Quote:
Originally Posted by Leon Crampin
Just to clarify the operation of the reel hubs; take up and back tension are dependent on the tape entry and exit radius. Grundig and many others use the weight of tape on the corresponding spools to vary the drive and driven torques.
On these machines, the upper hub has two concentric grooves, one to take a rubber ring which engages with the solenoid armature (large washer) for winding and braking, and the other to take a white felt ring. It's protrusion and condition are critical in achieving the right torques. The felt ring should be proud enough to ensure that the solenoid armature is fully free when the coil is not energised.
When adjusting the lower turntable height, there is a screwdriver slot in the centre shaft to facilitate rotation. Be aware that the shaft is hardened. The screwdriver blade should be slightly narrower than the slot length to avoid chipping the very hard shaft.
Leon.
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Thank you Leon for those extra helpful details. One thing I am still unsure about is how much protrusion there should be for the friction rubber pieces, obviously operational experiments will help to determine that.
But to my mind the protrusion cannot be much otherwise it will offset the felt friction operation, i.e. if the rubber protrudes above the height of the felt then the felt will not make contact with the lower hub.