View Full Version : How to test for earth ?
I think my TT has earthing problem and i would like to test it using my cheap anlogue multi. I think it may be the newish tonearm cable installed .
How do i test? I cant remember. Do i test for infinite resistance from the TT body to the earth pin on the plug? Is there more accurate test such as voltage drop?
Infinite:eek: I meant low resistance.
StanleyB
13-01-2011, 20:20
What exactly are the symptoms of the problem that you are having?
Sometimes when i pick up a Lp i get a bit of a belt as i lift it. Lots of loud pops through the spekers. Got a very loud pop when i switched of my phono amp last night. There is also a slight hum when my amp is selected for TT input.
Use the lowest resistance scale on the meter. Test from the turntable chassis and also from the arm to the earth pin on the mains plug. Do this with the arm cable unplugged, so that you're not measuring another path to ground.
You're looking for a low resistance (almost a short circuit), certainly much less than 1 ohm.
The loud pop when you turn off your phonostage is unlikely to be related to your static discharge problem. In fact, if you have a valve phonostage, it may be possible that none of your 'pop' sounds are actually static, but relate to a failing valve. Alternatively, is your phonostage properly earthed?
I never turn my (transistor) phonostage off.
If you use a brush to clean your records - don't do it on the rotating platter as this charges the record (I do sometimes, but then I don't have earthing issues).
Does your meter not have a continuity setting?
I had this problem last summer. I changed the valves and started wet cleaning my records and it stopped.
When i tested the needle didnt budge.
You don't play your records wet do you(some people do)?
...but I suspect it is not a static issue (this is coincidental), but a fault with your phonostage.
No not wet, i use a vacum. I hope its not the amp, i spent a bit getting it checked over by the manufacturer.
No not wet, i use a vacum
That'll be the cause of the noise then :eyebrows:
StanleyB
14-01-2011, 07:43
Sometimes when i pick up a Lp i get a bit of a belt as i lift it. Lots of loud pops through the spekers. Got a very loud pop when i switched of my phono amp last night. There is also a slight hum when my amp is selected for TT input.
Have you got the TT, phonp preamp, and amplifier wired into the same mains point? If not, then you should do.
Are you using a mains filter block of some sort? If so, check it is earthed.
Also check that the earth wire from the TT is properly connected to the phono preamp.
You appear to have a floating earth somewhere in your system.
The tonearm wire has two earth leads. The one nearest the tonearm i have put onto the pitch fader the other end is on the pre amp so its not really connected to the power amp. What would be the best way of doing that ?
Everything on the system then goes through a mains block.
StanleyB
14-01-2011, 14:04
I don't know the 1210 inside out any more, but I am a bit puzzled why one earth wire from the tonearm is going to the pitch fader :scratch:. Did that wire go there before with the previous arm?
Yes the previous tonearm cable attaches at one point, a screw that holds the pitch fader to the main body.
Use the lowest resistance scale on the meter. Test from the turntable chassis and also from the arm to the earth pin on the mains plug. Do this with the arm cable unplugged, so that you're not measuring another path to ground.
You're looking for a low resistance (almost a short circuit), certainly much less than 1 ohm.
Martin, the mains cable is double insulated so what earth doi use?
Do you mean there is no earth connection from the deck, i.e. the mains cable is two-core? In that case, your deck will rely on its earth from the preamp via the tonearm cable earth.
Yes its tw0core martin. I thought that might be standard !
So i will test the plug on the pre ampand if there is a slight resistance then i have a problem i guess.
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