Does anyone know what I should do when I get the A-24 alarm on a blood pump? I changed the whole module and still have the alarm.

LP955 board.

Say what, I'm new to all of this. just where can I find that board?

According to Fresenius.
A.24 alarm code.

Optical sensor frequency (tach) not in range.

Check or replace in the following order:
*Motor/Tachometer assy.
*LP955
*LP956

This is the link for the blood pump alarms.

http://www.fmcna.com/fusa/fieldbulletins/04frk004.pdf

Are you certain the replacement module was good? Did you try it in another machine?

I did switch it to another machine and the problem followed.

nine out of ten times, whenever I have a blood pump alarm, i replace the motor tach assembly. The rotor sensor, and the boards seem to be short term fixes. It is somewhat discouraging to encounter blood pump repairs on machines with only 12,000 hours.

These machines have 30,000 hrs on them. H&S will warranty the part so I'm sending it back.

If the motor and tach assembly is the problem, the best fix is to replace the motor with a new one. Replacing the brushes is a temporary fix from what I've experience. The cost for a new one is almost the same as a H and S rebuild.