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Turntable Hum , RCA cables

buckeye56

buckeye56

Active Member
Using newly repaired turntable. Left channel on my Technics SA 205 receiver works for a while, then cuts out. Sometimes I can hear static like sound from the left speaker. The red/white RCA cables, I swapped one pair for another. if I move them in a particular way, a loud hum is emitted from one of the channels.

I cleaned my receiver (Deoxit) so what could be the possible issue here? I don't play things loud. Are all red/white RCA cables the same? No issues when listening to radio, CDs or music via my iPad and the 3.44mm cable connected to my receiver.

Thanks
 
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It sounds like you have a bad connection somewhere in the common side...carried by rhe outer ring of your rca plug and jack. The problem could be a break in the wire right inside the insulation at the base of the plug (very common in old thin rca phono cables), corrosion on the outside of the jack, loose solder connection to the common side of the jack inside your receiver. My Hafler DH110 preamp had that problem every couple years....very nice inexpensive pre, but awful jack design.
 
would agree with @mythless . You also may want to check for broken solder connections where the phono RCA jacks are soldered to the board, or cold or cracked solder joints in the phono stage itself.
 
mcgjohn said:
would agree with @mythless . You also may want to check for broken solder connections where the phono RCA jacks are soldered to the board, or cold or cracked solder joints in the phono stage itself.
Click to expand...
What would that even look like to the naked eye? I have zero skills in that area, how to fix, etc.
 
buckeye56 said:
What would that even look like to the naked eye? I have zero skills in that area, how to fix, etc.
Click to expand...
You mentioned that if you moved the cables one way or another, you could induce a loud hum. What is probably happening as you do that is that the motion of the cable is breaking the connection to ground (the ring part of the RCA plug/jack, not the center pin).

You mentioned that you've tried swapping out the cables. Just for sanity's sake... try it again. If you can get the hum to stop and good sound by gently wiggling the plug in the jack, once you've got good sound, hold the plug still and gently wiggle the cable just behind the plug. If that causes the hum to return or the sound to stop, you've found the problem and it's the cable.

If that doesn't do it, and wiggling the plug itself causes the hum or the signal to make/break, then the problem is most likely in the jack or an internal solder joint. Start by carefully crimping the outer ring of the plug just a tiny bit so it grips the jack better. If that doesn't do it....

UNPLUG your receiver. Remove the cover to gain access to the guts. Be careful around big can-shaped capacitors... they will still have bunch of juice in them and can give you a nasty shock if you touch the contacts. Find the input jack(s) in question along the back of the receiver from the inside. VERY gently wiggle the suspect one and see if you can see a leg or solder joint move. If you do, you've found the problem. Resolder the joint and you should be good to go.
 
buckeye56 said:
What would that even look like to the naked eye? I have zero skills in that area, how to fix, etc.
Click to expand...

If you have a magnifying glass, look at each solder joint where an RCA connector is attached. if it looks rough, has small micro cracks, or other visual defects, it may be a cracked joint.
 
buckeye56 said:
Using newly repaired turntable. Left channel on my Technics SA 205 receiver works for a while, then cuts out. Sometimes I can hear static like sound from the left speaker. The red/white RCA cables, I swapped one pair for another. if I move them in a particular way, a loud hum is emitted from one of the channels.

I cleaned my receiver (Deoxit) so what could be the possible issue here? I don't play things loud. Are all red/white RCA cables the same? No issues when listening to radio, CDs or music via my iPad and the 3.44mm cable connected to my receiver.

Thanks
Click to expand...

My Technics turntable would put out a FRIGHTNINGLY loud hum if the red (or was it the white) connector that plugged into/at the receiver was moved or disturbed.
Knowing that I lived with it for maybe 30 years. But occasionally the wire would move and the hum would come on ai a SCARY LOUD level.
Finally I just changed the ends of the RCA cables on the end that plugged into the receiver.

It appears you've tried to different sets of cables, one set cut out, the other set hummed? Both times the left channel, the odds of having two sets with the left channel (either red or white) being bad would seem to be high enough that the cause may be with either the TT or the receiver.
Sounds like either the jacks on the turntable or the receiver may be making intermittent contact and may need repair.
As for cables, it appears low capacitance cables should be used for turntables. There may be exceptions for certain types of cartridges(?) if so someone will hopefully point that out.
 
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