BIC 940 Cycling Cam Question

[Flarrow13]

Hi everyone, recently I acquired a vintage BIC 940 Turntable. I have cleaned everything up and the turntable is now working amazing. The only problem i'm hoping someone could help me out with has to do with the cycling cam. For whatever reason when the turntable auto returns and shuts off, it seems that the cycling cam is going just a few teeth too far because the tonearm will lift up and move inward before the platter stops spinning, leaving the arm suspended in the air. Spinning the platter backwards seems to get it out of cycle, but this is a little bit annoying. Has anyone experienced this problem who has owned a 940, and if so, were you able to fix it?

 

[Doug G.]

Does the cam still have three pegs on the bottom or just two?

Doug

 

[Flarrow13]

One broke off, but I was able to reattach it successfully, so it has all 3.

 

[Doug G.]

It should just have 2. BIC discovered that the one nearest the trip pawl plate (the long metal piece) can cause an unreliable positive detent of the main cam. They started making the cams with just the two pegs and removed the third one on cams they had in stock. If the one that broke off on yours is either of the other 2, it is correct to repair it but if it was the 3rd one, it should be removed.

I can't definitively say this is your problem but...

Doug

 

[Flarrow13]

Just to make sure i'm understanding right, the 3rd pin closest to the trip pawl can cause unreliable stoppage on the cam when it stops spinning?

Thanks for all the help, I really appreciate it!

 

[Doug G.]

Yes, the cam can stop at the wrong place and the gear stays in contact with the gear on the platter spindle and the cam keeps turning until the table turns off.

To clarify which pin it is BIC removed, if you are looking at the bottom of the cam with the three pins so the middle one is at the bottom, the one to the left is the one that isn't necessary and removed.

Doug