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MMC4 broken suspension?

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howardc64
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howardc64 posted on Fri, Jul 14 2017 5:40 PM

Got a TX2 with an MMC4 cartridge that probably have suspension failure. Thought I check with more experienced people here for reference.

First, made all the adjustments to the turntable + arms. Adjusted the platter to proper height so no more scrapes against the base. Adjusted the indicator and pickup arm to the proper height, parallel to each other, pickup arm perpendicular to the turntable. Adjusted the diaphragm for photo control so the indicator + pickup arm stays parallel during play (don't have the test record or equipment for this) Set the tracking weight to 1.2g for MMC4.

MMC4's cantilever is rotated about 30 degrees around its main axis. I can reposition it back to 0 degree with a tweezer. The cantilever definitely can be easily positioned away from being in the center of its hole. Pushing the cantilever straight back (using a tweezer) along its axis can feel a rubbery detent. Tilting the cantilever away from the record surface also feels a little rubbery detent after about 20? degrees of rotation.

Sounds has ton of distortion and skips on louder passages but fine on the quieter passages. It seems to skip less when I get the needle back to 0 degrees. Does have similar sound levels on right and left.

Clearly a broken suspension and a trip to MMC repair folks?


Last picture is after rotating the cantilever closer to 0 degrees. Cantilever's tilt angle seems to match known good MMCs I find on the net.

Beogram 4004 MMC 20EN & TX2 MMC4

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Saint Beogrowler
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howardc64:

Clearly a broken suspension and a trip to MMC repair folks?

Yes indeed. Depending on your setup and listening style, I'd opt for an upgrade when getting it rebuilt too.

Peter-

howardc64
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Saint Beogrowler:
howardc64:

Clearly a broken suspension and a trip to MMC repair folks?

Yes indeed. Depending on your setup and listening style, I'd opt for an upgrade when getting it rebuilt too.

Thanks for the confirmation Peter. Its interesting how the needle looses tracking in louder passages. I guess something about the grooves for louder passages causes the broken suspension to go haywire?

 

Beogram 4004 MMC 20EN & TX2 MMC4

Saint Beogrowler
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It is super fun watching the cantilever move like crazy on test records with different frequencies and decibels.

Peter-

MediaBobNY
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Huh?  Certainly not with the naked eye.  

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