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cassette deck servos

A

ampegdan

Super Member
Hi all-
I'm working on an old Realistic sct-33 silver cassette player with two servo motors for actuating the functions. Each servo has three positions, with the center(#2) one being "neutral". Pins on the ends of the servo shaft engage a sort of pivoting actuator which is linked to everything else. For play, both shafts retract to position#1, for fast forward bottom one goes to#3 and top to #1, for rewind top goes to #3 and bottom to #1.
The top servo has a problem getting all the way to postion #3. If I nudge it with a pencil point, it'll click into position and rewind. If not, the machine shuts the rewind function off after a few seconds(this is a soft-touch machine).
Anybody ever run across this? Am I looking at a bad servo or a voltage or linkage problem? FF and play work fine. I just replaced the small belt from the motor to the idler; the functions didn't work before at all. That belt is a tad tight, but I don't think it would cause something like this, would it?
Any input would be appreciated, but I know this is a football day so I won't hold my breath.....
Dan
 
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I have a STC-33 and I do recall that the supply reel must be turning for the capstan to remain engaged. If it stops the capstan will disengage after a few seconds. I also think that would mean that the belt for the counter has to be functioning. All that may have absolutely nothing to do with your problem but if you are not aware of it that kind of thing can drive you nuts. At least it could drive me nuts. I do have an owners manual somewhere and can scan it for you if you need it. I will look to see if I have a service manual and I will send you a PM if I do. If you need a virtual A/B comparison or a function check, just let me know.

The STC-33 is an excellent tape deck, possibly the best one that Radio Shack ever "made". I don't know who actually manufactured it.
 
I've been looking for something sticking but there's not a lot hanging out with this thing. I need to figure out if there's another way to access the mechanism rather than from the back while keeping the functions, uh, functional. The supply reel never gets a chance to start when the servo doesn't kick it on. That'd be great if the service manual surfaced somewhere. The owner's manual certainly wouldn't hurt, but we'll see if I get it going first before putting you to that much aggr.
Something like this won't DRIVE me nuts-it's only a short putt from here. If I wasn't half wacko why would I be spending my free time fixing a broken Radio Shack cassette deck, TOTL or not?
Thanks for the tips
Dan
 
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