Technics 1210 Groundloop and Output problem
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  1. #1
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    Default Technics 1210 Groundloop and Output problem

    Just got back into vinyl again and picked up a secondhand 1210. I've cleaned it up and everything seems to be running well, just two problems that have me stumped.

    1. I get a powerful ground loop hum when i connect and ground via my mixer, but if I connect directly to the amp and ground there it the hum becomes reasonable. I've tried grounding at amp and connecting to the mixer but it doesnt seem to improve anything.


    2. Even once connected (via phono) the turntable outputs really low volume and only the left channel. I have to gain it up all way to my amps max to even hear (with loads of hum)

    Here's some info about my set up.
    My turntable and 2 CDJs are hooked up to my mixer via fairly decent RCAs. The mixer then outputs to my amplifier and speakers. The mixer and amp are Euro devices connected via UK 3pin adapters to the power (all other devices are 3 pin UK plugs). I'm not sure whether that makes a difference but trying to include everything. I've tried powering them from the same and different sockets with no noticeable difference.

    My theory
    Problem 1 occurs because my turntable is grounding through it's chassis and not properly through the ground wire. Maybe I need to ground the turntable to the mixer and the mixer to the amp? I dont currently have long enough wires to do this. The Technics ground wire is also pretty frayed, lacking a spade and could do with replacing. Maybe grounding internally would help? Although I know many dont recommend this.

    The weird part: my mixer appears to produce a hum no matter as long as a cable is connected to either phono stage. Even if the turntable is unplugged. Could an errant cable be causing this?

    Problem 2 Normally I would say cartridge, but the AT95E i've hooked up is brand new and normally a decent choice. Could I have been unlucky? Sadly no spares around to test. Could it be the original RCAs?
    The headshell i bought is also brand new and official. Also no spares to test. I cleaned the contacts in the tonearm, didnt improve anything. Anyway of testing this without borrowing/buying something? Currently the groundloop hum increases significantly if i touch the headshell in anyway - is that normal? Never noticed it really with past decks.

    I'm not sure what to do next. Should I return the cartridge? Order new RCAs and ground wire and pull out the soldering iron? Could it be a more serious problem? I'd love to get some wisdom/insight from your experiences before I waste anymore time or money. I even looked into booking my local deck doctor but he's booked up til March. Any help would be massively appreciated.

  2. #2

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    Quote Originally Posted by AliC View Post
    The Technics ground wire is also pretty frayed, lacking a spade
    The fork? First add one and see what happens.

  3. #3
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    So interesting update:

    I tried a friends spare headshell and cartridge. All of a sudden i'm getting sound out of both channels and less hum. So i attached my cartridge to their headshell and voila, sound and less hum.

    Could it be I bought a fake Technics headshell? Looks exactly like the ones being sold on Juno and the like, but obviously its causing some problems. For reference this is the guy on ebay http://www.ebay.co.uk/itm/2822363463...%3AMEBIDX%3AIT
    So confusing.

    Next up i'l be ordering a new ground wire and RCAs to see if that completely eliminates the hum and improves sound quality a bit (which still isn't great)

  4. #4
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    Default

    You get that when something in the stylus, cart, headshell, tonearm wire connections chain isnt making a good connection.

    I'd clean all the connections and scrub all the cart contacts with a pencil eraser and a little iso alcohol on a cotton bud and reconnect everything again m8.

    And strip the ground wire back a few mm or give the frayed end a scrub to be sure of a good connection at the mixer too.
    (I dunno about the euro plugs tbh I suspect you might need to ground the TT to the amp as that's got a UK plug but that just doesn't make sense. I mean why have a ground connection on a euro mixer then? )

  5. #5
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    Good point, was gonna pick up some iso-propryl solution today just to make sure before I send the headshell back. The contacts at the back are definitely a little shorter than my friends (his looks like a black version of the mk5 headshell) so I wonder if that could be the cause, but it should work fine with my 1210mk2.

  6. #6
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    So alcohol did the trick and now the headshell is making a better connection. One problem solved.

    I think I almost have the other solved. Previously i was connecting my technics using their inbuilt cables, a female-female adaptor and some decent heavy RCA cables to make the approx 1,2m journey to the mixer. I noticed that the ground hum is there whether the deck is plugged in or not.
    So, I swapped out my thick RCA cables for some bog standard ones and voila, no more bad hum. So it was the cables? They're pretty decent solid cables, i've got the same ones coming out the back of my mixer to the amp. At first I thought it was the included ground lead they came with interfering but I pulled that out and hasnt made a difference.

    Weird one. Anyone got any clue why other than some fault in the cables?

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