a dead cartridge? Darn the Luck ! ! !

metropical

New Member
Old OM20 that I haven't touched in 20 years. Tried it direct thru my Onkyos phono pre. Nada.
Then I tried an outboard NAD pre. Left only.
I swapped sides. Right only. Pre is OK.

I reseated the cartridge wires at the headshell, both sides, 4 pins.
Tested continuity from the cartridge wire through to the NAD input. All 4 pins good.

I know it's rare, but is there something I forgot? Seems I have a dead right side.
 
use dmm/vom on the cart, should be 10-2K ohms or so. not open,
then check output at tip of cables where they go into the phono preamp
some "stupid" turntables have a kill switch so you don't get a pop/click
on needle drop. you may encounter bad contacts also.
 
If your stylus has a lot of life left, you might find another OM body on the auction site, or become a subscriber and post a wanted ad on BarterTown for an OM or even an old LM body.
 
I managed to get both sides working, however they are out of phase.
I know the speakers are wired right as I ref’d rcvr/tuner and TV.
Here's a photo of the shell if anyone has an idea which wire to flip, though I thought I tried all combos.
 

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Red wire is right channel +
Green wire is right channel -
White wire is left channel +
Blue wire is left channel -
 
And with that information, you should check the manuals for the turntable to verify the wires are in the right positions on the headshell and the cartridge which is usually well marked. The turntable side, if you have questions not answered in the manuals, can be verified using an ohmmeter from the RCA cables if there isn't a mute circuit in the table.
 
this is the odd thing.
I checked continuity from the tone arm females to the end of the RCA cables going to the pre-amp. They're fine. and in phase.
So the only thing I can think of is that the OB pre-amp (NAD PP2) is out of phase, but it's mass produced wave soldered.
The head shell isn't marked, but the cart is. Just so odd. This is the table and cart I used 25 years ago. Only the pre is different.
The rcvr is a Onkyo of recent vintage, but it's phono pre passed nothing at all. It's MM only, no MC.
 
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didja ever do something so embarrassing ..............
I was on the phone with an audio bud, going thru everything.
He asked "what input in the rvcr is the PP2 in?"
Flash of light! I switched to another input and all is well.
Though this Onkyo rcvr is only 10 yo, perhaps the RCAs on the back are hand wired rather than PCB mounts, or there is some element of the rcvr that human hands touched and flipped the phase on the one input.
Doink!
 
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