How to convert an early Simplex 4050-80 light plate to 24-VDC!

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wiley209
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Hey, for anyone out there who has an early version of the Simplex 4050-80 light plate designed to run off 125-VAC (typically the kind that had the horn fully recessed into the plate), a friend of mine (CoolSimasGuy on YouTube) showed me a way to make that sort of 4050-80 run off 24-VDC without having to replace the original light socket and circuitry!
When they would be installed on Simplex systems in the early 1970s, they'd use 6S 125-VAC indicator lamps, even if used with DC audible signals (like the Simplex 4041 or 4051.) But all you have to do is replace that 6S bulb with a 24VDC 6-watt E12 bulb from CEC Industries to make the light plate run off DC!
The attachment 4050-80 bulb test 01.jpg is no longer available
The light plate being tested with the new bulb.
4050-80 bulb test 01.jpg
4050-80 bulb test 01.jpg (181.38 KiB) Viewed 871 times
Showing the 4050-80's light circuitry with the new bulb in place.

Here is the pack of bulbs I bought to use with it...
https://www.amazon.com/gp/product/B00JX ... UTF8&psc=1

I hope this is useful to any collectors that run those early 4050-80 light plates! Or if you're getting rid of such an old Simplex 4208 system but want to use the existing alarm signals, then the bulbs on all the light plates can be replaced with these. (But instead many technicians just opt to completely replace the alarm signals with modern electronic horn/strobes, like at my old school.)
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Simplex 4051
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I have a suspicion that it would just be easier for technicians to trash the whole system and put in modern (read: System Sensor) horns in order to just be done with it and move on.
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Simplex 4051 wrote: Mon Mar 09, 2020 11:39 pm I have a suspicion that it would just be easier for technicians to trash the whole system and put in modern (read: System Sensor) horns in order to just be done with it and move on.
Exactly. I never understood it before, but as a fire alarm tech, I fully understand why these replace these systems entirely. A lot of them don't have backup power, or upgrades to buildings, or a faulty panel. I've replaced a lot mainly due to elevator upgrades.
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wiley209
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EdwardsFan wrote: Sun Mar 22, 2020 5:40 pm Exactly. I never understood it before, but as a fire alarm tech, I fully understand why these replace these systems entirely. A lot of them don't have backup power, or upgrades to buildings, or a faulty panel. I've replaced a lot mainly due to elevator upgrades.
Yep, at my first elementary school it was due to a faulty panel, in this case, the old Simplex 4208 starting to fail. Sometimes the signals wouldn't sound in a certain zone, and the system would often go into alarm, even sounding at 4 AM on one occasion before it was replaced. But at least it shows my city's school district considers faulty or malfunctioning fire alarms a top priority on their agendas.
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Simplex 4051
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So it would have been impossible to just replace the part on the system that was breaking down and you would have to replace the whole system right? In certain cases I mean.
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Simplex 4051 wrote: Mon Mar 23, 2020 2:57 am So it would have been impossible to just replace the part on the system that was breaking down and you would have to replace the whole system right? In certain cases I mean.
On such an old fire alarm panel like the Simplex 4208, yes, it would have been impossible, or at least extremely difficult, as obtaining replacement parts for a 40-year-old panel like that can often be impossible, not to mention that the Simplex 4208 is REALLY obsolete these days.
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Simplex 4051
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No I mean could they just upgrade the panel but keep the devices?
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Simplex 4051 wrote: Mon Mar 23, 2020 7:05 pm No I mean could they just upgrade the panel but keep the devices?
In theory it should be possible, but given the old system is basically grandfathered in, it's safe to assume that they're obligated to remove the old NAs and replace them (due to ADA compliance stuff I assume).

But I see where you're coming from, in my country they just replace the old panels and sometimes the activation devices, while keeping the sounders intact.
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Whether only the panel can be replaced is up to the AHJ. Where I live the AHJ allows a service replacement of an old panel with a new one without having to bring the building up to current code. The fire department would much rather have a system with a properly working panel than a system with an unreliable failing panel.

The stipulation is that only the panel is replaced, which can be a problem with a 4208 system. The 4208 could be installed as a DC system or as a 4208AX which was the AC system. The 4208AX normally used series connected AC audible appliances. There are no modern systems that I know of that can support those series AC appliances. That requires the audible appliances be replaced. Typically the NAC also has to be rewired to accommodate the parallel connected audible appliances. If the NAs have to be replaced and the circuits must be rewired, the service replacement of the panel no longer applies.
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Simplex 4051
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Ah I see. Yeah that makes. But what if it was a DC system? If it was DC and not AC could the panel be replaced relatively easy without replacing the horns?
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Simplex 4051 wrote: Thu Mar 26, 2020 6:33 pm Ah I see. Yeah that makes. But what if it was a DC system? If it was DC and not AC could the panel be replaced relatively easy without replacing the horns?
Yes. The panel could be replaced and use the existing parallel DC NAs. The 4208 DC NACs used an end of line diode which would have to be located and replaced. Depending on the replacement panel the EOLRs on the zones my have to be located and replaced. The 4208 zone module used a 3K ohm EOLR. We replaced those panels with other Simplex panels which use 3.3K ohm EOLR using the existing 3K ohm with no issues.
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In most cases that I've done, we've only replaced the panel and left all the devices intact. One case we replaced a conventional system with a fully addressable one, but left the Bells intact. Another case I did do a plant this winter, where we replaced the horns with LED horn/strobes. It's still ongoing kinda, as the age of the plant (from the 60s), has a lot of wiring issues with NAC circuits and some hard to reach horns we can't get to, even with a lyft. I notice if the devices are 24V, they usually keep them. 3rd case did a Bell to horn upgrade, but the reason being was the Bells were 120V. It went through 2 panel upgrades before they finally decided to replace the Bells with Horns. The bells were controlled by a relay that was connected to another relay with 120V on it to ring the Bells.

I worked with a Potter Booster panel that had a cool feature. Instead of going out in the field and replacing EOLs, there was a spot in the panel that you could put a resistor from the old system in, and the booster panel would use that resistor value as the EOL value.
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EdwardsFan wrote: Wed Apr 01, 2020 1:41 am In most cases that I've done, we've only replaced the panel and left all the devices intact. One case we replaced a conventional system with a fully addressable one, but left the Bells intact. Another case I did do a plant this winter, where we replaced the horns with LED horn/strobes. It's still ongoing kinda, as the age of the plant (from the 60s), has a lot of wiring issues with NAC circuits and some hard to reach horns we can't get to, even with a lyft. I notice if the devices are 24V, they usually keep them. 3rd case did a Bell to horn upgrade, but the reason being was the Bells were 120V. It went through 2 panel upgrades before they finally decided to replace the Bells with Horns. The bells were controlled by a relay that was connected to another relay with 120V on it to ring the Bells.

I worked with a Potter Booster panel that had a cool feature. Instead of going out in the field and replacing EOLs, there was a spot in the panel that you could put a resistor from the old system in, and the booster panel would use that resistor value as the EOL value.
Those Potter NAC panels are excellent. Our Siemens dealer has used them before when replacing non-Siemens panels. For example, the middle school I went to had its "frankensystem" (Cerberus Pyrotronics SXL-EX+Fire-Lite MS-5210UD, replacing the original 1977 Standard SET7000) replaced with a Siemens FireFinder XLS in 2018. They used a Potter PSN-106 to run some of the old MS-5210UD's NACs with System Sensor P2Rs and Gentex Commanders in the mobile classrooms. The original horns (Wheelock 34/34Ts, with some Cerberus Pyrotronics MC-S17-Fs added in the late 90s) are also run off of the PSN-106, while the FireFinder XLS runs some new Z-Series signals in renovated areas. All the conventional initiating devices are wired to CDC-4 modules in the FireFinder XLS.
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