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Beogram 4002 won't turn off and turns itself on - Ghost inside!

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Jeffrey P Brooks
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Jeffrey P Brooks posted on Thu, Sep 23 2021 7:43 PM

I recently sold what I thought was a perfectly running Beogram 4002 to someone and they sent it back because of some mysterious behavior.

1. Sometimes, when turning off, the carriage would move all the way to the right (as it should) but it would not turn off the motor.

2. Sometime it would turn off, but after sitting for a while, the motor would just start running on its own.

I have the turntable back now and guess what?  I can't reproduce any of this.

Does anyone have an idea what might cause such an intermittent issue?  I asked the buyer to clean the contacts on the switch (the one that the carriage trips when it slides all the right), but he claimed the issue persisted.

Switch seems to work fine and has the plastic nub on it that the carriage trips.

Any suggestions as to where to look for this gremlin would be appreciated!

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Jeffrey P Brooks
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Well after a couple of hours of playing, i was able to duplicate this.  After the record finished, the tonearm returned, but the motor (and 33 RPM light) are still running.

If I unplug it and plug it in again it in it starts running again so there may be a heat component to this.

When it was in this state I moved the tonearm to the left to the point where the shutoff switch was visible.  When I manually depress it, the 33 1/3 indicator light got less bright, but the motor didn't shut off.

This is 5513 with a DC motor if that is helpful.

sonavor
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The SO switch applies a ground to the circuit it connects to in order to keep the Beogram in the "off" position.
Measure the voltage at that node (1R1 : 1D5 : 1R6) and see what it measures when the Beogram is playing and when it supposed to be off.
Off should be zero volts but it sounds like yours will not measure that.

Pressing the Start button bypasses the SO switch and causes the arm assembly to move forward, disengaging the SO switch.

Check out the voltages of all those components involved (1TR1, 1D5, 1D6, 1D7, 1D8, 1D9 and 1IC1 ) and the service manual electrical description on page 2-1 of the Type 5513 manual.

-sonavor

Jeffrey P Brooks
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Thanks Sonavor.  I have found a Beogram 4002 Type 5513 service manual, but unfortunately it does not include the picture of the PC board itself with the location of these components (and testpoints).  And sadly, it is almost impossible to read them off of the green back.

Usually, the service manuals have a fold-out page that has pictures of all the boards on it, but that seems to be missing from the online copies of this service manual.

This will be slow going!

 

sonavor
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sonavor replied on Fri, Sep 24 2021 10:27 PM

I will try to take a photo of one of my boards and highlight where the components are.

-sonavor

Jeffrey P Brooks
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Hi Sonavor,

That is okay.  I managed to completely screw up my turntable by mis-connecting some of the plugs when I put the board back.  now it is totally dead.

The service manual has a flow chart to follow for debugging, but it would be super helpful if i had a diagram of the PC board that showed where the components live.

Every other B&O service manual seems to have that, but the one that is online here does not.  I have to believe that the full service manual has the fold-out orange-colored pages that show the PC board layouts!  I guess i'll have to watch for one to come up on Ebay, unless anyone knows where I can put my hand on this image.

Jeff

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