Hey guys, I've been waiting to be approved for this forum for a while. Thanks for having me aboard.
While I was waiting, I described at length a problem I'm facing with an Otari MX5050 B-II. The full detail w/ pictures etc can be found in
this gearslutz thread. Long story short, my capstan spins too fast... about 1.4x too fast at 15 ips. So when I load up a 15ips cal tape and play the 1kHz section, the machine outputs 1.41kHz.
Speed controls (either on the front of unit or back of main PCB) have no effect. They controls DO, however, work. Changing speed settings results in the correct voltages hitting the capstan servo PCB. This led others to suspect the tach feedback coil, tucked at the bottom inside the capstan motor housing. (It looks a lot like a playback head).
So I removed that from circuit, and found that the coil was open. Or at least, there was no continuity between the two poles when using a DMM. This should test like any other coil, no? Anyway, I took the one from my parts machine, removed that from circuit, and again saw no continuity. Unsure of whether these test results meant the coils were working or broken, I installed the replacement pickup, reassembled the motor and installed it.
Unfortunately, normal operation was not restored, though playback now fluctuates in speed (with no modification to controls). One possibility: the 2nd tach pickup is also broken... Anyone have any ideas?
Thanks in advance, and I look forward to being a part of this community.