Beogram 8000 Speed Issues

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Home Forums Product Discussion & Questions BeoGram Beogram 8000 Speed Issues

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  • #48672
    UsefulIdiot
    BRONZE Member
      • Topics Started 3
      • Total Posts 3

      Hello! I’m having some trouble with a Beogram 8000 and I’m hoping someone here can provide some guidance. At first, it spun way too fast. Luckily, these forums pointed me towards replacing the tacho disc. It worked great and the speed was perfect!

      Then I started having trouble with the tonearm randomly moving all the way over to the right. Whenever it acted up, the controls would stop working as well. So, I did some more reading in these forums, replaced all of the electrolytic capacitors, and reflowed a bunch of questionable solder joints. Again, it worked! The tonearm now moves just as you would expect it to.

      However, then the platter spun way too fast again. Near top speed, if I had to guess. I studied the schematic as best as I could and started checking power supply voltages. They were a few volts off here and there, but I had been using a dim bulb setup for safety, so it was hard to tell if there was an actual fault. Current draw was fairly low, so I decided to take the dim bulb setup out of the equation. Unfortunately, after about 30 seconds, it blew the 300mA fuse inside the transformer box

      The good news is that I realized that I had missed the capacitor hiding in there. This one differed a bit from the schematic I have though. The schematic says it should be a 39uF bipolar, but I found a 27uF bipolar instead. I didn’t have the correct value on hand, so I decided to try a pair of polarized 22uF capacitors with the ground pins soldered together. I tested it with the dim bulb setup again and the speed is much closer, but still about 13rpm over what it should be.

      I did notice that the platter doesn’t stop moving after the motor shuts off. I’ve done a little reading on it and it sounds like there’s a braking circuit that briefly reverses the polarization of the motor. I think the bipolar capacitor is part of that circuit? It does connect directly to coil 0L1. How critical is the capacitance of the bipolar cap when it comes to platter speed? Does it affect it at all? Should I go with another 27uF, or use a 39uF like the schematic shows? I have a lot more technical questions, but I’ll leave it at that for now.

      #48673
      spassmaker
      BRONZE Member
        • Topics Started 12
        • Total Posts 115

        Hi

        As far I can remember is that when you put 2 caps in a row you have to double the capacitance.

        I would try two 47uF in row.    +–+

        The brake circurit has to be checked too.

        Check TR21 TR32 TR33 and the value and polarity of C 43

        Let us know if you got any progress

        Kind regards

        Christian

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