1746-nr8

cornbread

Lifetime Supporting Member
Join Date
Feb 2007
Location
madison, indiana
Posts
407
I had three 1746-NR8 card go bad in 3 separate controllers. Anyone know of a defect or recall? Getting a bit scared I may need to replace all my NR8 cards proactively.

Any help would be greatly appreciated?
 
Those are SLC 500 cards, maybe they were all pretty old? You might want to get in touch with Rockwell to ask if there are known issues with them. Take a photo of the label on the side of the card that has the exact Series number and other info
 
I've had to replace nearly all my SLC500 4 pt analog in modules. Most were >25 years old. The capacitors on the on board power supplies go bad.
 
How did your 1746-NR8 modules fail? I did not see this post before I started a similar thread on April 30th. Our plant has also experience three 1746-NR8 module failures over the past 2 years in 2 different PLCs.

When our 1746-NR8 boards have failed, they appear to have developed an internal short circuit. As a result, the board appears to be pulling too much DC current and the internal protection on the power supply (1746-P4 in one case and 1746-P2 in the other) trips cutting power to the entire PLC chassis. The high current issue continues to exist if the module is disconnected from its associated RTDs. If the 1746-NR8 module is removed from the chassis, the power supply internal protection will reset (after an off/on power cycle) and provide power normally to the PLC chassis. Two of the failed modules were around 5 years old and the third was closer to 10 years old. I have not seen any similar failures with 1746-NR4 modules and our plant has several in operation that are over 15 years old.

Were your 1746-NR8 failures similar to this or did they fail in another manner?
 
if you are interested, we send our plc components to Teamsesco for repair.
very reasonable and repairs done fairly quick.
based out of Greensboro, NC 1-800-487-3726

I am sure that there are others.

note, they are my repair vendor for plc components only.
if this post violates forum rules, please delete.
james
 
When our 1746-NR8 boards have failed, they appear to have developed an internal short circuit. As a result, the board appears to be pulling too much DC current and the internal protection on the power supply

Almost all the NR8 cards I have replaced were shorted and shut the power supply down. I only remember 1 that had an input fail.
 

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