[Mnagibulla]

Hello,

I am an EE and my company has a Excel PMC-5T18 that has a FANUC series 21-M.

Two days ago the machine stopped and I was asked to help get it start it again. Now I am a new graduate EE and so I have no experiance on this machine what so ever. However, we found out it was a fuse that was switched in the back. On one of what I believe is a relay. After switching on again we noticed that whenever the machine load increase when its working it stops and gives an error message of ERROR 751 1 AL-03.

I searched a bit and found it is a blown fuse, but I have no idea where and which fuse that is that I need to replace and what caused this in the first place.


Any ideas on this error?

EDIT1:
So we ran some tests to see when exactly this happens, and we found out that it shuts down when we add coolant. If we don't the machine runs fine on any settings. Hopefully that helps if anyone know why that is happening.

[drdos]

Does this machine have a built in spindle motor? If so then sounds like coolant is getting into the windings.

Alarm code 03
The fuse of the DC link has blown. (The voltage at the DC link is
insufficient.) This alarm is checked when emergency stop is cancelled.
(1) If this alarm is issued during spindle operation (rotation)
The fuse of the DC link inside the SPM has probably blown. So,
replace the SPM. This alarm may be caused by the following:
<1> Power line short-circuited to ground
<2> Motor winding short-circuited to ground
<3> IGBT or IPM module failure
(2) If the PSM input magnetic contactor is once turned on and is
turned off with this alarm when emergency stop is cancelled or the
CNC is started (When two spindles are connected, the magnetic
contactor may not be turned off.)
(a) The DC link wire is not connected.
Check the DC link (TB1) wiring for errors.
(b) A cable is faulty.
Pin 9 of the interface cable (JX1B-JX1A) between the PSM
and SPM may be short-circuited to 0V. Replace the cable.
(c) The fuse of the DC link inside the SPM has blown.
Replace the SPM.

[gugu]

In my case, the 2 resistors R51 and R52 on the DC buss were open. The resistors are on the main board of the Spindle Amplifier (not on the communications board).
Replace the 2 resistors at it might solve your problem. I've been searching for a solution all over the internet and couldn't find anything that worked, so now i decided that every time i solve a problem and fix something, i'll post it everywhere for anyone to see.