S115 Cpu 941

Hi - I have a rack with PSU CPU and a mixture of I/O modules.
The CPU has a fault on board and I am looking for a circuit diagram for the board.

When you say fault do you mean a "Real" hardware fault or one of the leds on the processor is showing error as this could be program or I/O error.

Hi no sure as yet, Ni errror LED's on this CPU red "Stop" LED.
Unable to start PLC either from PG or switch. A bit wierd really as Step5 goes online, try download a bit of code e.g. a simple one liner OB1, but message says something like "failed to transfer - Eprom full" ???, theres no eprom plugged in - only the system one on the main board inside.

On some of the 943/4 processors they were prone to ram chip problems as well as processor, we had a number that you could not load programs to ram, have you tried a cold restart i.e. delete all memory (if I remember you hold retentative switch down then switch from run to stop & then back to run, try it a few times it's years since I used S5 but someone hear will know.

Hi there, oddly enough, after headscratching a bit, I deleted all from PLC, and bingo, up it came. After a while the the thing stopped, and same symptoms. I repeated the exercise, all OK - found leaky 3mf 35v capacitor on board, replaced it and cleaned it out again, and has been running with a smple loop switching all QW,s on and off. I suspect noise may have been setting odd memory bits - just a theory. Been OK for approx 24hrs.