May have burned out a 7i77 and 7i64. What can I do to fix it?

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05 Sep 2017 16:38 #98535 by Vitran
Vitran created the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
Hello!

So after almost two months of doing a second wiring in my limited free time, I got the board back together, put it in the machine, turned it on and.... Flickering LEDs on the power supply and on the LEDs on the board.

After looking into it, it turns out I rewired 24VDC to the 5V input lines to both boards. The old wiring layout had 5V for the encoders, but it turns out the encoders are powered by the servos on this old machine. As a result I removed the 5V power supply and put in another power supply. I also thought that as all other parts on the machine and boards are running off of 24V for the fieldbus power, the boards were 24V too.

Yep. Bam. But no smoke. No sign of smoke or damage.

So, now that I have a 5V power supply, I was talking a bit on the IRC about fixing this but there were other conversations going on. I am skilled at soldering and have done a few massive chip surface mount repairs in the past.

What do I need to fix to get this back up and running, am I toast already, is there a chance the board has a 'safety' that means it is still working, or what other options do I have?

Below is the pic right before I turned on the power.

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05 Sep 2017 18:22 #98537 by PCW
PCW replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
That likely killed most of the parts that are directly connected to the 5V rail
(but not 3.3V parts running from on board regulators)

You might (briefly) power the cards up with 5V to see what if any still works
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05 Sep 2017 23:08 - 05 Sep 2017 23:29 #98551 by Vitran
Vitran replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
How can I tell what works on the board? Is there a launcher that I can see which pins or sections are running or not? The LEDs light up fine.

EDIT: I made a test drive of the board and it booted up Linux CNC with the 7i77. It booted up great! But I don't know if it is fully working. Is there a checker program?

I then made a program with the 7i77 and linked the 7i64 via RS-422/RS-485. No luck with the 7i64 as it gives the error message:

Pin: 'hm2_5i25.0.7i64.0.2.input-00' does not exist

Not sure how to connect to the 7i64 without the RS422 cable yet.
Last Edit: 05 Sep 2017 23:29 by Vitran.
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05 Sep 2017 23:49 #98553 by PCW
PCW replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
I would first check the encoder inputs on the 7I77 (you can jumper them for TTL inputs and ground the +A,+B,+index pins)
and see if the corresponding hal pins toggle)

Does the 7i77 field I/O work? ( this does need 24V on the orange connector )
(its unlikely the field i/O section got damaged but is serial interface isolator may have )
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05 Sep 2017 23:58 #98554 by Vitran
Vitran replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
Could you go into more detail about how I could wire an encoder input for testing?

I do have a 4 pin encoder (+5, A, B, Gnd) laying about, the old hand wheel from the machine, and could test each encoder input with that. Any issue with doing that test?

I am also tempted to send them back to be looked at. PCW, you work at Mesa Net, no?
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06 Sep 2017 00:03 #98557 by PCW
PCW replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
Yeah, you can test with a simple encoder (just watch the raw counts pin)

You can also request an RMA from Mesa, and we can look them over
We may also have to loaner/used cards we can just swap for a nominal fee
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29 Sep 2017 23:46 #99652 by Vitran
Vitran replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
I received a new pair of boards from Mesa. I could go on about how I checked things, but something bad happened again.

It appears that the resistance between the 5V power input pins on the 7i77 went from 48 ohms to 3 ohms when the DB25 cable is connected. I believe the 5i25 was also damaged in the power surge.

As I am not using both ports on the 5i25, I may wire the 5i25 into the second port. However I first need to find a test to see if the 5i25 is working.
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30 Sep 2017 01:04 #99655 by PCW
PCW replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
As I indicated in private email you most likely have the 7I77 and 5I25 cable power jumpering wrong
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03 Oct 2017 21:40 #99862 by andypugh
andypugh replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
Or maybe an IDC ribbon cable out-of-place?
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04 Oct 2017 01:29 #99884 by Vitran
Vitran replied the topic: May have burned out a 7i77 and 7i64. What can I do to fix it?
Andy,

PCW got me figured out. I got the boards back into the machine and have been doing PLC with power only tests at this point. I need to get the E-stop circuit working then I can move to getting main power on.

Thanks for the offer of help!
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