Denon 300F Motor Rumble & Grounding

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edwardtuckwell
England
Posts: 1
Joined: 01 May 2019 11:45

Denon 300F Motor Rumble & Grounding

Post by edwardtuckwell » 01 May 2019 13:42

Hi all - this is a two part post all related to dreaded hum. I recently bought a B-Stock Denon 300F for a good price and have been tinkering with it to try and eliminate a couple of annoying problems. The most prevalent of which seems to be the motor hum or rumble.

I oiled the spindle with some 3in1 hoping this would solve the issue, and also flipped the grommets holding the motor in place, so there is a thicker amount of rubber between the top of the motor and the underside of the plastic chassis. And while that helped to cut some of the noise, on further inspection it seems that this sound could be coming from a vibration of the two plastic chassis pieces (top and base) in contact with each other.

Has anyone else experienced this problem and managed to find a fix ?

The other issue, quite minor is the grounding. Im getting some hum in the speakers between low and mid volume. This turntable is classed as being internally grounded. Looking at the service manual and taking the unit apart there is a 'grounding shield' in the base of the unit, which seems to be a piece of metal screwed into the plastic base with a grounding wire attached. This end is easily removable. The other end splits to two contacts attached to different parts of the internals, one near the underside of he tonearm.

Would it be worth detaching the wire from the 'grounding shield', running it out the back of the turntable and connecting it to the pre-amp ground on the amplifier? Or are there any other suggestions ?

Thought id throw these out there seeing as its not uncommon for people to be experiencing issues from this unit. Hopefully this helps someone out who is having a similar experience. Thanks for your time, cheers Ed

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