Arm wire interference

graeme uk · 21st January 2007, 06:36 PM

I just rewired my arm with satcure titz, enameled strand, silk wrapped.

I now have a bad hum though. The wire replaced magnet wire.

All 4 wires are threaded through the arm, then there bare for about 7 inch (needed for arm movement) then there sandwiched between two layers of packing tape right down to the phono's.

The magnet wire was exactly the same except they were taped to the outside of the arm.

What could be making it hum now, but not before?

The new wiring is about 50cm longer than before, but i doubt that matters.

Any suggestions for what may be causing it? If i touch the wires the hum changes.

Apart from that, the satcure litz sound very nice

livemusic · 21st January 2007, 06:44 PM

Have you twisted each pair of wires for every channel?
Like this:

graeme uk · 21st January 2007, 06:47 PM

no, but ill give it a go and see if it cures it.

The old wiring wasnt twisted either though and that had no problems.

Im wondering if the enamel and silk is enough to shield the wires from each other where they run together inside the arm?

graeme uk · 21st January 2007, 08:30 PM

I tried twisting but it made no difference, the hum gets louder when i touch the exposed sections.

tade · 21st January 2007, 08:37 PM

electrically the shielding ought to be fine. electromagnetically no, but neither would any insulating coating.
if the arm is made of metal that will add shielding. also, check and make sure your connections are good ie look for dirty contacts of dry solder joints. none of the wires are shorted to anything else are they?

bulgin · 21st January 2007, 10:11 PM

Hi

Like tade said, I'm almost 100% sure a wire is touching (shorting) where it shouldn't.

Use a multimeter set on 'continuity' and check between the wires and the arms metal parts, or between channels.

bulgin

graeme uk · 22nd January 2007, 08:42 AM

I stripped all the wiring out and i think they were touching. Where i'd pulled them through the arm the silk had snagged and pulled away.
I will also check the connections though.

Thanx folks.

tade · 22nd January 2007, 12:57 PM

if the wires which connect to the outer, ground part of an rca plug are not well connected noise is assured. One of the first audio projects i did was to make a simple volume control by splicing in a potentiometer. First of all i didn't use a resistor divider network so it wouldn't have worked as a passive volume adjustment, but more to the point i installed the pot on the outer sleeve so basically i was turning the shielding up and down. I had a cable with controllable noise! : )

hacknet · 22nd January 2007, 02:42 PM

i had the same problem. ended up being a cold solder on the RCA plug.

graeme uk · 23rd January 2007, 09:20 AM

well, i rewired it. Theres definately no short between wires. The arm is fiberglass.

Silly quetion, but how cn i use my multimeter to check the solder joints? They look fine.

You may have guessed it still hums, and picks up radio

21st January 2007, 06:36 PM	#1
graeme uk diyAudio Member Join Date: Dec 2005 Location: essex	arm wire interferance I just rewired my arm with satcure titz, enameled strand, silk wrapped. I now have a bad hum though. The wire replaced magnet wire. All 4 wires are threaded through the arm, then there bare for about 7 inch (needed for arm movement) then there sandwiched between two layers of packing tape right down to the phono's. The magnet wire was exactly the same except they were taped to the outside of the arm. What could be making it hum now, but not before? The new wiring is about 50cm longer than before, but i doubt that matters. Any suggestions for what may be causing it? If i touch the wires the hum changes. Apart from that, the satcure litz sound very nice

21st January 2007, 10:11 PM	#6
bulgin diyAudio Member Join Date: May 2006	Arm Wire Interference Hi Like tade said, I'm almost 100% sure a wire is touching (shorting) where it shouldn't. Use a multimeter set on 'continuity' and check between the wires and the arms metal parts, or between channels. bulgin

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21st January 2007, 06:47 PM	#3
graeme uk diyAudio Member Join Date: Dec 2005 Location: essex	no, but ill give it a go and see if it cures it. The old wiring wasnt twisted either though and that had no problems. Im wondering if the enamel and silk is enough to shield the wires from each other where they run together inside the arm?

21st January 2007, 08:30 PM	#4
graeme uk diyAudio Member Join Date: Dec 2005 Location: essex	I tried twisting but it made no difference, the hum gets louder when i touch the exposed sections.

21st January 2007, 08:37 PM	#5
tade diyAudio Member Join Date: Feb 2005 Location: Ralieigh nc	electrically the shielding ought to be fine. electromagnetically no, but neither would any insulating coating. if the arm is made of metal that will add shielding. also, check and make sure your connections are good ie look for dirty contacts of dry solder joints. none of the wires are shorted to anything else are they?

22nd January 2007, 08:42 AM	#7
graeme uk diyAudio Member Join Date: Dec 2005 Location: essex	I stripped all the wiring out and i think they were touching. Where i'd pulled them through the arm the silk had snagged and pulled away. I will also check the connections though. Thanx folks.

22nd January 2007, 12:57 PM	#8
tade diyAudio Member Join Date: Feb 2005 Location: Ralieigh nc	if the wires which connect to the outer, ground part of an rca plug are not well connected noise is assured. One of the first audio projects i did was to make a simple volume control by splicing in a potentiometer. First of all i didn't use a resistor divider network so it wouldn't have worked as a passive volume adjustment, but more to the point i installed the pot on the outer sleeve so basically i was turning the shielding up and down. I had a cable with controllable noise! : )

22nd January 2007, 02:42 PM	#9
hacknet diyAudio Member Join Date: Nov 2002 Location: sg	i had the same problem. ended up being a cold solder on the RCA plug.

23rd January 2007, 09:20 AM	#10
graeme uk diyAudio Member Join Date: Dec 2005 Location: essex	well, i rewired it. Theres definately no short between wires. The arm is fiberglass. Silly quetion, but how cn i use my multimeter to check the solder joints? They look fine. You may have guessed it still hums, and picks up radio

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