have a miprom 21 ac car with the disc brake. have a strange problem, the car will take a call, lift the brake and then just kind of hover at the floor, it may move a little each way, it will do this for 3-5 seconds, and then take off to the next floor, as it comes into level, it will do the same thing, slow down, hover, like it is looking for floor level, dzu and dzd come in, and it will kind of hover slightly back and forth, not more then an 1/4 inch or so, and then finally set the brake at that point it is about an inch or so low on all the floors, I'm thinking that maybe the car is trying to find the learned floor level, maybe position encoder is failing, although it will run full hi speed runs and not fault out , just does the above scenario. thinking of doing a learn run to see if that helps, but thinking about the encoder. any ideas

Go to MSU adjust, Motion Info, 3rd screen back,velocity information. This screen lets you compare the velocity command, the position encoder, and the velocity encoder. run the car on inspection and watch the screen. All 3 should be close to each other.Also check the Zero command parameter. If it is too long, car will hover at the floor when coming into a landing. Check load weighing, or unplug load weighing altogether and run the car.

I'm with John Jay,

If your stability pot (R4) is set to high it may act that way...

Ok. Checked msu info screen jay. All good there. I decided to do a learn run any way. Strange outcome. Car now works fine in the down direction comes in floor level stops and does not do any of the hovering before takeoff or landing
Now only in the up the car comes in alot slower. Hovers just a second or 2 then sets brake. Does not try to relevel. It is about .75 inches low only in up
If i adjust floor level thru tool. I say 2 low and make it 6. Now car comes to floor in up and is just off level a tad. But it is still level in the down. All floor lwvels in up were low. I set them all at 6 low and car is just off level in the up only but down is fine. Just playing with these to see how it would react. It still comes in slower and hovers in up but is close to floor. If i adjust the decel and low level parameters i can get the car to come into floor in up direction without hovering just like the down but the car comes in to hot in down and is a little off level. I did replace position encoder and relearn just to see outcome
The priblem seems to be that car is just not coming into floor in up and down equally. Like a compunding problem. But of course it is a ac car. I did check and adjust load cell and went thru procedure on drive board to see if this was problem. Everything went according to plan in load cell adjustment
Not sure where to go from here. I cant even log on to the ac drive unit with kone tool. It just says logon failed

I wonder what would happen with a full load in the car?

Does this unit have dynamic braking?

Does motion averages say your up and down speeds are the same. if not you can adjust them through Drive adjust, ADC 1 offset I believe is the parameter. A minute change like -.001 or -.003 affects the down I think. Up is not as touchy .005 or something like that. make a change then run the car and watch it come in to the floor. Also in MSU Adjust there is a parameter that may be affecting you. Min Pos Err. dictates how far away from the floor you can be and still set the Brake. Check this first.

Just another thought, it may be that your Vane Readers have moved. 1/4 or 1/2 inch is a big deal.If you put the car at the floor on Inspection from the car top. Your Readers should be equal distance apart on the Vane. If they aren't, set them at every floor and then do a learn run. Also the Readers have to be exactly the proper distance apart. I forget the number offhand. My Brain Cells are waning.

jkh ill check on that dynamic braking circuit. something to think about. thanks
jay, thanks for the input. i did check min pos err, it was the same as the other cars, i found a manual for the ac drive that gives a better description of all the parameters and how to adjust a car from startup. it may help. i was wondering about how to access the drive menus, there is a note on the controller saying drive password is 0000 there is a plug at bottom of drive, is this where i should access this? i was just reading the adjustment manual, and it says get to ready screen and press drive adjust button on tool, i never noticed that button before, so i will check it out. manual does say to adjust the adc1 offsets like you mention, so thanks for the insight. this is the only ac miprom i have had to deal with and have never had to access drive menu, so good learning for me. just to refresh your brain cells, measurement is 12 7/8 :}

I only ever used a company service tool. The world tool should have a drive adjust screen. Unless you need different software for an AC Drive.

i have the Kone hand held tool. went back to the job, checked up and down speeds, the up and down hi speeds are about 15fpm off, slower in the up which is the direction I'm having trouble with. i looked at the motion info screen, and have noticed that when the car comes to floor in up and stalls for a few seconds before setting brake, the commanded speed is 5fpm, but the car does not move. has to be something with drive not being able to make car move in up direction at slow speed. jkh it does have regen resistor, and it is good. cannot get into the drive to adjust the ad1 offsets, there is a plug on the drive for communication, but it will not let me log on. if I'm in the miprom 21 program, and press drive adjust, it just says the routine is not yet implemented. i do have one last hope, i was not paying attention, but when you first power up the unit, i get a hard fault 9, which indicates power supply problem, it then goes away after a minute or so, and then switches to HF 24, which says power up sequence problem, you can then run the car, at which point the HF24 goes away and no further faults. I'm thinking maybe the drive power supply is bad, there is a 20 pin connector, from power supply with no markings as to what is what, power supply board has no markings , and print just says +12,-12,5,24 and does not say which wire is for which. so kind of hard to get a reading. had to go on an emergency call, so i will look into this later. maybe onto something with the power supply. ill let you know

You must have a Baldor or some other type Drive. The SWEO Drive was integrated into the Tool Software. The Baldor and some of the Baldor replacement Drives were not accessible with the tool. You most likely have a drive issue. Can you swap out the Main Control Board with another Unit? They were plug and play as I recall.

There was a keypad display that showed fault codes and such on the Baldor Units. Is it on site? It also was how you changed parameter values.

Drive box says spectron. All allen bradley parts inside
Did figure out that the +12 v power supply is only 10. All others ok
Maybe this is causing drive to not respond corrextly. Will see

I'll send you what I have for that drive...

the Spectron was the 1st AC Drive and proceeded the Digital SWEO Drive, unfortunately very few were installed. Parts may be a problem.

thanks everyone, nice manual jkh, and jk i did find a power supply on eBay for 225. one of the other cars has a power one power supply that was wired to the drive, so either way i will get it replaced and see the outcome. of course ill be on vacation for the next 10 days, so it will have to wait. Kone indicated that they have a upgrade for that drive, has anyone out there upgraded this drive

We only ever installed 1 Duplex on a Collage Campus. We lost the Contract to Schindler. I heard that they had a tough time with those units and replaced the whole Drive with something else.

well replaced the drive power supply with one i found on eBay, thanks jkh, this took care of the hard fault #9 and # 24, unit boots up with no errors now, the unit does run much smoother with the new power supply, however same problem in the up direction, car comes to floor commanded speed is 3fpm, car stalls and sets brake 3 seconds later, car off level. still works great in the down. did a complete msu setup, offsets etc, all went well as per the instructions, same outcome, still can't access drive, i have a level 3 tool, might need level 4 tool, going to have to look around. looks like they have a yaskawa drive upgrade that we could sell customer, going to look into that. will keep you posted

Looking back through some old material, I found a procedure for the drive velocity command calibration. I remember doing this on the two installs we had. Do you have a copy of this procedure? It perfectly describes your problem at the end of the procedure.

When the car stalls an 1" below the floor in the up dirrection and you have a floor command of 3fpm! Is DZU up?