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Perplexed by Sonus Blue - could be it's shot?

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Perplexed by Sonus Blue - could be it's shot?

Postby 62vauxhall » 10 Oct 2017 12:48

When I picked up a turntable two weeks ago I planned to mount a Sonus Blue (circa 1978) which I did. Very quicly, the turntable exhibited a problem with restricted arm movement but was able to play the first 5 minutes or so of an LP. During that time the Sonus worked properly and sounded good enough to make me look forward to more lengthy listening.

The turntable went back to the shop it came from to remedy the arm problem which was done the same day but when re-connected, only the right channel produced sound.

At first I looked elsewhere before considering the fault originated at the turntable. I installed a different headshell and cartridge and both channels were fine. I plugged in the Sonus/headshell combo again and still a dead channel but now also hum.

Long story short:
the Sonus has 315 ohms on each side,
there is continuity from the cartridge leads to the RCA plugs,
there is continuity from one end of the cartridge leads to the other even when pulling them back and forth - taught to loose,
the cartridge terminals have been cleaned,
the cartridges ends of the leads have been cleaned,
the headshell ends of the leads have been cleaned,
the headshell pins have been cleaned,
the headshell contacts entering the arm have been cleaned,
the contacts within the arm are shiny bright.

Can one conclude then that there is something amiss with the Sonus cartridge despite measuring 315 ohms on each coil? Because it would seem to me that since there is equal resistance on both sides, there is continuity so therefore the coils are good.

Might be worth mentioning that when the Sonus is in place, the hum intensity increases the closer one's fingers get to the headshell.
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Re: Perplexed by Sonus Blue - could be it's shot?

Postby rread13 » 21 Oct 2017 16:55

Pictures would help of your set up. Or more information on turntable/headshell arm?

The hum is a grounding and or corrosion issue in most cases. If your table has a removable headshell the 4 contacts at the headshell and in the arm have you cleaned them with something like an eraser? Something to shine up the oxidized surfaces to make clean electrical contacts.

How about the tables RCA cable? Has it been changed out with a new low pf cable and a new grounding cable? Something to consider if not.
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