Both problem units have had the tachs replaced and calibrated. New drive setups done. Pulse scale is within spec +/- 5 of 250.
All voltages and contacts have been checked, yet I’m thinking it must be a flakey contact or a voltage value slightly off. Or pulse board?
Any thoughts would be greatly appreciated.
The units are a very old Otis gearless, double wrapped 1:1. They are running 500 fpm with the scd drive. We do have the laptop to hook up as well.
Thank again for the response. I’m sorry I’m not familiar with the high speed nulling procedure. We adjusted the tachs offset to each other and scaling on inspection speed. The tach bands are tight, but could possibly be tighter.
Maybe a silly question but, is drive fault 99 (excessive tach error) strictly related to the tachs? And is error threshold adjustable
I swapped out one of the tachs on the most problematic unit this afternoon. I also added 2 polycords(only had 6 out of 8).
Adjusted insp speed and pots as mentioned, performed learn and the pulse scale came in at exactly 250!
Time will tell.
Thanks again