Beogram 4000 record detection issue

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  • #6726
    alf
    BRONZE Member
    • Topics Started 7
    • Total Posts 23

    Hi All,

    working on my BG4000 which does have record detection issues:

    first the detector arm bulb dies not come on ?
    It measures about 40 ohm and is getting 6.3V supply when ON is actuvated.

    checking the collector voltage at 1TR14 I should see a max of 2.2V  – the max I see is

    1.6V.
    Both, 1TR14 and 1C9 have been tested off board as good ??

    what am I missing here and why isn’t the bulb illuminated ??

    help would greatly be appreciated 🤗🤗

    ALF

    #6727
    spassmaker
    BRONZE Member
    • Topics Started 3
    • Total Posts 31

    Hi Alf

    As the bulb is measuring about 40 Ohm it should be OK.

    Check 1 R 30 (15 OHM) and all tracing connections.

    About Transistors which are measuring off board in a good state….

    If I pull one of these little BC5XX Transistors out I always put a new one in, cost only 5 to 20 cent and you’re shure that the new one will work.

    Had already a lot of them measuring good, but a HFE about 20 or 100, too low in that case.

    Hope it will help a little bit.

    Kind regards

    Christian

    #6729
    alf
    BRONZE Member
    • Topics Started 7
    • Total Posts 23

    Hi Christian,

    thanks for the input, very much appreciated.

    R30 measured 14.9 ohm !

    i revisited that detector bulb, definitely not lighting up, so I put a “replacement” that lit up straight away as expected when 6.3V are present.

    However that “replacement” is not the correct bulb – my hope is Martin (Dillen) can supply a correct one ?!

    ALF

    #6739
    hcraig244
    BRONZE Member
    • Topics Started 3
    • Total Posts 72

    Alf

    Does the record detection circuit work with the replacement bulb….or are there still issues?

    Craig

    #6742
    alf
    BRONZE Member
    • Topics Started 7
    • Total Posts 23

    Hi Craig,

    it worked before the original bulb went dead.

    The “replacement bulb” has a different filament type – it lights up but does not produce

    the correct light circle.p through the lense.

    the correct bulb has been ordered from Beoparts shop yesterday – now its the waiting game until it arrives.

    ALF

     

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