Birch Model 700 phonograph tone arm and soundbox

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skrogh
Victor Jr
Posts: 15
Joined: Wed May 03, 2017 8:21 am

Birch Model 700 phonograph tone arm and soundbox

Post by skrogh »

Hi. I bought a Birch portable phonograph from the 1940s last week. It's a model 700. I'm having trouble getting it to play well. The needle gets stuck in a groove and won't advance and/or slows down. The tone arm was not moving well so I took it apart and cleaned and greased it. It's still not moving easily. There was a round collar with holes inside where it connects to the deck. Should there be ball bearings in there? I'm trying to figure out how to get it to move more freely and if it needs ball bearings. I cleaned and oiled/greased the motor but didn't pull the spring. Thanks in advance. ~ Scott

phonojim
Victor IV
Posts: 1428
Joined: Wed May 20, 2009 8:20 pm
Location: Mid - Michigan

Re: Birch Model 700 phonograph tone arm and soundbox

Post by phonojim »

Your tonearm probably needs to be sanded to better fit into the base. The tonearm is potmetal and probably swollen. Take it apart, degrease it with alcohol then sand the arm where it fits into the base. I would try 250 grit paper but go to 150 grit if the 250 loads up too quickly which can happen on some potmetal. Wipe the dust off and check it often so you don't take too much metal off. When you get it to the point that it moves easily and smoothly you can grease and reassemble it. That should solve your problem.

Jim

OrthoFan
Victor V
Posts: 2178
Joined: Sat Jul 09, 2016 7:12 pm

Re: Birch Model 700 phonograph tone arm and soundbox

Post by OrthoFan »

In addition to overhauling the tonearm, if it hasn't been done, and can be done, you might want to replace the hard diaphragm gaskets with new soft ones. Based on my experience with a Birch portable I used to own, it makes a world of difference--both in sound quality and minimizing record wear.

OF

skrogh
Victor Jr
Posts: 15
Joined: Wed May 03, 2017 8:21 am

Re: Birch Model 700 phonograph tone arm and soundbox

Post by skrogh »

Thank you very much! I'll do that and let you know how it goes! ~ Scott

skrogh
Victor Jr
Posts: 15
Joined: Wed May 03, 2017 8:21 am

Re: Birch Model 700 phonograph tone arm and soundbox

Post by skrogh »

So I was able to sand the tone arm where it fits into the base with Emory clothe. It definitely moves more freely and I was able to get it to play. However, it's still not tracking well and the sound needs improvement. I'm going to replace the reproducer gasket and rear flange. Will post update after servicing.

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