Optonica RT-6505 Motor

[lawyerjim47]

Found a real nice Optonica RT-6505. Belts (main and tape counter) are a bit loose, but still turn parts as intended when I turn them by hand. There is a small idler tire that is still solid and makes contact. There is a fuse, but it is fine, and all lights turn on except the one behind the tape. However, I cannot get the motor to turn on. When I hit play/rw/ff, the switches stay down for a couple of seconds (like when the tape ends), and then pop back into place. The spindle on the motor can be easily turned, and while it is hooked up to a circuit board, there are only two lines going out so nothing seemingly electronically weird.

Checked the power board but nothing looks iffy. (That is about the extent of my electronics knowledge).

Question: motor dead or something else?

Thanks,
Jim

 

[oldvinyldude]

There is some sort of tach that senses that the take up spindle is indeed turning (indicating tape is being wound onto the take up spool). When the tach fails to sense this, it shuts off the transport, because the tach system is there to do autoshutoff at the end of tape, and to stop the deck if the take up is not moving, so tape jams are avoided.

This tach is frequently driven off the tape counter drive. If the belt is slipping, it can cause the autostop to engage. Look near the counter for a driven wheel that has a disc with cutouts, running between a tiny sensor (The sensor will have 2 wires attached, typically). That is the tach-enter play mode and look to see if it's spinning. No tach spin-shut down occurs.