Simple fix for sagging counterweight on Ortofon tonearms
When I acquired my RMG309 a nylon tie was wrapped to support the sagging counterweight due to a deteriorated rubber tube that decouples the counterweight from the rest of the tone arm assembly. Since I was restoring an SME 3009 that had the same problem I ordered an extra set of rubber decoupling tube which fits the Ortofon but was too soft to support the more massive counterweight. What is required is a harder type of rubber tubing available from an auto supply.
Fixing the problem is very simple. To disassemble, loosen set screw [1] to release the spring, set screw [2] to remove the counter weight and then carefully pull out the short aluminum tube [3]. Remove all the deteriorated rubber inside the short aluminum tube [3] as well as on the other end towards the gimbal bearing tower [6]. Using fine sandpaper sprayed with a burst of WD40 clean the short metal shaft [4] until it is smooth and shiny. This will later be force fit into the new rubber tube [5] which is a 1/4" OD and 1/8" ID rubber tubing approximately 1 3/8" long I found at a local auto supply for .75 cents a foot. I did not bother to crazy glue the rubber tubing since there was enough resistance in the fit.
This is how it looks after reassembly.
Hi - thanks for this helpful post.
ReplyDeleteI have the same issue with an RMA309 but I can't really get the short aluminum tube [3] out. I have removed both screws in the hole on the counterbalance [2] - but the rubber sleeve and the tube won't budge.
I don't want to damage anything, so I thought I'd get your advice first. Did you simply pull it out by force?
Regards,
Claus
When working with tonearms, I never use force. In my case the counterweight (2), short tube (3) and short metal shaft (4) fell out in one piece because the rubber was very dry.
DeleteI've always wondered if the metal shaft was permanently attached inside the bearing tower. I guess I'll never know. I rebuilt mine almost 20 years ago and holds its own compared to the '90s Japanese reissue RMG309i and Bokrand AB309.
I hope that helps!
JE
Thanks for your reply JE.
ReplyDeleteMine really won't budge. The rubber on mine is orange and appears to be thicker so perhaps it's just really sticking to the tube. Perhaps a little WD40 will help.
The rubber damper was also orange in mine. Cleaning up the residue was a pain. I used a solvent - paint thinner or maybe acetone?
DeleteHi JE. I put aside my project for a while but just finished fixing my tonearm using your guidance. It was indeed a bit of a PITA! Thanks for a great post!
ReplyDeleteI'm glad you finally sorted it out. Enjoy your RMA309!
DeleteHi again. Researching these arms has proven more difficult than expected. Ortofon lost all their documentation for their older products, so they're not much help.
DeleteBut through translating Japanese websites, it appears that my arm is an RM-309, which predates the RMA version. It is apparently distinguished by having 0-10 on the counterweight scale in stead of 0-6 on the RMA and the RMG models.
I noticed your scale is also 0-10 - suggesting that your arm is also an RM-309 (provided that the Japanese info is correct).
I also refer to Japanese magazines and websites for info on vintage audio since they pioneered the rediscovery of classic hifi equipment. However, due to the passage of time and lost documentation, no matter how fastidious a research was conducted, accuracy isn't always guaranteed.
DeleteAFAIK, all the vintage Ortofon mono MC cartridges were supplied in an A-type head. Hence, the A-type tonearms were developed in the mono era.
That said, 0-10/0-6 calibrations aside, I'd still consider mine an RMG309 since it was designed for the "G" type SPU (Stereo Pick Up) head, which, IIRC, was introduced in the stereo era to fit small SUTs inside = SPU-GT. Besides the existing brochure published in the official Ortofon website called it an RMG309.