Miprom Hydro Trouble

I am having an issue with door operation on a circa 1997 Montgomery Miprom hydro. The issue is sporadic door operation. In response to a hall call or car call the doors will do the following:

Open an inch and then close or
Open half way and then close or
Open fully and then close without any dwell time or
Sometimes operate normally for multiple runs

During any of the above mentioned operation, I never see DO7 nor DO10 ever get to 120VAC. The output led for either signal will be off, but I measure 10VAC or so (referenced to ground or L1A). When DO7 is inactive i do see the terminal as high as 55VAC. DO10 never reaches anything above 25VAC.

IF the door open, hall or car call button is held; the doors will open fully. During this failure all other inputs and outputs appear normal.

Others have changed the following in an attempt to resolve the issue:

Power supply card
All input cards
All output cards
Timer board
CPU
Input card back plane
Output card back plane
Relay board
Door operator motor
Mac 104 board (now an ECI replacement board)
Capacitor and transformer beneath operator board
SO cable from operator to Mac detector edge

I am kind of hung up on my output voltages being incorrect. My nudging output (DO4) also never changes state correctly voltage wise. All other inputs and outputs appear correct; input led on 120VAC, led off 10 or so VAC and output led on 10 or so VAC and output led off 120VAC.

Any ideas?

From what you’ve stated, and to your knowledge of what’s been done, maybe time to look at DZ control, or faulty DOL inputs (operator micro switch).

You have eliminated everything except the travel wire from D010/D07, or the micro switch's being in the wrong state. Try dis-connecting the travel wires one at a time and see what happens, Also ring out the micro's with an ohm meter.

I have observed the failure with two meters on the door zone signals, they are rock solid during this failure. Operator micro switches have also been replaced.

Traveling cable wiring checks out ok and micro switches have been replaced.

During more poking around last week I did find the following:

Strange AC voltage readings at output terminals DO4, DO7 and DO10 had me confused. On my meter the reading looked very smooth when auto ranging.........the outputs were reading -140VDC referenced to L1A. Something screwy with the ECI door board. I ordered another ECI board, same result. I spoke with ECI to make sure I had the correct board, the tech support guy suggested swapping L1A and L2A at the operator. Swapping line and neutral cleared up my output voltage issues but I then I had issues on the input side of things. I have an unused 104 board that I will be installing and adjusting Monday.

Outputs should read to ss, as they are ground when in the on state. They should read 120 AC only. Inputs are 120 AC only, when referenced to L1A, or ground. Unless of course you are dealing with the low voltage on the call inputs that they came out with later on. Or you have a Bi-Logic version, which is a little different. Reading -140 VDc is concerning.

try disconnecting the DO4