It’s inevitable.  Left on your desk is an old PLC card with a yellow post-it note on it that simply says, “Bad Card”.  So you test it out and sure enough something is mysteriously wrong with the electronic guts of this expensive little device.  Your company may have some procedure for failure analysis and replacement parts, but, more often than not, there’s a cabinet or drawer somewhere with a lot of bad parts, plastered with cryptic sticky notes, that you don’t have the heart to throw out.  As those parts get more numerous, precious and costly it makes sense to check into companies that specialize in PLC repair.

PLC Repair Companies

There are quite a few companies whose main business focus is electronics repair including PLC boards.  Some of them are even completely PLC hardware related but most also service drives, DCS equipment and other control devices.  Not only will they repair PLC parts but they also have a large supply of surplus (new in box) and refurbished parts for replacement.  This especially becomes important in older legacy systems.  Even though parts can be upwards of thirty years old they still support repairs on the likes of Allen Bradley PLC-2/PLC-3, Modicon 484/584, Siemens S5/S7 and Texas Instruments 500/505.  PLC repair companies offer the experience, resources and the technical libraries of schematics and manuals that would otherwise be hard to come by.

Am I a Candidate?

Basically any company involved in PLCs can benefit from PLC repair.  Mid-size to large factories are typical candidates but system integrators and resellers also realize the advantages.  The need for tight controls, minimum downtime and cutting costs make PLC repair needful for all sorts of industries from packaging, food processing, pharmaceutical, automotive and so on.

If you work in an older plant you know how robust a PLC can be working year after year.  You also know as a technician that your equipment will eventually fail.  It’s not a matter of “if” but “when” and that’s when you’ll need repair services.  One of the problems is that the cost of upgrading is just not worth it when it comes to factoring in removing the old system, programming the new one, installing hardware, working out the bugs and learning how to use the new system.  Having a reliable repair service ensures that you can keep the system running at minimal cost.

How Much Can I Save?

First of all, it doesn’t cost anything to find out how much the damage will be in dollars.  The majority of the PLC repair companies do not charge anything for estimating a repair cost.  You would only be out the cost of shipping.

Second of all, there are no charges for time and materials.  A typical repair service has a database of parts and their costs.  These companies have been around for awhile and have amassed the knowledge of typical parts that go bad and therefore have a base cost for repairs.

The bottom line is that it should cost you no more the 50% of the price of new.  Greg Carter of Radwell International says, “We call an item ‘Beyond Economical Repair’ when the cost of parts and labor exceed 45% of buying new.  We try to make repair a very attractive option --- 73% of items are turned around in 5 days or less.”  When I asked Willy Williamson of Electrical South about a rule of thumb he said, “Repairs should typically not cost more then 50% of the price of a new example of the same part number.  If you run into instances where you know a new one can be bought for less than the quoted repair price, talk to your sales representative.”

If a part is deemed as un-repairable, as a back up, these companies offer refurbished or surplus parts at significant savings.  Bill Zalot, President of TEK Supply says, “In most cases if a unit is un-repairable for any reason, we are able to provide a replacement for the customer at a price only slightly more than repair cost.”  These surplus or repaired parts are also good avenues to make sure you have a back up on your shelf for emergency situations.

What About Quality?

Of course fixing a part may not be as reliable as buying a brand new one.  The better repair companies though take a great deal of pride in their work and ensure a quality repair.  A good repair company will offer a warranty on the part or even the whole PLC.  It seems the typically warranty runs for one year but they can differ.  It’s important to pay attention to the warranty and compare it to what others are offering.

It’s also worth asking about their testing and verification procedures.  Make sure they have the ability to put the part in a rack to fully exercise it before sending it back to you.  How important is this?  “We go to great lengths to fully exercise the PLCs we repair.  We use test programs to fully exercise the memories and functions of the PLC.  We really don’t want to see it come back as a warranty.  We also prefer to keep our customers coming back to us with more repairs, and good quality is a major contributor to long-lasting relationships”, said Willy Williamson of Electrical South.

But Is My Part Repairable?

If your part was flattened by a forklift or caught fire and warped into an unrecognizable piece of plastic then chances are it’s not repairable.  Bill Zalot at TEK Supply figures that “95% of PLCs and controls are repairable”.  So your expectation should be that it is repairable even if it’s had the “smoke” taken out of it.  

Age can be factor when there’s a component that is no longer available.  Even then a like component can typically be found and a simple re-engineering can bring it back to life.  While certain components of popular devices may not be available it’s rare that these are the cause of the defect.

Conclusion

Everybody wants to cut costs while at the same time being the hero by providing the quick fix that will get your company back online.  PLC repair has been proven over many years to be a viable alternative to replacing with brand new.  With the right company you’ll have quality parts at half the cost.

If you are looking for a repair company then be sure and check out PLCdev’s list of PLC surplus, used, refurbished and repair suppliers. 

We would like to thank TEK Supply Inc., Radwell International Inc. (a.k.a. PLCCenter.com) and Electrical South Inc. for their contributions to this article.