Simplex 4274-2 Pull Station Wiring Diagram Needed

Hey everyone,

I recently purchased this strange Simplex 4274-2 pull station. It appears that there is a Simplex 4208-style coding wheel on the rear of the device, so I’m not sure if this is just intended to be an electrically-driven coded pull station, or if there really is “more” to it as others have suggested. Either way, at this point I’m not sure which terminals match up to what function on the pull.

I’ve attached several images of the unit below. The tag states that the Wiring Diagram for this unit is # 800-648. To be honest, as long as I’m able to nail down the 120VAC input terminals to run the coding motor (if such an input exists), I should be able to work out the other connections. If anybody can offer me any assistance on how to wire this device, I would greatly appreciate it!

Note: Images have been intentionally left large for clarity.

Years ago a coworker converted some of the information on old products into Windows help files. Here is a Dropbox link to his 4274 coder help page converted to a pdf.

<LINK_TEXT text=“Dropbox - Error … r.pdf?dl=0”>Dropbox - 4274_Code_Transmitter.pdf - Simplify your life</LINK_TEXT>

Excellent, thank you for your help!

Do you have any knowledge of how the reset process for these coders works at the panel end? The instructions at the station indicate that the reset switch should be turned to the off position until the trouble light re-illuminates, at which point the switch can be reset and the key removed. However, the indicator does not re-illuminate and the station remains latched into alarm. I assume the unit is waiting for either a voltage pulse or drop from the panel to reset its relays. Power cycling the whole thing works to clear the unit for now, but only after letting it sit for several minutes.

Maybe contact Simplex? I know we were successful before with Gamewell-FCI regarding the M69, it’s possible we’ll have luck with this. :smiley:

I never worked on a system with these stations so I don’t have any additional information. Also, I don’t have any information on the internal wiring or operation of these stations beyond what is shown in the diagrams. As the document says these were installed on 4246/7 and 4208 systems.

Unlike new panels where the computer chip controls the reset length, the older systems had a switch that could be turned for whatever length required. I don’t think there is anything in the station powered by the zone because the 4246/7 put 120 VAC out to the zone and the 4208 is a 24 VDC zone. Those would be incompatible. It could be some sort of sequence of reset operation between the panel reset and the station reset.

There are cams and micro-switches in there. One disconnects the coders towards the end of line while a coder is running. There must be another that stops the motor when the coding is complete. The reset process has to get the motor back to the start position.

Obviously, I am sort of guessing on how this all works.

In theory, if I’m able to find the means by which the trouble light is allowed to illuminate, given that the reset switch is being held in the off position and the unit is latched in alarm, I should be able to work backwards to find how applying or removing voltage from certain terminals affects the relays in the station.

From observing the device, my understanding is that there is a disk adjacent to the motor that completes one rotation for every four rotations of the code wheel. An indentation on this disk is tracked by two micro-switches, one cutting the motor once a full rotation allows the indentation to reach the switches, with the other providing for the circuit isolation that you mentioned.

There must be a way in which this micro-switch interfaces with a relay within the unit to prevent the coder from restarting until reset. Considering that the motor is allowed to start with this switch in the “kill” position, another relay must be able to bypass this switch in some fashion.

The fact that the station will only reset itself after sitting without power for several minutes adds further confusion, considering that there doesn’t seem to be any components inside capable of tracking time, nor is there any reason for there to be. Perhaps residual magnetism is keeping one of the relays activated for a short time after power is cut.