Hey guys: I have 1998 Okuma-Howa HL-20 with 18T Fanuc controls. I had been having problems with alarm 751 (AL-27). As best I can tell, that's serial spindle encoder disconnect. I was loosing the 1 signal, cause it would rapid to position, then just sit there. So I bit the BIG bullet, and installed a new encoder on the spindle. Now I 'think' it may have doing this before encoder install, but I know it's doing it now. The spindle speed on the CRT is going nuts. Before the spindle is even turning. Even in E stop (nothing happenin but the fans turning), the speed goes nuts. Went into the Diagnostics, and found at 417, the spindle one position coder is way more whacked out than even the CRT numbers. So I removed the fan from the spindle motor, and that coder is in pristine order. Been moving wiring around and looking things over, still no clues. Had an electronic guru over, and we had a lab scope hooked to the box that the encoders feed to (both boxes), and no sign of weird signals down there. Having wondered if this was just some weird signal to the CRT, I did do some turning with it. G96 CSS caused the 751 (AL-27) alarm to come back. The 1 for the threading signal was definitely working, but threading feed rate was off the chart and varied (like the feed was trying to keep up with a wild spindle speed!). Spindle motor encoder? Spindle amp?
↧