Posts: 1171
From: Highland Mills, NY USA
Registered: Jun 2003
posted January 11, 2018 04:49 PM
I have a Sony PSLX-250H non-usb belt driven t/t connected to a phono amp (turned off the turntable’s built in pre amp) and then connected a pair of Harmon Kardon pc speakers. Now I have no issues with the clarity or the volume, but I can’t seem to eliminate a hum that can be heard even when nothing is playing. I get the hum whether I use an external phono amp or the unit’s built in pre amp. The t/t does NOT have a ground wire to connect so it all must be self-contained. Hooked the t/t to my daughter’s boom box and the hum was there so it’s definitely eminating from the t/t. Thoughts....? Could it just be the way the $99 t/t was built?
posted January 11, 2018 06:48 PM
If there's no ground wire, I'd venture that something's missing. I've never heard of a cartridge without one. And without one, every one I've ever used hums loudly. Good luck, Brad.
Posts: 1171
From: Highland Mills, NY USA
Registered: Jun 2003
posted January 11, 2018 06:59 PM
The cartridge is all intact. The rca wires I use I connected to other elements and no hum. The t/t manual specifies that the unit is grounded internally plus there’s no slot in the back to insert one if I wanted to.
posted January 12, 2018 04:08 AM
Ive had hum when the push on connectors for the wire at the cartridge end have been a little loose or badly connected try touching the insulation around them when the amp is on and see if the hum decreases or increases. If it does there is a bad connection there and they may need tightening or cleaning.
Posts: 1006
From: West Midlands United Kingdom
Registered: Aug 2011
posted January 13, 2018 08:04 AM
Hi Brad, had a similar problem with technics sl 1200 and this does have a grounding cable, if the head shell screws off the arm, check the connection pins in the arm as these can get crud on them and the tiny electrical contact between the two is compromised, I used a tiny piece of emery paper on a match stick and cleaned each one, fixed the humming and did not return.
Posts: 1171
From: Highland Mills, NY USA
Registered: Jun 2003
posted January 14, 2018 05:06 PM
The cartridge is permanent and not removable. Only the stylus is removable. When I place my finger on the ground screw on the back of my phono amp the hum disappears. The t/t definitely does not have a ground cable nor anywhere to connect one. I don’t want to dis-assemble the t/t because that could result in more problems than I want. Not being electrically skilled I could see myself getting into a pile of poo.
Posts: 873
From: Southern England
Registered: Apr 2008
posted January 15, 2018 06:54 AM
Turntables need grounding or there will be a hum. You say you are using a separate phono amp but is that grounded? When you touch the grounding terminal you are yourself making the ground so there is the proof it needs it. A hi fi amplifier with a phono input will have a grounding screw and that is for the turntable.