Grounding My Turntable to my Amp Trips the house fuse

[Topstar]

HI

i just got a new second hand luxman amp LV-102 and it seems to work fine, yet when i connected it to my luxman PD-284 turntable it trips the house fuse.
i played around and i noticed that it only trips the house fuse when i connect the earth cable of the turntable.

please help!!

[Leo_Gnardo]

There must be a short within the turntable between the power line and the grounding lead. Easily verified with an ohmmeter. Is the turntable "straight from the factory" or has it been in the hands of someone who might have made a dodgy modification? The only connection the ground wire should have is to metal parts on the tonearm. I think you're going to have to examine the insides, make sure 1) no extra wires added by some errant tech, 2) AC line, motor leads, any other AC components are all well-insulated, no shorts to chassis. Some small possibility there's a short within the drive motor. Can't say I've ever seen that happen but don't rule it out.

[glebert]

When you say "house fuse" do you mean at the breaker panel or is it a GFCI outlet that is being tripped? Sometimes if GFCIs are installed incorrectly (like daisy chained) they can be really sensitive to transients. I have one that trips whenever I turn off an old Carvin tube amp, but only if the ground reversal switch is in a certain position).

[Jazz P Bass]

The amplifier is of the 2 wire mains type.

So there is not an actual 'earthed' connection.

If the turntable does not blow the breaker by itself, that leads to the amplifier being suspect.

I would measure for any voltage from the metal chassis of the amplifier to a known grounded outlet. (from chassis to the ground lug of the outlet).

[Topstar]

Thanks for the replay. It doesn't look dodgy but it is not of high quality. As it is Japanese it has had a Australian lead added. This is both for the amp and the turntable. I think i will have a look at the amp first because the turntable has never had a issue. Also i dont want to f with it as i love it. Its a beautiful piece of art in my eyes. Im in software to so i can solder but thats the limit to my knowledge.

[Topstar]

hi Jazz P Bass

i can not check the voltage as i dont have a meter, was not able to get one today.
yet i opened her up and had a look, i noticed straight away with my untrained eye that something did not look right. i have taken some photos to show you to see if you think this is suspect

in the first photo you can see the power lead coming in the solder job is ok but not very good yet we have power. but as you can see the is a blue and a brown wire, i belive there is a issue with the blue wire. the pin the wire is attached to is bent under that metal plate that goes to the voltage jumper. this plate the voltage jumper is attached to is mounted to the frame, (untrained again) meaning there is power running throung the main frame of the amp. as you said there is no actual earth connection, i thought is was not right start away.
any advice from this point would be great, i dont want to do more damage to the amp, as everthing but the hum is perfecto.

photo 1 above view of the amp, showing the brown and blue wires from the power lead. connection on blue wire poor in my eyes and will probery reconneted it mayself.


Photo 2 Showing the side view of the pin the blue power wire is attached too, notice how it is bent under the metal insert the voltage jumper is attched too. (i belive this is maybe a sheld)


Photo 3 show in the metal insert that the voltage jumper is attached too, this is mounted with two screws to the main metal frame of the amp.

[Topstar]

Thanks Jazz P Bass, i belive i have found the issue what do you think

Thanks Jazz P Bass

i have attached three photos showing how the power is connected and it look suspect to me.

photo 1 show the above view of the power lead coming in, there is a brown and a blue wire. the pin attached to the blue wire is bent under the inserted metal of the voltage jumpers. this pin is touching the metal insert and the insert is mounted directly to the main chassis of the amp. maybe when i attach the ground from the turntable this then is shorting the house breaker. as a dangerous circuit is created.



Photo 2 a side view showing the pin bend under the metal insert, notice the pin is connected to the insert



Photo 3 Top view showing the metal insert with the voltage jumper and how it is attached to the main chassis



Jazz or anyone do you think this suspect and could be the course to the hum from the amp, accross all input channels (phone , cd, av 1 etc)

thanks again for your response and everyone elses.

[Topstar]

Thanks Jazz P Bass

i have attached three photos showing how the power is connected and it look suspect to me.

photo 1 show the above view of the power lead coming in, there is a brown and a blue wire. the pin attached to the blue wire is bent under the inserted metal of the voltage jumpers. this pin is touching the metal insert and the insert is mounted directly to the main chassis of the amp. maybe when i attach the ground from the turntable this then is shorting the house breaker. as a dangerous circuit is created.

Photo 1 top view showing power lead coming in and connection to pin

Photo 2 side view showing the pin from the blue wire bent and touching metal insert

Photo 3 top view showing metal inset of voltage jumper connected to the main chassis

[Dave H]

photo 1 show the above view of the power lead coming in, there is a brown and a blue wire. the pin attached to the blue wire is bent under the inserted metal of the voltage jumpers. this pin is touching the metal insert and the insert is mounted directly to the main chassis of the amp. maybe when i attach the ground from the turntable this then is shorting the house breaker. as a dangerous circuit is created.

That looks horrendous! It can't be right. There should be a big clearance distance between the mains pins and the metalwork.

[Leo_Gnardo]

Thanks Jazz P Bass

i have attached three photos showing how the power is connected and it look suspect to me.

photo 1 show the above view of the power lead coming in, there is a brown and a blue wire. the pin attached to the blue wire is bent under the inserted metal of the voltage jumpers. this pin is touching the metal insert and the insert is mounted directly to the main chassis of the amp. maybe when i attach the ground from the turntable this then is shorting the house breaker. as a dangerous circuit is created.

Photo 1 top view showing power lead coming in and connection to pin

Photo 2 side view showing the pin from the blue wire bent and touching metal insert

Holey crow, that's it right there! Somehow I knew peering inside the turntable base would reveal a problem. You could snip away the upper part of the post that's shorting mains to the turntable chassis, I'm sure your breaker popping problems will cease after that. Also I'm sure Jazz will sound off about this soon as he wakes up - it's Sunday morning in North America where we are. Meanwhile consider yourself lucky. This kind of fault could have resulted in a fatal shock or an unintended welding session between your hi fi gear and anything that's grounded. Hum in the audio? The least of your problems. Snip, reassemble, play, enjoy. I wonder how many other of these turntables are out there waiting to cause their owners/operators consternation or worse.