How To Bring An Ancient Door Operator Back To Life

The troubleshooting of this system was mildly interesting, but the effort required to get the electric strike out of the frame ranks this job in the top ten of botched installs by others.


A customer called because the handicapped operator on the inner vestibule doors stopped working. The building was the telephone company, and they had changed owners several times over the years, but the building and personnel had remained pretty much the same.

The setup on the inner vestibule doors was a pair of older motorized operators (no hydraulics). Entry through the inner vestibule door was via a proximity card reader and handicapped button in the vestibule. The door was always locked. A valid credential unlocked the door and pressing the handicapped button actuated the operators.

Egress was either by pushing on the CVR exit devices or pressing a handicapped button on the wall inside the lobby. Pressing the handicapped button released the locks and actuated the door operators.

When I arrived, the handicapped operator would not open the inner vestibule doors. I had to remove the full-length cover from the dual door operator to examine the patient.

The door operator had no radio controls; everything was hard-wired. Judging by date codes and the way wiring was run, this system had been installed in phases, and the operators and the electric strikes were installed during the initial construction of the building or a major renovation of the opening.

It looked like this system was rarely serviced, so it probably had been working pretty well for an extended period and so no resources were directed towards maintenance.

My first idea was that the delay module had died. Since it used a modular wiring connector, it was easy to plug in another one. This didn’t work and I noticed that no LEDs were lit in the module.

A low voltage transformer was mounted to the operator backplate. I metered it and it was not providing voltage. The transformer powered a relay, the delay modules and the electric strikes. So with a bad transformer, the electric strikes could not unlock and no triggers would reach the door operators.

I obtained another transformer, and connected it. Now I could hear the door operators trying to open but the strikes were not unlocking. The interface relay was ancient and the installer had soldered wires to it rather than use a relay module with screw terminals. Four diodes were connected into a full wave bridge, soldered and wrapped with electrical tape. At first glance it looked like a baseball stuck up inside the door operator.

Almost immediately I determined the electric strike was not releasing, and then that the coil was shorted. That explained the blown transformer and why the doors would not unlock.

What was so special about this installation was that the installers must have figured that the strike would last forever, so it was okay to install it so it could not be removed from the header. Apparently they shoe-horned the strike down into the header before the glass transom above the doors was installed. Therefore it would require that the large piece of glass be removed in order to get the strike out to service or replace it. The customer took me up on my suggestion that we cut the face of the aluminum header instead of removing the large piece of glass.

Gaining access to the electric strike was quite a challenge. The original installers were indeed mad scientists. Using the lock body of a Folger Adam strike, they mounted it into the extended header and notched the face so the latches would pass.

Although their one-way installation forced me to perform several hours of labor, I would recommend to Ledger readers to avoid installing things so it is impossible to service them without dismantling the building into which you are installing.

Once I pried the strike assembly out of the frame, it was déja vu all over again. During the late 70s and mid 80s, my company sold Folger-Adam strikes and I was rather adept at stripping them down and putting them back together.

A single coil controlled both latches with a link wire. The coil had cooked after the coil had shorted. The plunger would no longer move, nor could it be removed from the solenoid.

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