Simplex 4005 Help

I have recently purchased a Simplex 4005 and when I installed the panel, various troubles showed up. The panel came with 2 idc cards and one Nac/relay card. For the signals I had a 2901-9838 with a strobe plate and a simplex 4051 on a simplex 4050-80 light plate. I placed a 10k resistor behind the strobe plate and the horns due to the fact that I had the strobe running separately from the 9838 and I got those two nac troubles. For the idcs I have two simplex 9806 test switches along with a simplex 4051-21 and a simplex 2099-9754 on separate zones also with 10k resistors behind them and got those troubles. When I set the 9754 into alarm the trouble goes away for that zone and when I reset the pull station it goes back into a trouble. Can anyone please give me some guidance on to what I can do to make the troubles go away.

Thanks, Ryan

I can’t say for sure this is the only issue because I don’t know the 4005s EOL values (never worked on one in the field), but the 4050-80 requires a polarization diode to be properly supervised. The newer lights came with these built in.

I was thinking the same thing with the diode, but I’m not 100% clear on the troubles that the OP is getting. Are you getting both a NAC trouble and a zone trouble?

Btw, here are the resistor values according to the manual.

6.8 kΩ, 1/2W, End-of-Line Resistor Harness for standard IDCs; (ref. 733-886)

3.3 kΩ, 1 W, End-of-Line Resistor Harness for high current IDCs; (ref. 733-893)

10 kΩ, 1/2 W, End-of-Line Resistor Harness for NACs; (ref. 733-894)

2.2 kΩ, 1/2 W, End-of-Line Resistor Harness for 8 Pt I/O input mode; (ref. 733-892)

1.2 kΩ, 1 W, End-of-Line Resistor Harness for N.O. tamper switch monitoring; (ref. 733-891)

Looks like OP needs new IDC resistors if he’s using 10K’s on the IDC. NAC trouble is probably needing a diode.

I am getting both nac and idc troubles. But like you said I am using the wrong type of resistor for the idcs. But I am using the correct 10k resistor though. The 2 nacs I’m not using on that card aren’t giving me a trouble which I find really strange.

The correct resistors should clear the IDC troubles. For more information about the NAC troubles, use the ACK button to bring a NAC trouble into the display. Then press the right arrow key to bring up more information about the trouble. If it shows a SHORT condition that 4050-80 may need a supervision diode added. Other reasons could be a device wired into the circuit backwards or a bad device.

The two NACs not showing trouble, do they have 10K resistors connected? If not they could be programmed as unsupervised AUX relays. A clue on that is the relays are offset a little so do not line up with the NAC relays.

The two not showing a trouble do have 10k added. I looked into the horns that are showing me a trouble it does say “short” and there is a diode behind it so I’m gonna go play around with it and see if I get anywhere. The strobe plate that is showing a trouble it says “open”

OK, the circuits with a 10K at the panel should show no trouble. You will have to investigate the circuit showing short. Check that the devices are connected with proper polarity and that all the devices are polarized. The circuit showing open is one of two issues usually. Either the circuit is not complete to the resistor or it could be the fuse for that circuit is blown. The panel can be tested by disconnecting the field wires and connecting a 10K at the panel. If the circuit clears the trouble the problem is in the field wiring or devices.

I’ve gotten rid of the two troubles for the horns and the strobe plate. The panel isn’t outputting the horn nac so like you said it might be the fuse to it. I’m gonna go investigate that fuse.

I checked the fuse and their was nothing wrong with it…any idea as to why it won’t output a signal?

I got the trouble back when the diode was attached to the horn nac and it’s saying that there is a short with the diode attached.

I figured the fuse would be good because it is in the supervised part of the NAC. If the fuse blows the circuit will show an OPEN trouble.

On the circuit that is not causing horns to sound, has the lack of output been determined with a voltmeter or that the horns aren’t working? Possibilities are that the relay that provides the power to the circuit is not closing the circuit or there is a burned foil on the circuit board. Checking the circuit in alarm with a voltmeter will show if power is being supplied to the circuit. You could move the wires to one of the spare circuits and test.

Let’s be sure the diode, if needed, is being placed in the correct place. The mention of adding a diode is for the lamp plate that may not have one. Those older lamp plates were simply powered through a pulsing relay on a circuit that was not supervised. In later years the code changed and lamps or strobes had to be supervised.

Below are some drawings of a generic NAC in standby and alarm conditions. They also show that the diodes are part of the appliances and in series with the working part of the horn or lamp. The drawings should show you how this works.

I have determined that the nac isn’t supplying power with a voltmeter.

OK. Should be one of two conditions.

  1. The supervision voltage turns off but the alarm voltage does not turn on?
  2. The circuit just sits there with the supervision voltage still present?

I believe that the alarm voltage just doesn’t turn on

That doesn’t quite answer the questions I asked.

Have you tried to turn the circuit on manually from the CONTROL/VIEW POINTS menu item. The circuit can be forced on there.


With the system in alarm have you gone to the CONTROL/VIEW POINTS menu item to view the condition of the circuit? It should show ON/CODING or OFF.

This information could tell me a lot about what is happening. Since this is not a new panel there could be programming in it that controls the NAC you are attempting to use for some non general alarm function.

The horn nac says “coding” and the strobe plate isn’t flashing and says “on”

OK. You have determined with a voltmeter that the horn NAC is not supplying signal power. Test one of the spare circuits that has a 10K resistor connected with your voltmeter. With the panel in standby mode there should be supervision polarity present. When the panel is put into alarm the polarity on the meter should switch to alarm mode polarity. If it does move your horn circuit wires to that circuit. Then test the horns.

Is the “strobe plate” you are referring to is the 4050-80?

No it’s a 4903-9101 strobe plate

OK. Have you verified that the circuit the 4903-9101 is connected to is putting out signal power voltage in alarm with the voltmeter?

Are there any troubles on the panel you have not mentioned?

There isn’t any voltage going to the strobe plate or horn nac whatsoever. I’m guessing that the panel isn’t outputting power to the horn nac because of the short that it’s detecting