge rectifier and 5v regulator.

    Should be a simple job to track down a possible S/C diode or similar.

    It will have to wait a couple of weeks!! I am in VE3 land at moment.

    73
    Dave

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