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  • #17540
    Ralph Spracklin
    CVRS Member

    SM 7000 Singing Machine completely dead. No on/off light when in ON position. Reads 117 volts to Primary of. I cannot get my meter to the contacts of the Secondary to check Voltage I am suspecting a problem with the Switch. I’ve no schematic yet. This unit was manufactured in the mid-eighties. It big and is a boat anchor

    I would like to get this working for Christmas, Everyone likes to sing at Christmas. Would like any help I and get on this one.

    Ralph

    #17551
    Doug Parker
    CVRS Member

    Ralph, post some pictures of the machine and its circuit board and I will see if I can help you get this machine singing again.

    #17553
    Ralph Spracklin
    CVRS Member

    Hello All and thanks Doug for responding, This PM I pulled the circuit board and done some pliminary checks. The power switch is working OK and the the transformer is steping down to 12.6 voltd AC. That is what I am looking for. AS this is an AC/DC set I will pick up eight “C” Batterirs and first check the set out on DC power. If the set then works, this should be telling me that the problem is in the 120 AC portion of the circuit. With the transformer doing what it was designed to do, for now I am thinking that the problem lies with a faulty 1N5401 Diode, which I will attempt to check out tomorrow. Should I not have any luck testing the diodes, and as they are cheap I will replace them all. I will keep you posted on my progress. I am also setting up my camera should I need to post some pics.

    Regards

    Ralph

    #17555
    Ralph Spracklin
    CVRS Member

    Well! After installing new batteries, and without plugging unit in to wall outlet, the ON light came on. I then thought I had diagnosed the problem correctly. I plugged in a microphone but the machine started blasting like a machine gun. Then I got to thinking that maybe the last owner, in an attempt to troubleshoot put one of the four connector plugs to the main board in the wrong place. Sure enough, I made a switch on two of the plugs, and machine gunning stopped. I picked up the microphone, and eureka, I was in business. the Karaoke Machine was working and I did not have to even test the diodes. The kids will be in their glee, and singing at Christmas. Oh my poor ears!

    Thanks for bearing with me, and listening to me squalk on this one.

    Ralph

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