7i76e burned - after setting up VFD

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17 Jul 2020 10:15 - 17 Jul 2020 10:19 #174927 by denhen89
Hello,
yesterday with the help of PCW i got the vfd setup so that the motor turns in both directions by using m3 m4 code.
Just a hour ago i went to my workshop to get the rpm scaled. First i set up the VFD to use sensorless vector control and changed from 50hz to 60hz. Also i setup the correct motor current, rpm, etc..
I started the spindle couple of times, it worked, but i wanted to check the torque at lower rpm, like 100rpm, so the motor was running for about 10-20 seconds, then i just heard a strange sound coming from the 7i76e card and saw that somewhere from TB6 comes smoke out. I then switched off the 24v supply.

Some important notes: Yesterday i got some "over current message" as well as "over temperature" when i started linuxcnc. I have then read here somewhere on the forum that ther output pins terminal might be broken and it can be tested by taking off all output pins, so it did that and after a restart of linuxcnc it worked. I then movved all output pins to TB5. That worked.
I have also read that if those Error messages showed up, then the card should be repaired otherwise more damage can happen to the card.
Today on the first start up i got those 2 error messages again, so i took off the TB5 output terminal, restard linuxcnc (no error message) and put back the output terminal.

It seems that the U5 ON Semiconductor is damaged. This i think just because from that area came smoke out and also optically it looks like it is damaged.
Take a look at this video and the picture:

(on the video you see that those wiring dont look clean or so, but this is only for now until everything is done with the wiring. No unused wires has touched some pins or so.


If only that U5 On semiconductor (type: NCV7608) would be broken, then i have someone who can for sure replace it, but also i dont know where i get it (on aliexpress for sure, but i dont want to wait that long)

I hope you guys can help me out again. I am really frustrated right now, because i was careful when doing the electrical jobs, even i am not a electrician and as i said, everything worked well, but only for some time, so i can not understand why that heppend.
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Last edit: 17 Jul 2020 10:19 by denhen89.

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17 Jul 2020 10:45 #174928 by gerritv
digikey.com, mouser.com both show stock.
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17 Jul 2020 10:58 #174929 by Aciera
U5 is definitally destroyed.
The cause is difficult to diagnose since we don't know how you wired everything up.
You might want to check what kind of components you have connected to those outputs. Are there large or many inductive loads (i.e. coils) ?
The other thing is that the 24V field power supply is not supposed to be switched on the DC side. Meaning no disconnections between the 24V Power supply and the 7i76e.

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17 Jul 2020 10:59 #174930 by denhen89
Have found them already but thank you very much. I found the complete model number NCV7608DWR2G here on the forum, but with only the main number I wasnt sure.

Driving now to my electrician who already represents my MPG encoder a month ago or so. I hope nothing else is damaged.

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17 Jul 2020 11:15 #174931 by denhen89
My electrician is unfortunately until tomorrow on vacations, so I will order 2PCs and hope they arrive soon.

Also I hope that nothing else is damaged but I don't know how to check that.

On the outputs I have only 2 LEDS from the machine on and pause/resume button and the spindle CW and CCW signal to VFD.

I am using a 25v seitching power supply from a TV, that can be discounted by taking of the DC plug.

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17 Jul 2020 11:25 - 17 Jul 2020 11:27 #174932 by Aciera

be discounted by taking of the DC plug.


If that means that you pull the plug on the dc (24V) side then that might be something that damages the driver chips.
forum.linuxcnc.org/27-driver-boards/3782...ugging-advice#150491
forum.linuxcnc.org/30-cnc-machines/39372...7i77?start=20#172858
Last edit: 17 Jul 2020 11:27 by Aciera.
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17 Jul 2020 11:38 #174934 by denhen89
I have to say that i usually have not done that this way, but yesterday i have so many problems with the setup of the VFD and had to rewire so many times, that i have for sure disconnected it that way.

If you are talking about driver chips, then you mean the chips (NCV7608DWR2G) for the output pins, correct?
If only the driver chips are broken, but nothing else, then this is not that bad. Just couple days lost, because i have to wait until they arrive and get replaced by my electrician.

PS: Thanks for the links. I have read them. I did not know that something can break when taking of the DC plug from the switch instead of unpöugging it from the 220v plug.

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17 Jul 2020 13:45 #174944 by tommylight
Moved to "driver boards" .
P.S.
Question for PCW:
What are the implications of removing that chip or disconnecting the supply to it?

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17 Jul 2020 15:05 #174947 by PCW
I don't think you can just remove the part as the CPU expects status information
back from the driver chip

Driver damage on the 7I76/7I76E/7I77 is usually traceable to live switching the field power
(driving large relays/contactors without flyback diodes can also damage drivers)
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17 Jul 2020 18:14 #174951 by tommylight

I don't think you can just remove the part as the CPU expects status information
back from the driver chip

Thanks for confirming that.

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