[Robyr]

Hello, I've got some turning machines which use the Fanuc servo amplifier A06B-6096-H206 that, at the moment of switching it on, displays the 8 alarm: ABNORMAL CURRENT.

If I wait a period lasting from some minutes till an hour (depending on how recently the problem firstly appeared), switching the turning machine off and then on, the error disappears.

Another solution we succesfully experimented is to warm up the servo with an hair-dryer for a couple of minutes and then switching it off and on.

Starting from the fact that this malfunction is probably due to a simple ageing component, I'd like to know if anybody has identified which is the component/components that I have to replace.
I find it irritating substitute an entire servo when the problem probably lies on a cheap component!

Thank You in advance for helping me solving this.
Regards

[mike_Kilroy]

.......Another solution we succesfully experimented is to warm up the servo with an hair-dryer for a couple of minutes and then switching it off and on....

by 'servo' do u mean the servo motor or the servo drive? I assume from ur description u mean servo drive but it seems more likely the servo motor actually has an issue, like it has moisture in it and the fault is really telling u it is time to get it cleans and reinsulated?

[Al_The_Man]

I have come across this in some Fanuc systems and turned out to be the motor temperature sensor, if the feedback from this is wrong for any reason the control thinks the motor has overheated, which is usually due to excess current.
Al.

[Robyr]

I have come across this in some Fanuc systems and turned out to be the motor temperature sensor, if the feedback from this is wrong for any reason the control thinks the motor has overheated, which is usually due to excess current.
Al.

If it is the temperature sensor, because with heating the servo amplifier does it work? I'm not heating the motor!

[underthetire]

Typical failed capacitor in the drive. Seen that one before many times.

[Robyr]

Typical failed capacitor in the drive. Seen that one before many times.

I agree with you! But which capacitor? Have you an idea?

Thank You.

[mike_Kilroy]

probably the BIG ONE(s) - dc bus that keep bus voltage solid.... makes sense...would match all your facts and findings....

[kirkchabot]

I agree bad cap or input voltage on the low side

[KENGLIAN]

Use a Blue Meter to check the bad capacitor. Normally is at the output section near the IGBT especially the SMD Cap. Blue meter is a must equipment to check Capacitor.

[terrisinovare]

I'm thinking of checking two big caps you can see it in attached picture. I am right?

[KENGLIAN]

Normally, abnormal current is caused by: Bad IGBT, Bad SMD resistor under the IGBT and steel bar (shown in your picture) or small capacitor in the Control board (the board on top of your picture).
Use DMM to check the value of resistor, replace if the value change.
Blue meter for capacitor. Remember to discharge the capacitor before you test. Replace if ESR value is high
For IGBT, just replace it because it is not easy to test a IGBT module.
Hope this will help.

[terrisinovare]

Is it possible to check resistors in board? Or should I dismount it from the board?

Normally, abnormal current is caused by: Bad IGBT, Bad SMD resistor under the IGBT and steel bar (shown in your picture) or small capacitor in the Control board (the board on top of your picture).
Use DMM to check the value of resistor, replace if the value change.
Blue meter for capacitor. Remember to discharge the capacitor before you test. Replace if ESR value is high
For IGBT, just replace it because it is not easy to test a IGBT module.
Hope this will help.

[terrisinovare]

As I am very new, by IGBT you mean this part I marked in circle?

[KENGLIAN]

Yes. Confirm off board if value is not as indicated.
IGBT should be FUJI 6MBP ## XX ###

[terrisinovare]

Thank you for your answer. IGBT module is FUJI 6MBP50RA060-01 . Visually inspected all the capacitors on the control board, all seems okay( didn't see any blown capacitor). Now I will check the resistors .

Yes. Confirm off board if value is not as indicated.
IGBT should be FUJI 6MBP ## XX ###

[terrisinovare]

I found some melted marks on board for a resistor If I understand you correctly i need to check all these resistors?