RuF wrote:
>> If those measurements were made with the turntable in the off
>> position, then you are measuring what should be a near short across
>> the cables. If that is so, then you likely have a dirty muting switch
>> or bad cables. If that measurement was made with the unit on and the
>> arm above the record, then you've got the lowest resistance
>> measurement I've ever heard of on a cartridge.
>>
>> Regards,
>> Tim Schwartz
>> Bristol Electronics
>
> Thanks again Tim. Your help is much appreciated.
>
> This time the measurements were made with the pickup on the record about
> mid point in the tracks.
>
> The results of the measurements were exactly the same as before, which
> would
> appear to suggest that there may be a problem with the mute switch. The
> RCA
> cables were installed a few months ago to replace the old 5-pin DIN plug
> and cable
> and were soldered to the same connections that were used previously. The
> original
> ground cables from the turntable are still used and are attached to the
> chassis
> of the Sony amplifier. The ground from the arm wiring is also attached
> to the same
> wires. I guess I could replace the original ground cables, if necessary.
>
> Today I'll check the muting switch and clean up the terminals and
> anything else I
> can see in that area.
I think you definitely should check that area. There should be a
difference in reading with the arm down.
Are you sure you're reading the correct scale on your ohm meter? I
couldn't remember typical DC resistances off the top of my head, so I
pulled out a few old carts and got out the meter. On an assortment of
Shure, Stanton and Pickering units (about five altogether), the readings
ran anywhere from 1.25 to 1.5 *KILO* ohms. However, before I looked
closely at the range indicator on my autoranging meter, I started to
wonder what Tim was referring to.
There's no way you could get any output at all if your cartridge was
shorted out, which is the appearance of the readings you re****t. Check
again.
OTOH, you should be reading a dead short with the mute switch closed.
Perhaps there's enough resistance in the wiring to give you a reading of
1.35 ohms--close enough--and the cart resistance is close to that
reading, but in KILO ohms, and you didn't notice the difference?
In the same drawer, which I've not pulled out in years, there are three
NOS (never used--no idea why I have them unless it was from my days as a
turntable setup tech in the 70's) Dual slide-in cartridge mounts. The
contacts on all of those are pretty nasty. IMO, it would take chemicals
or some serious elbow grease to make them serviceable. I'd pull yours
and make doubly sure that all the contacts, including the ones on the
cartridge terminals and the tonearm, are impeccably bright and ****ny.
There's a lot of potential for contact resistance there.
jak
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