Mitsubishi FX2N repair -- schematic for PS

I have a FX2N-48MR that has a failed power supply board (FX2N-48/80). Is there any legal source for a circuit schematic for this board? The power supply board also bears the following text: JY331B85901E.

Have you tried to get an external power supply and wire the positive to your inputs and wire the common of each together? I had this same problem with an almost new mitsubishi plc and this solved my problem.

No, not yet. I am guessing that the power supply board produces both 5V for the processor, and 24V for the digital inputs. What voltage should the suggested "external power supply" be?

I believe the board just reduces the 24VDC to the 5VDC for the processor and then just switches the 24VDC through your outputs. It's an easy fix and much cheaper than replacing the PLC. I would use a 24VDC power supply.

Just a thought, but I've had a FX1N power supply go down in the past and it's been a small surface mount fuse on the PS board that was the problem. May be worth a check, this tends to happen when an external power supply is connected to the on board 24v by mistake!

I suspect he will have checked the fuse - as he has the board part number.

However here's a neat trick I'd like to bet none of you have seen before.

When I first came across it in a panel, I remember thinking 'what the .....'

Take the live and neutral completely away from the plc and put your 24V dc supply unit straight on to the 24v and 0v terminals.

The plc works fine negating the onboard (blown) power supply.

After I knew this, I once had a old FXon with a dry joint somewhere on the power side. It would run ok then all the lights would go off. A tap or squeeze of the plc would bring it back to life. I connected a 24V dc supply as described above (removing the 240V ac) and it has worked flawlessly for many years now)

Thank you, Goody and jrayb. I will try powering the FX2N with 24V as suggested whenever I can get back to the workbench.
Cheers

you might try this post it has a small bit of info:
http://translate.google.com/transla...ACGW_enUS397US403&biw=1536&bih=653&prmd=imvns

Thanks Goody,
We had a prox switch short out and blow the 24V, so the PLC looked like it was a gonner.
We disconnected, the L1 Hot, and L2, and connected 24V DC to the bottom, and wallah! it came back to life.
I know, we could have taken apart, and de-soldered the fuse, but this gets us back up and running so much quicker.

My pleasure after all these years....
The afore mentioned Fxon is still chugging away.