Goody
Member
Do Allen Bradley try to infuriate you at every turn?
I usually have nothing to do with AB. I rarely come across their PLC’s and I don’t have any of their software. In fact all I know about AB PLC’s has been learned here!
But today I came across an ancient model (SLC 150) running a guillotine. I am sure this is a very old plc as the customer told me he had had the machine for about 20 years.
An output for a solenoid was being erratic and another output had blown a long time ago – could I repair it?
Now at first I was pleased, the terminal blocks just unscrewed and it was 2 minutes work to take it away to my workshop for repair.
Getting down to the relay outputs was something else!!
Every screw, nut and bolt was glued in tight and I mean immovable. There was a massive heat-sink that formed most of the back of the plc but it also wound its way through the pcb back and front with numerous components screwed to it.
The pcb’s were attached together by a flimsy flat ribbon cable that looked like it might break at any point and this also was immovable. I had to work on it in concertina style – gently turning the flailing cards back and forth to unsolder, solder and re-solder.
I had about a hundred separate parts on my bench to refit.
Putting it back together was a nightmare as all the holes had skewed slightly and of course the usual trick happened (to those that repair things)
an important component fell from my grasp, hit my foot and shot off to the black hole that is ‘secret component heaven.’
I am sure you all at one point or other have had this happen; the phrase ‘ where the **** did that go’ is common in these circumstances.
Needless to say, I got all together again, fitted and working and this is just a post to share the anguish and terror we all sometimes go through.
But, I have repaired many models of plc before as output relays are common things that blow.
Usually the output card is nice and accessible, in fact I don’t know of a brand that isn’t.
I hope that later models of AB (especially the brick type) have addressed this jungle of wires and components or do they make it very awkward on purpose?
I usually have nothing to do with AB. I rarely come across their PLC’s and I don’t have any of their software. In fact all I know about AB PLC’s has been learned here!
But today I came across an ancient model (SLC 150) running a guillotine. I am sure this is a very old plc as the customer told me he had had the machine for about 20 years.
An output for a solenoid was being erratic and another output had blown a long time ago – could I repair it?
Now at first I was pleased, the terminal blocks just unscrewed and it was 2 minutes work to take it away to my workshop for repair.
Getting down to the relay outputs was something else!!
Every screw, nut and bolt was glued in tight and I mean immovable. There was a massive heat-sink that formed most of the back of the plc but it also wound its way through the pcb back and front with numerous components screwed to it.
The pcb’s were attached together by a flimsy flat ribbon cable that looked like it might break at any point and this also was immovable. I had to work on it in concertina style – gently turning the flailing cards back and forth to unsolder, solder and re-solder.
I had about a hundred separate parts on my bench to refit.
Putting it back together was a nightmare as all the holes had skewed slightly and of course the usual trick happened (to those that repair things)
an important component fell from my grasp, hit my foot and shot off to the black hole that is ‘secret component heaven.’
I am sure you all at one point or other have had this happen; the phrase ‘ where the **** did that go’ is common in these circumstances.
Needless to say, I got all together again, fitted and working and this is just a post to share the anguish and terror we all sometimes go through.
But, I have repaired many models of plc before as output relays are common things that blow.
Usually the output card is nice and accessible, in fact I don’t know of a brand that isn’t.
I hope that later models of AB (especially the brick type) have addressed this jungle of wires and components or do they make it very awkward on purpose?