Fanuc 5T spindle drive blowing fuses

[jolulank]

Hello,

I have read a lot here before posting this thread but the threads I found did not help completely.

I have a Mori Seiki SL-3 with fanuc 5T which was working just fine and all of a sudden started to blow 2 out of the three 75 amp fast blowing fuses. Since those fuses are really expensive someone adviced me of using regular ribbon fuses just for the purpose of testing. First I used 60 amp ribbon fuses and I ended up with 2 scrs blowed up just as Al the man said I would happen in one of the threads I read. Then and after getting new scrs I tried 30 amp ribbon fuses and it works for a while, maybe a day or two( sometimes less than that and blows the fuses again. The I decided to disconnect the DC motor and install 50 amps fast fuses and the result is that it blows the within the hour having the motor disconnected.
I am running out of ideas and any help would be really appreciated.

The spindle drive model is A20B-0008-037 and it blowsthe second and third fuses (connected to S and T lines)

Thanks

jolulank

[Al_The_Man]

Quite possible the firing board is causing the problem, with SCR spindle drives it is a gamble if you replace the SCR's without having the drive board checked, trust me, it cost me a $$ before I discovered this.
Al.

[jolulank]

Thanks Al, I will look into the firing board. I am not good at fixing cards but I have a guy that does fix them relatively easy.

[tmbruno28]

firing problems can be check as follow

check in CH17 (a,b,c) with an oscilloscope. If wrong, exchange AOS04

check in CH18 (a,b,c) if wrong, exchange AOS03

if problem occurs not at eatch time, first exchange AOS03

[jolulank]

Originally Posted by tmbruno28 firing problems can be check as follow check in CH17 (a,b,c) with an oscilloscope. If wrong, exchange AOS04 check in CH18 (a,b,c) if wrong, exchange AOS03 if problem occurs not at eatch time, first exchange AOS03

Bruno,

The CH17 (a, b, c) are next to the AOS03 and the CH18 to the AOS04. Just to be sure, if CH17(a, b, c) wrong, Do I change AOS04 like you said?

Thanks

jolulank

[jolulank]

Thanks for the help Al and tmbruno,

It is working again. One of the hybrids A-OS03 (synchronous signal) was bad, it was replaced and now is working fine

Thanks again

jolulank

[electric]

dear forumers, I have same problem as you with, A-OS03, A-OS04 hybrid, I can¨t find where to buy, if anybody can help , please contact me, I am from Croatia ..

[SGARCIAM]

Originally Posted by tmbruno28 firing problems can be check as follow check in CH17 (a,b,c) with an oscilloscope. If wrong, exchange AOS04 check in CH18 (a,b,c) if wrong, exchange AOS03 if problem occurs not at eatch time, first exchange AOS03

What manual did you get the firing sequence and readings. What are the readings. While it is in command mode or stand still ?

[tmbruno28]

i don't have any manual for this spindle drive,
only about 22 years of experience