Mark vii fault, plc reboot during wash

[HiPressure]

I'm 2 years new to the at car wash business. Bought a 6 yr old wash (now 8yrs old) with an original Mark vii GT-300 already installed. Until now I've been able to repair everything myself. The Mark vii randomly faults during the wash cycle, every 20 to 30 washes. Sometimes at the beginning of wash, but more often at end of wash, in random locations on the track, sometimes the fault occurs during motion, other times not moving. When the fault occurs, the plc loses total power for 15 to 20 seconds and then comes back to life and sits on the track where the fault occured. There are no error codes recorded because the plc loses power. Has anyone encountered this before?

Any help is appreciated! I've been hunting this ghost for 2 months now, implementing test circuits, etc, with no progress......

 

[MEP001]

There might be a short that's grounding out the power and tripping a self-resetting breaker, might explain why it seems to power down and come back on.

 

[sparkey]

Did you go thorough the panel and try tightening all the connections? Maybe as simple as a loose terminal block or fuse clip. You may also want to try replacing the power supply on the PLC.

 

[lag]

Did you go thorough the panel and try tightening all the connections? Maybe as simple as a loose terminal block or fuse clip. You may also want to try replacing the power supply on the PLC.

I had one of our Allen Bradley plcs that was power cycling last year. Ended up being loose neutral on the main power feed to control panel.

 

[HiPressure]

Thanks for your help. I'm beginning to think my problem is temperature related. The fault occurs more frequently on warm days. Have you ever had a plc power cycle due to high temperature in the cabinet? I'm beginning to think its the plc internal power supply. Its supposed to have a 24dc output of 460mA, I tried a 250mA fuse on the plc 24dc output and it hasn't blown, which leads me to think its the power supply itself being aggravated by warmer temps. I've tightened all connections, inserted fuses on many sensor inputs. I'm about to sell a Mark vii dirt cheap, lol

 

[HiPressure]

Well the resetting problem seems to have been corrected for the time being. I don't think I have found the root cause yet. I installed 2 extra fans in the cabinet that houses the PLC on the gantry. With additional airflow in the cabinet the machine has not reset since.