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Need ground wire for Technics SL-Q300 turntable

Posted: 12 Jul 2019 14:56
by jeffv
I have resurrected my old turntable but I'm missing the ground wire, which is causing a low hum to come through the speakers. I've searched endlessly but can't seem to find the correct ground wire to purchase. Can someone tell me the correct wire I need? I ordered one on Amazon but it is too large for the porthole. Attaching a photo of the porthole.

Re: Need ground wire for Technics SL-Q300 turntable

Posted: 12 Jul 2019 15:24
by jvcforce
I have a MCS turntable that was OEMed by Technics. It also requires a detachable ground wire, but I opened it up and soldered a ground wire internally. I believe that the diameter of the ground port is exactly the same as RCA plug's center pin...
OK, I tried it, and it fits perfectly. Now, you might need to modify a cheap RCA cable, if you want to DIY.
But I think soldering a ground wire in the turntable would be better choice.

Re: Need ground wire for Technics SL-Q300 turntable

Posted: 12 Jul 2019 16:27
by jeffv
Not a bad solution. I'd prefer to just buy a replacement on Amazon or eBay but I guess I solder one on if I can't find one that fits. I'm a bit wary of opening up the case but since this component is over 30 years old, I guess I don't need to worry about voiding the warranty anymore :D

Re: Need ground wire for Technics SL-Q300 turntable

Posted: 12 Jul 2019 20:06
by lenjack
"Just" out of warranty! #-o :!: I'd butcher an rca cable, cut away the ground, connect with that, and on the other end, I'd strip away both connectors, and connect the "hot" one to the receiver/amp phono input ground.

Re: Need ground wire for Technics SL-Q300 turntable

Posted: 12 Jul 2019 22:48
by jeffv
Soldering worked but alas, I'm still getting an awful hum from the turntable and pre-amp setup. I think I might need to finally put my beloved turntable that I've had since 1984 to rest.

Re: Need ground wire for Technics SL-Q300 turntable

Posted: 12 Jul 2019 23:51
by lenjack
Let's figure out what went wrong.

Re: Need ground wire for Technics SL-Q300 turntable

Posted: 15 Jul 2019 20:11
by jvcforce
jeffv wrote:
12 Jul 2019 22:48
Soldering worked but alas, I'm still getting an awful hum from the turntable and pre-amp setup.
I think I might need to finally put my beloved turntable that I've had since 1984 to rest.
I'd check those things;

Phono cartridge connection might be loose. Check the headshell.

You might have unknowingly disconnected (pulled) existing connection. Check each connection with multimeter.

Ground wire is not soldered to the ground. Make sure a new added soldered wire is indeed soldered to ground.

Re: Need ground wire for Technics SL-Q300 turntable

Posted: 15 Jul 2019 20:17
by lenjack
In the headshell, check BOTH ends of the wires. Looks can be deceiving.

Re: Need ground wire for Technics SL-Q300 turntable

Posted: 25 Jul 2019 23:27
by Shattered