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 Post subject: How to decouple a plano -reflex arm.
PostPosted: Fri Apr 05, 2019 7:43 am 
Victor Jr
Joined: Sat Apr 07, 2018 9:15 am
Posts: 41

I started (haven't found the time to finish!) restoring a Columbia 100 portable. As you might know, the tone arm on these shrink and can skate the surface of record. And it appears fatal to disassemble for cleaning and re-greasing. I want to share with you how I successfully decoupled the tone arm, with zero damage. I have some pictures, and am editing a video of the process.

First, I removed the screw on the base.
Then, I whittled down the end of a bamboo skewer (my favorite cleaning tool) so that I had a long, narrow strip.
Next I carefully inserted this into the space between the arm and the base and "fished" for a bearing, and moved it into position above the slit on the base.
Lastly, I inserted the skewer into this and gently played with the bearing until I was able to leverage it though the hole on the top of the arm.
Once I had removed all the bearings in this way, the tone arm easily separated from the base.

After cleaning and re-packing the bearings with moly grease, I punched a 1/32" fiber gasket to fit between the slit on the base, to prevent over-tightening.

Honestly, I don't think this helped the loose fit as much as I had hoped. Maybe a different grease? New bearings one size up? I am still working on cutting a cork gasket that will raise the tone arm high enough without preventing the case from closing. Any suggestions?

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 Post subject: Re: How to decouple a plano -reflex arm.
PostPosted: Sat Apr 06, 2019 5:36 am 
Victor III
Joined: Sun May 27, 2012 2:38 pm
Posts: 883
Location: United Kingdom
The problem with these arms is that the pot-metal bases do not swell evenly, so the inner circle that takes the ball bearings is permanently mis-shapen. Trying to put larger ball bearings in will not work, as they will only drop in where the base is at it's largest diameter, and not where it is at it's original diameter. If you do manage to get them in, it will result in the arm binding in some places, and possibly breaking the base, which is very fragile. I had four of these 100s sitting on a shelf for years waiting for replacement arms, but with the chances of finding such things being next to nil, I reluctantly scrapped them.

 Post subject: Re: How to decouple a plano -reflex arm.
PostPosted: Sun Apr 07, 2019 11:35 pm 
Victor V
I've got both kinds of music--classical & rag-time.
Joined: Fri Oct 06, 2017 11:39 am
Posts: 2104
Location: South Carolina
Thanks for saying how to do this. Not often does anyone take apart portable arms--this should help out a collector down the road immensely.

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