I received a Simplex 2903 9001 with a 9838 on ebay over the summer. Upon testing the unit on my simplex 4010 i noticed the lightplate was causing a short on NAC 1. Ive tried wrapping the wires in electrical tape ive tried replacing the bulb and nothing seems to work. However the short only occurs when a bulb is installed. When the bulb is out the short disappears. Any ideas on what to do?
Well, I don’t know how to help exactly, but I bet I could give some pointers.
- Make sure you have an EOL resistor installed.
- Wire the light in series.
- Have another notification appliance on the circuit.
I hope these helped in a way!
You may need to polarize the light by connecting a diode across the light’s wires. Otherwise the panel sees the light bulb as a direct short.
Try replacing the bulb, the bulb may have an internal short which is not repairable. A diode is more of a 1 way valve for electricity, that may not solve the problem. There are other types of diodes, but the kind used here is the one way kind. Did you get the light plate new or used?
Thanks for reaching out. The light plate was used. What i noticed is the white wire has some discoloration before the socket on it meaning there is heat coming from the socket. It is polarized and ive replaced the bulb twice. I may just get a new socket if i can find some parts since ive tried all of these and nothing seems to work.
Do you have access to a multimeter? If so, check continuity from the positive wire of the plate to the negative with the bulb removed. I would like to rule out an internal short in the bulb socket.
These light circuits aren’t very complex, so there shouldn’t be many reasons why you would get a short.
I do not own a multimeter. If I stumble upon one ill gave it a try.
This is very interesting. Something similar happens with my Gentex and Potter stuff where it causes my panel to show an open circuit for the NAC the devices are connected to. I am getting a 2903 soon and I will see if the same thing happens with my panel.
Some things known to short Simplex panels are “Non polarized” devices and System Sensor MDL modules. The 4010 panel will only detect a short in the “Non alarm” state. Obviously in alarm, current is flowing through the devices, which should not be the case while in standby. The 4010 will cut power to the NAC if shorted. If an incandescent bulb, it is shorted because the filaments are connected internally to allow current to light up the bulb. If it wasn’t shorted, the bulb is dead.
You’ll need a 1N4007 diode on one side of the bulb to prevent current from flowing in standby and then place a 10k 1/2w resistor at the end to clear the open circuit.
One thing to note: Never ever wire notification applianced in series on any Simplex panel! You will blow the NAC and have a very expensive replacement cost!
The only exception was a 4208 panel in the late 60s which originally wired DC notification appliances in series. The later revs got rid of this.
No other Simplex panel is designed to do this!
Yep,
my FX-254RD read them as a short circuit therefore not powering the NAC’s as a fail-safe. Definitely going to get those diodes. Also going to need to do a little research as well.
Thank you for the info on what diodes I need.
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