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V700 only lasted 2 years in service


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Has anyone had a problem with the V700 having a very short MTBF?  I bought one in 2017 for a project that was mothballed for a couple years, so the v700 sat in its box unopened.

Two years later the project was picked up and the unit was placed into service, in an environmentally controlled computer room with whole room UPS protection. The system ran fine until about 4 months ago when it went completely dead.  it was still drawing power, as the back of the unit was warm, but no display, no Ethernet, and no USB communication. 

Unitronics supports response to my support request was this:

"Thanks for reaching out to Unitronics Support. 

All Unitronics units come with a 2 year warranty. Unitronics does not offer parts or repairs. "

Their only recommendation was to contact sales to purchase a new unit.  

Has anyone else experienced a short MTBF on a unit that was not exposed to a harmful environment? Is it assumed then that the  unit self-degrades while still in the box?

I would have thought that Unitronics would have stood by their products more than this.  Guess not!

 

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I have quite a bit of experience using V700s (and most other products in the Vision line). No field failures in the 4 years or so that I've been using V700s. I suspect you got a one-off bad unit. It happens to the best of them.

 

You might consider trying some possible solutions in one of the "stickied" posts about bricked PLCs. Sometimes they can be resurrected.

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I am familiar with the V700 PLC circuitry and I can say that there are no electrolytic capacitors in the circuit that age even without operation.

During the whole period of using such PLCs, I observed two cases of V700 failure. One due to problems with the external power supply. Another was injured due to the accidental supply of high voltage to the + 24V circuit of the pressure sensor which was connected to the V700 PLC Snap-in I/O. I was able to successfully repair both PLCs.

At the same time, I observed the failure of a completely new V1040 controller on the board which, as a result of improper storage in a damp room (in the off state), oxidized the conductors on the board.

The only thing that comes to mind about your problem is external influences. I know what a closed air-conditioned control room is. In automatic mode, everything is fine. However, when a person goes there - he temporarily turns off all air conditioners and usually forgets to turn them on after maintenance. The result is overheating of the equipment, emergency stop or alarm - switching on the air conditioners and heat shock in the equipment.

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I personally not a fan of Unitfonics but I have a lot of v700 & v570, the ones I have seen fail are mostly due to the wrong manipulation  ( either while installing snap-In modules or ethernet cards,  even hitting the screens) the ones in my plant should have at least 5 years of continuous operation. 

The thing I hate is that snap-in modules are held in place just with those fragile plastic hooks and some wiggling around the machine could make some loose connections. Other than that those PLCs seem to be very rob ust, of 180 units I have seen 1 bad touch screen due to a  dent, and 1 white screen (and I am sure that either someone dropped that plc or  bent the ribbon cable while changing the ethernet card) and 2 dead ethernet cards (I am not 100% sure they are dead, it could be that there were not plugged in In).

 

Are you sure that that plc is damaged?, maybe the battery is dead or some module is disconnected?. There is no message on the screen at all?

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3 hours ago, Fernando Castro said:

The thing I hate is that snap-in modules are held in place just with those fragile plastic hooks

Fernando, you might want to read through all the digression in this topic.  Particularly JohnRs comment which might be useful given your "large" scenario.

cheers, Aus

https://forum.unitronics.com/topic/5793-v200-18-e3xb-not-reading-temperatures-correctly/#comment-22838

 

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10 hours ago, Fernando Castro said:

The thing I hate is that snap-in modules are held in place just with those fragile plastic hooks and some wiggling around the machine could make some loose connections.

Yes, this is a big problem with the Snap-In modules. I always place a bit of duct tape (or similar) to secure the module. In high vibration environments without an unsecured module, the contacts can wear and lose connection. I have always wondered why Unitronics never provisioned for screws. All 4 corners have plenty of room for screws, similar to the ones that hold the back on the V570 (which, by the way, doesn't need screws!).

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6 hours ago, Ausman said:

Fernando, you might want to read through all the digression in this topic.  Particularly JohnRs comment which might be useful given your "large" scenario.

cheers, Aus

https://forum.unitronics.com/topic/5793-v200-18-e3xb-not-reading-temperatures-correctly/#comment-22838

 

I can't believe this is serious... The engineer in me is shameful to fix things with tape, even gaffer tape BUT..... I mean if it works I guess its a solution 🤣😂😅



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22 hours ago, kratmel said:

"I am familiar with the V700 PLC circuitry and I can say that there are no electrolytic capacitors in the circuit that age even without operation.

During the whole period of using such PLCs, I observed two cases of V700 failure. One due to problems with the external power supply. Another was injured due to the accidental supply of high voltage to the + 24V circuit of the pressure sensor which was connected to the V700 PLC Snap-in I/O. I was able to successfully repair both PLCs.

At the same time, I observed the failure of a completely new V1040 controller on the board which, as a result of improper storage in a damp room (in the off state), oxidized the conductors on the board.

The only thing that comes to mind about your problem is external influences. I know what a closed air-conditioned control room is. In automatic mode, everything is fine. However, when a person goes there - he temporarily turns off all air conditioners and usually forgets to turn them on after maintenance. The result is overheating of the equipment, emergency stop or alarm - switching on the air conditioners and heat shock in the equipment."

I have gone through all the un-bricking procedures with no luck.  There has never been any connector or snap on IO changes while powered up and it  was in a secured area where no casual access was permitted. Environmental control is automated, but also monitored and trended. If it were to fail we would be notified immediately.

It looks like I just got stuck with a lemon that i can't turn into lemonade. 🤕

When examining the circuit board I found U601 (RFP 56512) to be too hot to touch. It looks like it may supply power to U500  FPGA (Lattice LFE2-6E 7FN256C-6I) as that IC is also very hot. I removed U601 and then U500 did not get hot, but probably because it now had no voltage source. 

I suppose I could replace both of those ICs and hope it doesn't go beyond them. Would be really helpful to have a schematic, but I seriously doubt that would be available. So at this point I have nothing to lose replacing components as it certainly is not covered under warranty .  It may take a ride in my reflow oven as a last ditch attempt at revival.

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2 hours ago, WSC said:

I could replace both of those ICs

I think you can try to replace only the NCP565ST12 (RFP 56512 marking)  chip. FPGA is programmable and contains the manufacturer's configuration code, and if there are problems with it, then unfortunately replacing it with another unprogrammed one will not give anything.

I am impressed by your research of the hardware and the desire to determine the causes of PLC failure.

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6 hours ago, kratmel said:

I am impressed by your research of the hardware

Kratmel, it looks like you have a new friend in WSC!  Re your corrosion issue, I recall a community heated indoor swimming pool I worked on for many years.  On initial involvement I found many failed sensors in the main space.  Components and junctions eaten off the board by the "corrosive" atmosphere.  The solution was far better air and pool water quality control I implemented, along with very liberal sprays of PCB lacquer on every board in use.  I was very wary of using thick coats of the lacquer in case it upset the circuitry, but it never did and the corrosion issue stopped.  Anything with screw terminals I tried to flood under the terminal blocks so that the lacquer did capillary action everywhere, and the junctions themselves were tweaked every 6 months.  The actual sensing bits for things like co2 and humidity seemed to be made well to survive ok...it was just the rest of the board that was vulnerable.

10 hours ago, Fernando Castro said:

shameful to fix things with tape, even gaffer tape

True enough, so use the screws method!!  It's a bit slower, but better.  Seriously, gaffer is useful stuff.  Although it was primarily aimed at the film/theatre market, which is supposedly how the name gaffer came about, don't forget one use it was immediately picked up for was to hold damaged race car's broken bits roughly in place to let them back on the track!

Crash!--------Pits----------Does it move far more than it's meant to?----------Apply Gaffer tape---------Push it to see how much it still moves--------Apply more tape if needed------Check again-------Smack driver and return car to track.

Now...if I could only tape to the steering wheel the hands of all those drivers who incessantly handle their mobile phone whilst on the road.

@WSC  I'd take notes of install dates etc.  There might be some other factor here not noticed that might cause the failure again in the shorter time.  I also again take note of your mentioning UPS.  Have you checked that everything connected to the controller is powered from the UPS?  Nothing can perhaps be making nasty voltage differences?

cheers, Aus

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