DC Motor Control Issue

Well there are all sorts of different DC motors. I suspect your motor is larger in power than the board was designed to handle.

Picture from http://mrbenbenzftc.en.made-in-china.com/offer/YqQJlKUHVRhP/Sell-DC-Motor.html

It is one of three doors that have been installed at this location 2 work fine and have had no issues. no modifications have been made from the factory. I find it strange that it will work when the relay is in the battery mode(power off) but blows up the min speed trim pot when powered up with no speed selected and no connection is possible to the battery circuit.

The battery is floating, but posibly not the DC supply, which ground might have a potential between the drive's ground and its own negative side, this is destructive, for any components closing the circuit to the ground, like the min speed pot. (motor size doesn't affect the pot's current, that's apparent to the power stage only).

Send a complete schematic and you'll get a lot more help.

Regards

If you have two other doors operating correctly then compare the wiring of your motor to these.

There must be incorrect connections somewhere to cause your problem.

What is your initial set up? direct connection to the battery bypassing the controller?? If so the motor must be good.

Unusual fault a speed trim pot should not be in any part of the circuit which carries large amounts of current.

Some circuit diagrams would help?

Fully correct.

It could even be a defective motor, he could swap in a "good motor" before he blows a new PCB.

Its sad that there are no quick blow fuses to save the electronics from damage.....

Furthermore, why would a pot blow??? Usually it will be a power transistor (or two) that takes the motor current, not a pot......maybe there are serious other problems......

Not enough info for us to be really helpful...as you said!

Not enough info, but it seems crazy that a trim pot blows. You'd need to post a full schematic of the board and the installation to get a reasonable answer.

If everything works on battery, then your DC power supply is probably defective, (or there is a grounding path that is not provided by the battery setup) perhaps generating spikes that cause a zener (or any diode acting like a zener) to conduct, thus causing a short in the control part of the circuit, etc. etc.

With a correctly-sized properly-regulated DC power supply, the operation on battery vs the supply should be the same.

I assume you have the Saino F1900-PLC operator. If this is correct or not, it makes little difference in what I am going to tell you.

If you make ANY alterations to a U.L. listed device, you void the U.L listing. Even if you find a way to force the troublesome situation into operational compliance, the fire label is voided.

I agree with others who have said motor trouble, or signal trouble, or... there is something that is giving the control board some bad data, unexpectedly energized contacts, false force reading...

What does Chase have to say?

[edit] I read again your #2, where you said "I find it strange that it will work when the relay is in the battery mode(power off) but blows up the min speed trim pot when powered up with no speed selected and no connection is possible to the battery circuit." Have you confirmed the supply voltage is correct?

you are correct it is the F1900-PLC and the incoming power is correct to the board. Chase is just as cofused as I am . they had the compleat control board at there factory ran tests on there test bench hooked up to a much smaller door motor got it to operate corectly ,sent it back but the moment it was powered up the small min speed pot blows right out leaving a black hole.... no speed comanded or initilized just power on.. the chase mechanic that serviced it is baffled. he is now sending one of the damaged boards to the board manufactuare to see if they have any ideas. I think it is probaly a ground issue my self but unfortunatly have no drawings of the internal conections only user terminal interface.

You answered "...incoming power is correct to the board."

OK, what about power for the motor? How about to the transformer/filter, in and out? Are the leads from the fire annunciation system dry? Are all of the actuation leads dry (this is sometimes an issue if there is a remote control to operate the door)?

What makes you think it is a ground issue? The entire unit should be 24VDC. (It's been a while since I have seen one, this may not be correct. Can you confirm?)