Hello all,
I am new to the forum and looking for help with this one. I have a Miprom 21 that keeps giving me a 27 fault when running on inspection. Fault 27 is a performance comparator trip. I have done all the recommended troubleshooting items in the books I can find but I cannot get this car to run properly. On inspection the car will not run unless I disconnect the wiring to the position encoder on the governor. If I leave it connected the car will only run about 18" and fault in either direction. It will recover and try to run again but only about 18". With the position encoder disconnected the car will run up and down the hoist way all day long without fault on inspection. In one manual I found a note that said the car WILL run on inspection with a defective or missing position encoder but this one will only do it if it's missing or disconnected. New motor encoder, new governor encoder, new MSU board, new relay pilot board and ribbon cable from pilot board to MSU board! I have tried changing combinations of channels on the encoder ie. A+ / A- or B+ / B- and nothing I have tried makes a difference. I'm sure I'm leaving some things out that I have done but this has been eating my lunch for a while now and I'm looking for some HELP!! Thanks.

How does it act on automatic? Same 18” then stop? What kind of drive?

I've had problems with the black connector at bottom of the relay pilot board, where the encoder signals come in. Usually I can do a good reseat, but I have had to solder in a newer style connector.

Make sure the Brake is picking. Also what does the error log say when running on automatic. Can also be caused by the car top encoder. Is this a Gearless Machine?

Hi guys. Thanks for your responses.

Indirtwetrust, it did act the same on automatic but i can't try it now as the floor table is gone. The drive is an Allen Bradley 1395 DDC.

Jcjmowery, the new relay pilot board has the new green Phoenix connectors on it.

john jay, the brake is working correctly. can't run on auto. This has a governor encoder instead of the car top encoder. it is a geared basement traction machine.

Does it run long enough to compare the speeds on the Motion Info screen? If motor Encoder speed doesn’t match command speed there may be a drive parameter wrong. Check drive parameters 558 and 609. 12” gov should be 240 ppr, 16” should be 320. Did you do the velocity command adjustment when you put in the new MSU? I think there is a motor RPM adjustment in Motion adjust and make sure Jog is 100.

The lower you set I DRV VEL the longer you will have to compare the speeds before it faults.

Indirtwetrust, i have tried to check screen #3 in Motion info but I don't know how accurate it is. The tool is very slow to process the info. i took a picture of the tool but for some reason I can't attach it. I had Vcmd 47, Vfb 44 & Venc 8. I don't recall checking those params, I will do so. I could not find any info on any adjustment to the MSU board or any of it's pots so no to the velocity command adjustment. Do you the the procedure? Can I get a copy? We do have the correct PPR for the gov. encoder. I will check I DRV VEL and lower it. Thanks much.

Try these, set Min Overspeed Band to maximum. Raise KP Velocity by 10% and see if it runs longer. Check that the PPR in the Drive parameters, and PPR in the MSU are the same. Check that Brake Pick time is longer than Brake Econ time. If this is an analog drive and someone pulled the Main Line switch before shutting down the Miprom, you may have lost all the field programable parameters. Things like the floor table and motor rpm, if this happened you need to check them all.

Here's a pic of the tool.

john jay, I will look for Min Overspeed Band and KP Velocity, I don't recall seeing those before. I have verified the PPR settings. I will try the Brake Pick and Brake Econ settings as well. This is a 1395 Digital drive. I have checked almost every parameter against the job parameter sheets and the car next to this one. I haven't had to reprogram much, maybe 2-3 parameters.

Also check the Timer relays SB1 and P2, one should be around .25 longer than the other. I can't remember for sure which is longer, so if you have another running car you should compare it.

Wow, I’ll trade you a manual for that Kone tool! 😉
Those speeds are way off, is the car moving 50 or 8 fpm before faulting?

You’re sure the PPR is right in Motion Adjust? Could the gov encoder coupling be slipping? Is the Encoder voltage right? What about AC ripple?

Indirtwetrust, Sorry the tool belongs to the customer, government job. It looks like the car is accelerating to about 50 FPM. I don't know if the processor in the tool is able to sample the information fast enough and display it correctly in that short amount of time? Let's say that the Venc the is only 8 FPM according to the controller and I have changed the encoder, relay pilot board, MSU and ribbon cable. I have verified the feedback from the encoder is good with a scope. channels lead and follow each other correctly on a 12 volt scale. I recently swapped the MSU with another running car in the building and it ran another car in inspection with out fault. What am I missing? Do you have the info on adjusting the MSU pots?

Yes, triple checked the PPR on the encoder, New encoder coupling. 12VDC at the encoder and approx 11.9VDC back to the controller on the square wave on the scope. There was noise on the channels coming back but we wired in a BEI filter module in at the controller.

I’m just guessing here now but could the CPU be envolved in reading the Encoder feedback? Have you tried swapping CPUs?

Have you checked over the M switch. A bad aux. contactact can throw a 27 error. What is the error in the Drive Log?

Swapped the CPU also, no change.

Have not checked the aux M contacts as it will run without fault with the gov encoder disconnected. It doesn't log a drive error.

Any chance the tension sheave on the governor rope is bottomed out? How did this start? you say you have no floor table, so something must have happened to lose that.