Need Help!- Fanuc 6MB stuck in jog mode

[Andy Fritz]

Machine Hitachi Seiki VA-35 with Micon 8 and Fanuc 6MB.
For some reason Jog is active even when the mode selector is set to hand wheel, mdi, memory or edit. I checked Diagnostic #105 and #41 and there is a steady 1 on bit 2. The mode selector knob seems to work as I also get a 1 on the other bits when it is set to handle, mdi etc. I tried to disconnect the C02 Honda plug from the NC, got the expected alarms, but still the 1 on bit 2 in Diagnostic #41 and #105. This means the signal is generated not by the mode selector but somewhere else. The only manual I have for the Micon 8 is some brief instructions regarding the tool changer. I do have a wiring diagram and ladder in japanese, but dont know what to make of it.

On the Fanuc side, I dont know if diagnostic 41 and 105 is only showing what the NC is receiving from the operator panel or if it is also showing what some relay is outputting? When I disconnected the C02 honda plug DGN 41 and 105 did not reflect when turning the mode selector. Only the steady 1 for the jog mode. If DGN is only showing the NC receiving the signal and NOT another relay it would seem logic that the signal receiver for the jog signal is bad. If so how would I track it down? Or would I have to replace the whole board?

Any ideas?

Cheers,

Andy

[Al_The_Man]

Normally you would see a binary pattern in the diagnostics when the mode switch is rotated, it one bit is on permanently, it could mean defective switch or input, check with a meter.
Al.

[Andy Fritz]

Originally Posted by Al_The_Man Normally you would see a binary pattern in the diagnostics when the mode switch is rotated, it one bit is on permanently, it could mean defective switch or input, check with a meter. Al.

Hi Al,

Yes the pattern is seen on DGN41 and 105. Could you just check if my assumptions are correct?

1. The mode selector switch is connected to the I/O board by the C02 honda plug cable. True?

2. The DGN 41 and 105 shows the state of the input signal receivers (relays?) on the I/O board. True?

3. If I disconnect the CO2 honda plug from the I/O board and still get a 1 on bit 2 (jog) on DGN 41 and 105 it means that the input signal receiver (relay?) is broken. True?

Cheers,

Andy

[alexfanuc]

If you have another I/o board in the machine you might want to swapt it.
See if the problem is still there.
Whatch out for the jumpers on the board.

Regards,
Alexfanuc

[Andy Fritz]

Originally Posted by alexfanuc If you have another I/o board in the machine you might want to swapt it. See if the problem is still there. Whatch out for the jumpers on the board. Regards, Alexfanuc

Hi Alex,

Unfortunately there is only one I/O board. It is a A20B-0007-0040/ rev 03A.
I had a quick look for one and the only available on ebay is USD 700. A bit steep just to see if the board is the problem...
I tried a diode check between the incoming pin for jog mode and some random points on the board and did not get one single beep. Then I tried the incoming pin for Handle (MPG) mode and got loads of beeps. I wonder if the I/O board pulls the voltage low when a signal is active and high when not active?

Andy

[ben_heinman]

I've had it before where a door interlock switch on the electrical cabinet wouldn't allow mode change. I don't know if your machine is equiped with them but you can check if the doors are closing fully or if the switches are working.

[Andy Fritz]

Originally Posted by ben_heinman I've had it before where a door interlock switch on the electrical cabinet wouldn't allow mode change. I don't know if your machine is equiped with them but you can check if the doors are closing fully or if the switches are working.

Hi Ben,

Thanks for your reply. That is likely not the case here as the door interlock must have been removed years ago. We have been running programs with both doors open in the past. I am fairly certain we have a bad Fanuc I/O board so I am now waiting for a replacement. I just wish I knew how to trace down the offending relay or op amp (or what ever they are called) so it could be a USD 10 fix instead of a USD 700 fix every time something fails!

Andy

[alexfanuc]

Originally Posted by Andy Fritz Hi Ben, Thanks for your reply. That is likely not the case here as the door interlock must have been removed years ago. We have been running programs with both doors open in the past. I am fairly certain we have a bad Fanuc I/O board so I am now waiting for a replacement. I just wish I knew how to trace down the offending relay or op amp (or what ever they are called) so it could be a USD 10 fix instead of a USD 700 fix every time something fails! Andy

Check connector C02 pin 5 at the I/O pcb and check where it is going to.
Here is a copy of the pins of the connectors.

Alexfanuc

[Andy Fritz]

Originally Posted by alexfanuc Check connector C02 pin 5 at the I/O pcb and check where it is going to. Here is a copy of the pins of the connectors. Alexfanuc

Hi Alex,

Thanks for the diagram. I have checked pin 5 already and what goes into the board is fine. To repair the board I would need some info on how to trace the signal to the IC's. Again this is less urgent as I have already ordered a replacement board.

Andy

[Andy Fritz]

Just to finish off this thread in case someone else gets the same problem;
It was the Fanuc I/O board. Got a new one, popped it in and everything works again!

Andy