RE: 1970's Sears 8 Track Repair

jw0752 — Mon, 27 Nov 2017 23:12:50 GMT

Hi Wesley,

I used to fix these things for a living 45 years ago. The pressure pad in the cartridge holds the tape snug against the head. Since the magnetism in the tape is so weak to start off with any gap or distance between the tape and the head will cause the sound to drop in and out and greatly affect the high frequency. The capstan is the shaft that the roller in the cartridge pinches the tape against. Below that is a fly wheel that helps to maintain consistent speed. The flywheel is linked to the motor by a rubber belt. When I saw how your machine was working I was suspicious of the belt first and the motor second. Time causes the rubber of the belt to deteriorate and slip. The motor itself probably has a mechanical centrifugal speed regulator. We often had trouble with dirty contacts on these motors and it would cause them to run erratically. If you remove the motor's back cap you will see the centrifugal regulator and you can easily clean the contact with a small burnishing file. Thanks for the great trip down memory lane. Oh I also wanted to mention that the head itself was mounted on a cam that could raise and lower it to 4 positions or tracks. That is what the lever is for near the top of the capstan. Each time the tape would cycle a piece of foil on the tape would trigger the mechanism to move the head to the next set of tracks. In the day we would also repair the tapes by winding them off the spool and putting them in new cases. It is quite an interesting system whereby the tape is pulled from the center and fed back onto the outside of the coil and the individual coils are constantly slipping against one another and collapsing towards the center of the spool.

John

RE: 1970's Sears 8 Track Repair

tariq.ahmad — Mon, 27 Nov 2017 21:55:48 GMT

Awesome!