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Fanuc error i/o troubleshooting?

rfrink

Cast Iron
Joined
Nov 21, 2005
Location
Ohio
I have a Fanuc O-MD controlled VMC that has been performing flawlessly for about 6 years.

40x20.jpg


It is a 40X20 machine that was built by Yang I think, Model SV-1000.

Today, when I fired it up I got this alarm:

crt.jpg


After checking...the air pressure was good...the gages read OK...but the alarm would not clear.

So, I took the cover off of the pressure switch, and connected the two wires together bypassing the switch. No good.. the alarm wouldn't clear.

Next, I traced the wires from the switch to the I/O board. One wire was connected to terminal "DC24VA" and the other wire connects to "319". I used my volt meter and verified that DC24VA read 24 volts...then made a jumper to the "319" terminal which effectively jumped out the entire air pressure switch with it's corresponding cord. The alarm still wouldn't clear.

I called the machinery dealer where I bought the machine...explained this to the tech guy and he said "it's a bad I/O board".

Here's the question....what is the I/O board? I have two of them.

Here is a photo of my enclosure:

overall.jpg


The pressure switch connects to a terminal strip on a circuit board located on the left hand side...noted with arrow #1. This board has a handful of relays on it. There are some ribbon cables that go from this board to the Fanuc i/o noted by arrow #2.

The board in arrow #1 seems to be from the machine tool builder with a part number: YANG SMV-600-003-1 and the Fanuc i/o mounts in a rack and has a familiar fanuc number: A16B-2203 0110/02A

So, there seems to be 2 i/o boards: 1.) The machine builder's board where the pressure switch connects ....and 2.) the Fanuc board that is connected by ribbon cable.

This is a pic of the board on the left side noted by arrow #1.

ioboard.jpg


So...any ideas where to go from here...or how to trouble shoot the electronic components.

The machinery dealer has been less than excited to get involved and I don't really have much faith in them to help me get running quickly.

Whattaya think?

-Rob
 
That's pretty typical. The MTB board (#1) is basically a power supply board. The outputs of the Fanuc board don't provide much power, so if you need more than what is supplied, you have to use a relay and a separate power source to do so. The Fanuc I/O turns on the relay, which channels the higher power. Typical of most controls actually.

If the input isn't being seen by the control, but you have the voltage to the input, chances are very good the I/O board (Fanuc) has a bad input. If there were other available unused inputs and you could edit the ladder, you could just move it to another input and change it in the PMC and away you go. Most likely it's an opo-isolator gone bad in the input board.
 
Have you checked the ladder to see if that truly is the input causing the alarm? Wouldn't be the first time I assumed the input was something and then found out it really was another.

Dan
 
if you pull that relay board that is on the left you will probly see a burnt trace
you may be able to repair
you may also be able to do your "jump thing" in this area by following traces on board and finding which pin it is in the connector between two boards

i've only had to replace one of those boards
it was on a Fortune and not terribly exspensive (3 or 4 hundred maybe)
you need to bypass the dealer and get to the manufactor/importer
but again, a person handy with a soldering iron can probly fix that thing, there are usualy extra relays that can be comandered and reused elsewhere on board.
i would also be fairly sure that your pressure switch/something (one prime suspect being little lube pump motors) pulled to much current and took the board out so check into outboard devices and add fuses where there is none for protection
 
:)You nailed it Wippin boy!

I was able to get a diagram from machinery dealer. With it, I was able to check continuity in the ribbon cables from the Fanuc I/O to through the relay board to the pressure switch.

After "ringing-out" a few connections, I quickly determined that the broken circuit was in the Relay board between point "A" on the terminal strip and point "B", a pin in the ribbon cable connector noted by the arrows below:

relayb.jpg


With a soldering gun and same small gage hook-up wire, I made a jumper.

fix.jpg


Checked it with the Ohm meter....then put everything back together.

Said a quick prayer...flipped on the power...and BINGO BAMO...I'm making chips again.


Yep..it was a bad/broken circuit on the relay board.


You guys were all great help and you've save my bacon!! Beers are on me!

Thanks again!

-One happy Dude :cheers::cheers:
 
cool

think i'd try and get some overload protection on the offending device just down from that relay board, that way what ever happened stops before the board next time.
if it gets past the relay,next thing upstream is the NC and that ain't so easy to repair
 








 
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