Firelite ms-9050ud Transformer

Quick Question:

My ms9050ud’s transformer (when left on for a certain amount of time) gets EXTREMELY hot. I don’t know if this is normal or not, and if there is a chance of the fire panel ACTUALLY getting caught on fire, please let me know as soon as possible, as I want it to be a full life-safety system on 24/7.


Are you sure it’s the transformer itself getting hot? Not sure exactly how the power supply works for the MS-9050 but the standalone transformer on the MS-4 does not heat up much at all. Under load it feels a little warm for sure but nothing so hot you couldn’t touch it (not that I recommend you touch it). On the power supply board assembly of a panel like the Silent Knight 5808, there’s a couple of resistors (at least I think that’s what they are) mounted right next to the transformers and they get extremely hot. I looked up the part number and they are designed with ceramic to be heat resistant and that panel ran with no power-related problems.

If it is indeed the transformer itself getting hot, you might want to pull out the multimeter and check the panel’s current draw and/or voltages at the transformer. If all voltage readings seem normal (IIRC, transformer should put out between 28-32VAC but check the manual for exact voltages), and there are no circuits drawing an abnormally large amount of current, it’s possible the transformer is faulty. I believe the transformer is mounted to a dedicated power supply assembly on the MS-9050, so you’d need to buy a new assembly.

If this is a real life-safety system, this forum’s position is that you should call a licensed professional to investigate further to prevent liability issues.

(Sorry I didn’t fully clarify, I’m an enthusiast that just wants to have a full life-safety system in just my house [i.e. Smoke detectors, Pull stations, heat detectors, Notification appliances, etc.] so you don’t have to worry about liability issues or anything of the sort ;D) Ok, so I took off the transformer and looked at the label. It’s a Basler Electric Transformer rated (Primary):120 VAC to (Secondary, or panel input): 36 V. The secondary voltage doesn’t specify whether it’s AC or DC (However, I’m assuming AC). Then I combed through the manual, and nothing came up. I looked through the index, table of contents, and I even used the search tool. I feel so stupid, because I would think that Firelite would include transformer ratings on the manual. I dunno, but the only thing I could find was, and I quote, “Primary power required for the MS-9050UD/C FACP is 120 VAC, 60 Hz, 3.0 amps or 240 VAC, 50Hz, 1.5 amps for the MS-9050UDE.” Nothing in there states the SECONDARY power from the transformer onto the panel board; all it states is the input, or primary, power into the transformer. So, I guess I’m at a loss. The only other thing that’s fishy about the transformer is that it’s not UL Listed, sooooo yeah. When I bought this panel on EBay it only came with a PCB board, transformer and chassis. Maybe the seller replaced the transformer with a non-generic, bootleg one. Anyways, sorry this is a long post, and I’ll include the manual’s link below if you want to take a look yourself. Thank you for all your help!

Firelite ms-9050ud Manual Link:

Also, I took a multimeter reading on the transformer, and it’s definitely AC power. It read 44 Volts! So, that, in my opinion, is definitely bad :cry:

That might not necessarily be a sign of an issue. The unregulated transformer assemblies on a Faraday MPC-2000 control panel I own output around 42VDC. It is up to the power supply cards to regulate this output down to 24VDC.

Ok, thanks for all of your help!

44 Volts might be a little bit high. I’m not entirely sure how the MS-9050 converts AC to DC, typically when a rectifier bridge is used (like on the MS-4), the output voltage is about ~1.1 or ~1.4 times the input voltage (can’t quite remember exactly), but no circuit on that MS-9050 would ever be using more than 36 Volts (this would be the SLC). The secondary voltage on your transformer is AC, all the transformer does is step down the whopping 120V AC from the outlet to a voltage the panel works with. Is it still running exceptionally hot?

I studied the MS-9050 diagrams and it looks like the transformer connects directly to the panel and the actual power supply is right on the board so if you suspect the transformer is faulty it should be relatively simple to replace.

Also regarding that full life-safety system in your house, all legalities of it aside, make sure you do your research and extensive planning for where you’re going to place devices. I have my entire system installed throughout my (unfinished) basement so if I ever wanted (or needed) to take it down or add/remove devices, all wiring is readily accessible and there’s no holes in the walls/ceilings that need to be patched or cut. Definitely start a system small until you’re extremely comfortable with all this stuff.