I have a Beogram 4004 which has a MMC20EN cartridge, and I think it is in good shape.  After lubricating the pivot points, the unit now works quite well except for two very specific issues, which are kind of weird:

1. If starting a 33 from the beginning, always at about 1/4 of the way into the record it begins to warble (like a cassette tape going bad).  Moving it just a bit inward, and the warbling stops.  I have both belts on order, and I suspect the platter belt is to blame, but it is weird that it only warbles at a very specific point in the travel. I would think a bad belt would be bad everywhere.

2. If starting a 33 at a very specific point (about 3/4 of the way into the record), the sound is often so distorted that you can barely make anything out.  Just lifting the arm, and placing it down again, and sometimes the sound perks right up.  The weight is set to 1 gram, and I the MMC20EN is presumably in good shape.  I have given it a thorough (and careful proper) cleaning with my Onzow Zero Dust, and although I suppose it could be the stylus, I am leaning toward something inside that maybe the moving mechanism is touching, like a wire or circuit.  Is that possible?

I am hoping that replacing the belts, and some inspection will take care of the issues, but thought I would see if these are known and perhaps deeper issues.  I do have the manual from this site as well, which I am trying to read through at the moment.

 
Thanks

Chris

I would certainly wait until the new belts are fitted before going any further than simple investigations.

One small point - the recommended tracking weight for the MMC20EN is 1.2g not 1.0 (this was for the MMC20CL), assuming it is an original B&O item then you may need to up it a little as it will be quite aged by now. The cartridge suspension will be aged regardless of the amount of use and the shape of the stylus won't matter a jot unfortunately - this would be my starting point.

Chris.

Medogsfat:

I would certainly wait until the new belts are fitted before going any further than simple investigations.

One small point - the recommended tracking weight for the MMC20EN is 1.2g not 1.0 (this was for the MMC20CL), assuming it is an original B&O item then you may need to up it a little as it will be quite aged by now. The cartridge suspension will be aged regardless of the amount of use and the shape of the stylus won't matter a jot unfortunately - this would be my starting point.

Chris.

Sorry to take so long, but now that this project is almost done, I noticed you mentioned 1.2g, but then said I would need a little more.

Would 1.3g be a good starting point?

Thanks

Chris
 

Hi Chris:

My other 4002 (DC Motor version, which is same as your 4004) does the same thing in terms of distortion.

It doesn't warble but closer to the inner diameter of the platter there is noticeable distortion especially on the high end. I don't have a secondary cartridge here to compare but I suspect that it has to to do with suspension failure.

Derek