I have a 311 gem with a drive flashing !B1A
Also the fault on my service tool says precharge dc low
Can’t find what this means can someone help
Thanks

After a full power down and reset of the MCSS, does the fault still exist?

Whats the fault number?

Most AC drives charge the DC buss through a resistance of some sort until it reaches a set voltage where the resistance is bypassed to fully charge the buss. Otis calls this precharge and once the parameter M1 pick V PU is reached, the M1 contactors in the drive picks to bypass the resistor and charge the buss all the way.

Currently dealing with this same issue. I replaced the 4 capacitors as a starting point but to no avail. Any tips?

The drive needs to be sent out for repair.

I can get these rebuilt. PM me with pics of data tag for quote.

Access electronics out of Waldorf MD does a good job on these. I have replaced several of these over the years.
301 -645-1733

!B1A
i need your help to solve this problem
There are almost no parts left on the power floor that we haven't replaced, but the fault continues.