Mitsubishi fx1n-14mr and E100 display power fluctuating

[DAXI]

Hello and good day

I have a Mitsubishi fx1n-14mr PLC controlling a band saw. The PLC is connected via a DB925 - MD8M cable to a Beijer/mitsubitshi E100 HMI for communications and as a power supply via RS-422.

When powered on the display on the E100 panel fluctuating, i.e. the screen turns on and off repeatedly. If the main switch is then switched off, then on again the screens seems to stay on and the machine operates normally. The PLC has a built in AC/DC power supply and I suspect that is may be the problem. Is is possible to switch out the AC/DC module?

To make sure that the E100 panel is not the problem I want to connect a 5V external supply to the port located on the back. Is it safe to have the RS-422 and the 5V external supply connected simultaneously?

Edited October 25, 2022 by DAXI

[DAXI]

[JDennis]

Your power supply may be overloaded or failing.  I ran into this when installing a new camera system in a machine.  Cold start and the machine 24v psu would  power cycle repeatedly.  If you powered the camera on after the rest of the machine, no problem.  Our machine builders had used a psu with half the capacity that had been spec'ed.

[DAXI]

13 hours ago, JDennis said:

Your power supply may be overloaded or failing.  I ran into this when installing a new camera system in a machine.  Cold start and the machine 24v psu would  power cycle repeatedly.  If you powered the camera on after the rest of the machine, no problem.  Our machine builders had used a psu with half the capacity that had been spec'ed.

Thank you for your reply. It does seem that the PSU is failing. But the problem is that the PSU is built into the PLC. Do you know if is is replaceable, or whether it is possible to replace some capacitors on the PLC's PCB? 

[VeeB]

Try to supply the 5VDC directly to the E100 HMI to check if this is improving the situation

 

Edited October 28, 2022 by VeeB
Better advise

[d4rkm4n]

I have had an issue with FX5U before. The PLC wont power on.

I was told by our contractor, the PSU can be repair (change electronic part).

But luckily, the PLC power back on after we dismantle all the part and do air spray cleaning. 

[Goghie]

Nobody should use PLC as PSU. Nobody needs to be that cheap.

Infact that old PLC has quite good PSU but it is with very limited power. 

Both products are very old. I had quite few Bejier's HMIs failing in last few years in similar manner as you described, and I never had FX1N failed.

[Ron_S]

Yep, The old E series HMI's are starting to fail regularly now. But some are very old in electronic terms and have been brilliant workhorses.

[Goghie]

12 hours ago, Ron_S said:

Yep, The old E series HMI's are starting to fail regularly now. But some are very old in electronic terms and have been brilliant workhorses.

Exactly.

[DAXI]

On 10/28/2022 at 10:40 AM, VeeB said:

Try to supply the 5VDC directly to the E100 HMI to check if this is improving the situation

 

I did try connecting an external 5V supply and  the screen seems to be fine. I am worried about connecting both the external PSU and the existing serial/psu cable at the same time. The external PSU and the internal PSU of the PLC don't have common ground. Would that be required?

[Goghie]

It would be recommended.