What's new
What's new

CHNC II Fanuc 10TF - Alarm

glbreil

Cast Iron
Joined
Feb 10, 2008
Location
McLeansboro, IL
Hello Everyone, I am getting a Bad Collet Switch Alarm on an old CHNC II with a Fanuc 10TF control.

What actually causes the alarm is that both the open collet and close collet signals are engaged at the same time.

I have determined that it is not the switch. I can completely unhook the membrane switch and nothing changes.

I can jumper the collet solenoids and make it operate but I can not get it to change in the machine.

I have some spare parts so have tried a number of things. From the control panel where the switches reside it goes to and A16B-1210-0480/02A DIDO board and I have swapped it with no success from there it goes through a ribbon cable to a large board on the the back of the CRT and from there is is fiber optic to the rack and then fiber optic to another DIDO board before going to the actual collet relays.

I can test voltages at the last DIDO board and see that both open and closed are energized. I swapped that board as well with no luck.

I could swap the board on the back of the CRT/MDI board I think it is called, but I am grasping at straws.

I am hoping some of you have had a similar problem and might have some ideas.

If I could get past the alarm I would just put a separate switch on to operate the collet closer, but it will not do anything at all with the alarm present.

Would appreciate your thoughts.

Thanks Gary Breiling
 
It has been a little while since I owned a CHNC, but I think there are two sets of collet open/close switches on the machine- one set on the keypad membrane below the screen and another on the sheet metal below the door. Is yours like that? I remember the switches below the door getting coolant in them from lifting the front cover all the time.
 
Only one set on this machine, and it is under the door, but I have completely disconnected them and it doesn't change anything.

I have also checked all of the other points I could find such as the foot switch inputs and robot inputs.

Thanks Gary
 
Not a clue about that machine and if it's a NO or NC circuit but...

If it's an NC switch that is stuck open disconnecting it will accomplish nothing.

Did you check continuity across the switch while actuating it by hand?
 
Thanks and that is a good point, according to the diagram the switches are normally open, and when I view it in the ladder it also shows that they are normally open, although both the closed collet and open collet both show active (closed) which is seems to be the problem.

As I said before I have verified that they are not whatever is triggering the open and closed collet signals, just can't figure out what else it might be.

Thanks Gary

IMG_0299.jpg
 
Attached is a diagram of the switch circuit. Also attached is a routing diagram for the machine. I have pretty good diagrams of the Hardinge boards, but they just show up to the Fanuc Boards so you sort of have to guess what is happening in there.

The MEM01 Board is the membrane control panel where all of the switches and controls reside. It leaves there and goes through 4 ribbon cables to the DIDO2 Board which is Fanuc.

I can complete unhook the MEM01 board and it does not get rid of the alarm so that pretty much eliminates the switches as a possibility.

I also replaced the DIDO2 board to see if that would be the problem and no change. I also replaced the DIDO1 board, not shown to check and no help there either. I have a CRT/MDI board but it is a little trouble to replace. I would if someone thought that might be the issue. It is the next stop after the DIDO2 board.

Thanks GaryCollet Switches.jpgCollet circuits.jpg
 
The cropped image of the switch circuit prevents me from determining if your machine is using sinking or sourcing inputs. Is it possible to post the entire schematic page?
 
Look at the collet pressure gage if it’s above 20 when the collet is open you will get that alarm. The switch is in the valve compartment it’s a pressure switch . If you look in the manual it tells you how to set it. If you can wait I will look it up on Friday . Don’t monkey around with the push buttons.
Pete
 
Here is a screenshot everything I have is to big to attach the PDF. I am not quite sure what you are looking for on the drawing or it is shown on this sheet, but here is what I have and I appreciate you taking a look.

Screenshot 2020-11-25 181538.jpg




Thanks Gary
 
Thanks I will check that, and I did see replacing and setting the pressure switch in the maintenance manual.

I do know the the collet closed pressure switch works, because when I disconnect the collet valve solenoids and close the collet by jumpering, the collet closed pressure switch activates and turns on the LED next to the collet close button, and when I open the collet, the LED goes out. There are three pressure switches in there, and I am not sure without checking what the other two do.

I will definitely investigate that.

Thanks Gary
 
Here is a screenshot everything I have is to big to attach the PDF. I am not quite sure what you are looking for on the drawing or it is shown on this sheet, but here is what I have and I appreciate you taking a look.

View attachment 305778




Thanks Gary

Your pic gets too blurry to see when I try to enlarge it. Is the vertical leg connected to the left side of the switch 0V or 24VDC? If it is 0V, then any short to ground between the I/O card and the switch will drive the input on.
 
Your pic gets too blurry to see when I try to enlarge it. Is the vertical leg connected to the left side of the switch 0V or 24VDC? If it is 0V, then any short to ground between the I/O card and the switch will drive the input on.

Thanks, I understand what you are looking at now, and yes, the switch is on the 0 volt Buss or the ground side. So with that said, I will disconnect the ribbon cables from the DIDO2 board to isolate them and make sure there are no problems there.

From the DIDO2 board there is another ribbon cable that goes to the CRT/MDI board, from there it is fiber optic cable to main board and fiber optic from the main board to the DIDO1 board. Everything on the DIDO1 board is reversed with the 24volt buss being switched and going onto the relays.

I have replaced that board as well and I am thinking that the problem has to be prior to that board since I can trace it out pretty well from there.

Without being able to see what is going on in the Fanac boards it makes it a lot more difficult to trace. Is there a source for Fanuc diagrams that did ot come with the machine?

Thanks Gary
 
Fanuc schematics were not released with machines and very rarely to service techs. At best some block diagrams of the architecture and on some early control maybe one component in on I/O. I have a few board level schematics, but not for your I/O board.

I have very little experience in how a sink type input (the input device pulls 24VDC from the I/O board to ground) is handled by Fanuc hardware. The typical Fanuc control integration is configured as source type input (input device supplies 24VDC to the I/O board) In source configuration, the initial chip on the I/O board is an opto-coupler. I suspect that is also the case in sink type configuration. I'd say a close examination of the board would determine that.

Since you have swapped boards with no change, It seem to me that there is little reason to dig into what is happening at that level.

Do you have 24VDC at the right side of the switch (as pictured in the schematic) when the switch is open and does it drop to near 0V went closed?
 
It is pretty difficult to actually check across the switch since it is a membrane switch there isn't much to get at with a meter.

What I can do is disconnect all four of the ribbon cables highlighted on the attached drawing between the membrane and the DIDO2 Board and nothing changes, so I have been thinking that removes the possibility of the switch being bad since it is no longer in the circuit.

I did figure out that I can disconnect the CB70 ribbon cable highlighted between the DIDO2 board and the CRT/MDI board and the alarm goes away.

I removed that ribbon cable and inspected every inch of it and I do not see how it could have a problem. I do have another old machine that I could removed the cable and the CRT/MDI board and try. I guess that would have to be the next step.

The only other thing that I can think of is if disconnecting the switches isn't enough. They are momentary contact switches which means they have to latch in place on the board. So maybe when they are disconnected they require a signal from one or the other (open or close) to release the position. Does that make any sense to you? If so, that could take me back to a bad switch.

If so I might be able to disconnect the membrane and switch and then operate the collet commands through the foot switch inputs. The are pretty easy to access on the Hardinge Interface Board.

DIDO2 CRT.jpg

Thanks Again! It helps to get some differnt ideas going. Gary
 
Typically in an application like this, the switches are momentary and logic in the PMC ladder program is used to latch the state.

I no longer have access to much 10 series documentation so can't research in any detail about the inter-connection between the I/O board and the MDI-CRT board. I don't remember if that is discrete or if it is using some kind of parallel data bus. I think if one were to find a 10,11,12 series connections manual that information would be in there. Probably worth some Google time.
 
I have a PDF Fanuc 10-12 Maintenance Manual. I have looked through the 500 pages of it several times, but haven't really seen a lot I could make heads or tails out of. I will give it a closer look. It does have connection diagrams but not really wiring diagrams.

I will look harder. Thanks Gary
 
....It does have connection diagrams but not really wiring diagrams.

The connections manual is targeted at the engineering department of a machine builder. It has all the interconnections of units and cable layouts with signal names so in conjunction with the diagrams in the maintenance manual it allows a tech to decipher much more of what's going on.
 
Well I have tried all of the things above with no luck.

I replaced the cable between the DIDO2 board and CRT/MDI even though I didn't think it would help. Swapped out the CRT/MDI Board with no luck there either. I also disconnected the collet switch and tried activating it through the foot switch terminals no change there either.

About the only thing left is Master PCB Board and the only one I have is about 7 versions prior to the one in this machine. Is there way it could be a software or parameter issue?

Thanks Gary
 
In post 5 you have a pic of the ladder. When you press the ADDRESS softkey does the screen show the address of the device rather than the label? If it does, please post a pic showing the ladder with the addresses.
 








 
Back
Top