ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Apparently a somewhat common problem afflicting the later linear-tracking models is that the tonearm assembly sticks mid-travel and can either cause slow retraction or lock the mechanism all together. Big thanks to Martin who helped call out the root of the issue. Just wanted to capture this on a thread for the good of the community so others can weigh in.
Problem: Arm 1609 (pictured below with yellow arrow) lifts and fouls underneath the large tonearm locating cam. That arm fits very loosely in its pivot. I don't have enough experience to know what the underlying issue with the design is but my observation is that the arm itself is very thin and prone to distortion, as well as having poor location accuracy due to the loose pivot.
Solution: TBD, would love input here. That arm seems responsible for locating the tonearm for 7" records. I removed the arm completely and not only was the problem solved but it had no effect on playing 12" records. Would love to know a fix that keeps the 7" function working but for now I have a working table again.
Tag
I understand that the lever is designed to limit the inward travel of the pu arm,ie that it can't go beyond the record label.
It can be easily reformed by heating with a hairdryer,and bending back into shape.
Another potential problem is the clutch on the carriage worm drive.I notice that you have a round cross section belt there? Martin makes a reproduction of the original triangular cross section belt.Fitting this will also improve traction.
Nick
Thanks for the response! I did get replacement belts from Martin to replace that one. That round belt had plenty of traction though. A problem I have with another one of these is that the clutch itself doesn't have enough friction to drive the arm regardless of the belt. I cleaned and re-lubed the mechanism but the clutch still slips. Anyone have any experience adjusting the clutch ?
At the underside of the tonearm positioning cam is a protruding tab, apprx 3mm "long" (in the direction of rotation).Cut 1/2mm off its height and it will clear the arm.
Rough up the clutch counterpart with a piece of sandpaper.
The problem with the round and square motor belts is usually not their friction (they are usually far too tight anyways), but because ofthe density of the rubber material they transmit vibrations from the servo motor to the subchassis, on to the platter, the record and in turn the speakers.In quiet music (and between tracks) an annoying humming sound can be heard every time the motor runs.Square and round belts are also more difficult to bend, in other words tougher and requiring more power to get to run around thepulleys and won't run as easy and delicate as a belt with only the absolutely needed amount of (light density) material present.The belts elasticity is also critical. The belt should be able to move around, stretch and shrink quite a bit withoutlosing grip (or simply fall off, as some of the square belts currently sold on Ebay as a "guaranteed fit" seems to be prone to).
Martin
Great information- thank you Martin!
Hello Dillen,
Can you help me to identify the protudring tab?
Did you mean the thin pin that must be inserted in the chassis hole?, the pin that sits loosly?
Thanks for your reply