Citizen A20 dual check safety, safe test over time alarms

**hodaken** · 10-01-2021, 08:22 AM

Hey all,

I have a Citizen A20 that will randomly throw up the following alarm when first powering up and they will not clear....Sure hope someone can help !!!

OT0501 (X1) - OVERTRAVEL (SOFT 1)
SV0488 SAFE TEST OVER TIME
SV1068 DUAL CHECK SAFETY ALARM
EX1000 EMERGENCY BUTTON PUSHED

So far i have checked all the door switches and all the e-stops... all seem to be working...ANY IDEAS ?!?!?!?!?!

THANKS !!!

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**oetkbyentc** · 10-01-2021, 09:40 AM

The 488 and 1068 alarms relate to the MCC off test. Parameter 1946 establishes the time limit.
The EX1000 in conjunction with those alarms is concerning as the MCC contactor should not be tested if in emergency stop. But that also depends on the timing of when the listed alarms are displayed.

Use caution in changing parameters related to dual check.

**hodaken** · 10-01-2021, 10:22 AM

The alarms occurred in the reverse order listed in my post. I checked the function of the e-stop, and it is working. To my knowledge, there is only the one on the machine. There are two on the barfeed, but the CNC hasn't even sent power to the barfeed at this point, so i doubt they could be at fault. Any ideas what else could be sending a bad signal? Feel free to break it down kindergarten style, because this is an area of the machine I am not familiar with at all.

THANKS!!

**zavateandu** · 10-01-2021, 12:40 PM

what type of Fanuc is?
what is the status of the G8.4 or X8.4?
The barfeeder ,een it has no power,must be a short between the 2 pns to bypass the emergency and alos all the hard limit switches from the axis are also in the emergency circuit so when an emergency is on do not look only for the emergency psuh button,can be more on the circuit.

**rcs60** · 10-01-2021, 05:05 PM

check for a short in the 24 volt system
most likely in the knock out overload sensor
also check the coolant low level sensor if it's not the knock out sensor
there is also a 1 amp fuse on the small circuit board left side of the electrical panel

**hodaken** · 10-04-2021, 01:33 PM

Fanuc series 32 I. Coolant level sensors is working, prox switches for knockout are working, this machine appears to not have a knock out overload sensor... we check the 1amp fuse every time...always good. And to clarify, this happens randomly and sometimes you can turn it off and right back on, and sometimes you can do it 50 times before it finally comes on with no changes to anything.....definitely pulling my hair out !!!!!!

**zavateandu** · 10-04-2021, 02:02 PM

there is a menu for dual check safety inputs/outputs
when alarm occurs you should check that page and see what signal is not on ,the left and right colums should show the same bits,if one is not the same like other colums,start from that input/output value

**hodaken** · 10-14-2021, 03:21 PM

That is good info!! Thanks! Any idea where i can find this menu?

**oetkbyentc** · 10-14-2021, 04:44 PM

Under "SYSTEM". Press the chapter key until you see "DUAL CHECK"

**hodaken** · 10-15-2021, 10:33 AM

Citizen A20 dual check safety, safe test over time alarms-cross-check-data-c19-jpg

So, i believe i found the menu. (pic attached). As of right now the machine is powered up, and the only one on the list that is showing anything odd is X0008. Bit 7 is different, and bit 6 is bouncing back and forth. Does this mean anything to anyone?

THANKS!!!

**zavateandu** · 10-19-2021, 01:20 AM

look in the electric diagram to what is assigned X8.7 but i am guessing is the door keylock

**hodaken** · 02-09-2022, 10:03 AM

So... I'm back to trying to solve this problem again...we had the machine up for a couple days, turning it on and off with no problems. Then out of the blue I now have the safety check alarms again, and it will not fully fire up. I did find X8.6 in the ladder showing a problem as well...however, I'm not familiar with ladder symbols so I'm having trouble tracking down a solution. The other problem is that according to the machine manual, X8.6 is a spare so I have no idea what it is connected to....I'm attaching three pics of the locations in the ladder where I found something strange. In all pics, the X8.6 is flashing. I really hope you guys can help!!!