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wanders 1st October 2012 03:15 PM

Moving Coil Cartridge Question
 
I've been fighting what I thought was a turntable grounding problem while using a moving coil cartridge, Denon dl-103r. After a lot of frustration, I think the problem might be with the cartridge itself. Using a digital multi-meter, I found that the Denon has electrical continuity between the signal and ground post in each channel. Checking a moving magnet cart (A/T 12), there is not similar continuity.

Is this behavoir to be expected in the moving coil Denon?

Thanks

SY 1st October 2012 04:42 PM

An MC has far lower resistance in its coils than an MM. That would explain your readings. There are lots of ways to get a hummy setup and very few ways to have a hum free setup, so keep plugging at all the other possibilities.

wanders 1st October 2012 06:15 PM

Quote:

Originally Posted by SY (Post 3186366)
There are lots of ways to get a hummy setup and very few ways to have a hum free setup

Boy, that's the truth.

Thanks, Sy.

user510 1st October 2012 06:27 PM

Usually, the grounding problem can be located through simple continuity checks. Perhaps a broken solder joint at an RCA plug. Or a break within the tonearm wires.

Getting just the right fit between cartridge clips and posts seems to be an art arrived at through practice. Needs to be a snug fit.

Oxidization of the metal at all the connection joints is something to be chased away.

stuff like that.

-Steve

Holger Barske 1st October 2012 06:40 PM

The Denon DL103R is specified with a coil resistance of 14 Ohms. This can easily be mistaken for a short.

wanders 1st October 2012 07:05 PM

Quote:

Originally Posted by Holger Barske (Post 3186497)
The Denon DL103R is specified with a coil resistance of 14 Ohms. This can easily be mistaken for a short.

Good input, thanks.

Quote:

Originally Posted by user510 (Post 3186482)
Usually, the grounding problem can be located through simple continuity checks. Perhaps a broken solder joint at an RCA plug. Or a break within the tonearm wires.

Getting just the right fit between cartridge clips and posts seems to be an art arrived at through practice. Needs to be a snug fit.

Oxidization of the metal at all the connection joints is something to be chased away.

stuff like that.

-Steve

I've been doing continuity checks for a while and re-soldered several suspect connections. I usually, work on it when I've got an hour or two over the weekend. It's a mechanically complicated Pioneer PL-570, a bother to disconnect, and a risk that I might screw up something when poking around. As noted, in a perverse way, it would have been a relief to blame the whole thing on the cart (an expensive relief, however). I'll keep looking.

Thanks.

kimon 1st October 2012 09:20 PM

I wonder how did the coils in the cartridges survived the continuity test!

vinylkid58 1st October 2012 09:46 PM

Quote:

Originally Posted by kimon (Post 3186688)
I wonder how did the coils in the cartridge survive the continuity test!

Maybe they didn't.:eek:

jeff

Holger Barske 1st October 2012 10:02 PM

In fact putting an Ohmmeter on the coils of an MC pickup isn't the best idea at all. Just adding a few Kiloohms in series eliminates the danger, and basically offers the same results (a few kiloohms - coils are fine; open circuit - coils are gone).

SY 1st October 2012 10:12 PM

I'd guess no problem- the current through those testers is usually relatively low, and the low coil resistance means that any power dissipated is minuscule.


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