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LOUD turntable hum only after time elapse

Jon408

Jon408

New Member
I have a Beogram RX that hums only after I've been playing records for a period of time, and the hum can even start when the turntable has stopped (but it never starts unless the turntable was turning). It is quite loud. I have changed amps and speakers to isolate the problem, and it must be the turntable. The turntable is grounded to the amp, but when I disconnect the ground there is a different hum - which goes away as soon as I reconnect the ground wire.

It's as if there is something inside the turntable that is slowly building up a charge in close proximity to a cable or something else... and when the charge becomes great enough, it goes to the amp and through to the speakers.

Equipment:
Beogram RX
Sansui AU 9900
JBL L55s
 
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My Thorens TD 147 does the exact same thing!! When I first start listening to an LP it's absolutely silent and then after playing for 10 minutes or so, the hum begins and gets louder and louder. I have my ground attached to my Sony RTR and had no problem for a while. Very weird!! I have a McIntosh 2105 amp and C28 preamp. Speakers are JBL L200s and Klipsch Reference speakers. Cheers!!
 
Jon408 said:
I have a Beogram RX that hums only after I've been playing records for a period of time, and the hum can even start when the turntable has stopped (but it never starts unless the turntable was turning). It is quite loud. I have changed amps and speakers to isolate the problem, and it must be the turntable. The turntable is grounded to the amp, but when I disconnect the ground there is a different hum - which goes away as soon as I reconnect the ground wire.

It's as if there is something inside the turntable that is slowly building up a charge in close proximity to a cable or something else... and when the charge becomes great enough, it goes to the amp and through to the speakers.

Equipment:
Beogram RX
Sansui AU 9900
JBL L55s
Click to expand...

More likely that heat is building up and a component changes as it gets warm. Quite often a dry or cracked solder joint on a circuit board will be fine until the whole thing has warmed up enough for the board to flex by a couple of microns and the joint goes open circuit. The fault mysteriously disappears when starting again from cold.
 
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