Fire Lite MS-5UD "ZONE 4 OPEN FAULT"

Hello,

I wanted to know if this would be a simple repair, or if I should just plan on replacing the panel? Also, I found a used panel, “NF-5UD”. Is this a “drop in replacement” for the MS-5UD, or is the software completely different?

Thanks in advance for any help in this matter.

First of all, by the wording in your post and that your email address’s domain points to an IT consulting company, I can take a guess you’re not a fire alarm technician.

If this is a real system installed in a building, STOP AND CALL A FIRE ALARM COMPANY. Not only is this a hazard if you’re not sure what you are doing, but it also becomes a major insurance issue if you get caught doing unlicensed work on a fire alarm system.

Here’s several explanations.
First of all, I have no idea what an “NF-5UD” is-- maybe it is a rebrand of the MS-5UD. If so then it is likely exactly the same but looks different. If the panel needed to be replaced, a new one from Fire-Lite would need to be purchased. The MS-5UD is still in production.
Second, even if it works perfectly fine, NFPA and UL prohibit using used components in a fire system. Only new components are allowed. The reason for this is because used components come from all kinds of random places and you never know what could be wrong with them. Even if it looks fine when you power it up, it could randomly start faulting after a few days due to an intermittent issue in the panel’s internal circuitry.
Lastly, “Zone 4 Open Fault” means that there is a wiring problem in the zone because the panel is not detecting the end of line resistor. The panel is likely fine in this case. A technician would have to trace out the circuit and find the break in the wiring.

But like I said above,
CALL A FIRE ALARM COMPANY AND HAVE THIS LOOKED AT BY A PROFESSIONAL