So, this isn't about a computer or an internet system, but I've posted "tech" tales beyond that realm that both remained and got more upvotes than down. That said, if you know a better place for this, drop me a line.

I worked for a communications company, that we’ll call Company A. We were on contract with Company B, to maintain their paging system.

Although pagers have been phased out in most places, some hospitals are an exception. This has one chief advantage that it can still work in parts of the building where you might not get a cell phone signal, provided the system is designed properly. Another thing is that it would be almost impossible for any type of spam or scam to get through, and very easy for a (company A) or (company B) technician to block if that ever did happen. In short, that means that it’s really only going to beep/vibrate for things that are work related.

Most of the transmitter racks were on the hospital sites themselves, connected to the backup power systems that held up the hospital’s critical stuff.

Back in the early days of cell phones, these paging systems once had the advantage of being more reliable as well. Unfortunately, (company B) never upgraded to a newer system, relying on 20+ year old technology to still be able to run 24/7. Mind you, the paging system was actively used multiple times a day for routine things, so this wasn’t something that just sits on standby until needed for an emergency.

The system was modular, somewhat like a desktop computer, and designed with field service in mind. Almost anything but the “backplane” board itself and the wiring could be serviced from the front of the rack. That, and the antenna would be on the roof of the building that the system was in. You could usually just unscrew things from the front, at most needing a Philips screwdriver if that (the original screws were thumb screws, but sometimes those got lost and you only had “regular” ones on hand at that particular moment)

The system was made up of 2 different power supplies, the motherboard, the keypad/display module, the amplifier module, and the “forget-me-not” module, whose purpose I forget, so we’ll just call it Module F if I refer to it again. Unlike most systems, the motherboard actually wasn’t the hardest thing to replace despite the necessity of everything connecting to it. The backplane board allowed you to swap out everything else, and it had nothing but connectors on it, specifically so it would be the least likely “module” to have anything go bad, BECAUSE the engineers realized it would be the hardest board to replace if it did go bad.

Both power supplies had the same voltages and current capacities, but one powered the amplifier, the other powered everything else. There were 2 indicator lights on the power supplies, one to indicate that it’s getting input power and it’s switched on, the other would indicate if it detected a fault with itself. Though the latter wasn’t foolproof (i.e. it could be “bad” without the fault light coming on) it DID help when it worked. Since they were the same PSU, you could swap them to see if the symptoms changed.

Most things that required more tech knowledge beyond basic computer servicing involved the antenna or configuring the software with a laptop. Even though it used a serial port, a proper USB adapter and their software design made it still usable with modern laptops, so at least we didn’t have to try and keep 20+ year old laptops working.

The most common things to go bad in the early days were the amplifier, and the power supply that ran it. That, and problems with the antenna wire connections, usually the ones on the roof that were exposed to the weather and such. Those usually resulted in missed pages only in the outskirts of the service area, assuming a preliminary “maintenance alert” didn’t show up first. Usually a total failure was either the motherboard or the “other” power supply that ran everything else. Module F rarely went bad until much later, and even the motherboard was pretty reliable until things started getting really old and rickety.

Unfortunately, that’s when I got hired on. By then, we were a frequent flier to nearly every location that still had these things. But none of the hospitals nor anyone else Company B supported had upgraded to a newer system. The only reason I can think of, was maybe that a new system wouldn’t be compatible with the old pagers and so they’d have to replace all of those?

Anyway, I’m dispatched for my first solo repair trip to Hospital 400. This site had totally gone down with no warning, which sounded like a motherboard or PSU issue. This hospital didn’t have an ER per say, so at least a missed page was less likely to spell disaster here. I just packed spares for everything we had, an antenna power meter, the laptop with the serial adapter and it’s charger, the whole 9 yards. We also had a little stack of paper explaining the command line interface and what you had to type to do certain things or reconfigure stuff.

The front desk staff gave me a temporary access card to get into the back room where the paging system (among other things) was. I scanned the card and, what do you know, it worked the first time they “programmed” it, which is more than can be said for other places I had been. Oh, and the doors swung open automatically, which I thought was cool, and pretty helpful if you had a rolling toolbox or a dolly full of stuff.

I went to the system, and sure enough, the little display is blank and didn’t respond to any key presses. There was a fan running, but it otherwise appeared “brain dead”. Well, replacing the motherboard would mean redoing all the configuration and such, so I turned everything off and started pulling out the power supply first. Ouch! I caught my thumb in the rack! That’s gonna leave a mark. Well, at least I’m at a hospital. So, after correctly placing my fingers this time, I removed the power supply properly without hurting myself any further. Putting the new one in, however, didn’t yield any progress. Okay, so the motherboard was the next natural suspect. I plugged it in and voila! No display, no sign of life other than the fans. How could this be? The keypad/display module had to be unplugged anyway to replace the motherboard, so if that had a loose connection, I would have already fixed it by unplugging it and plugging it back in. Well, I swapped the two power supplies between each other’s slots, in case the “new” one was also bad. No dice.

I’m out of ideas as to why the system wouldn’t boot at all, so I contacted Company B tech support. To their credit, I got a live person. Per their advice, I swapped the amplifier module: Apparently, there was digital 2-way communication between it and the motherboard, and if it were faulty in such a way as to put “garbage” on the communication line upon receiving power, it could prevent the motherboard from booting. That meant another trip out to the company car, seeing how I only had brought a power supply and motherboard.

I started toward the door I came in and was about to push the exit bar when I noticed the sign saying “DO NOT TOUCH DOOR: use sensor on wall”. I looked to the side of the door, and there was only what looked like a blank plate there where an exit button would have been. I waved my hand over it, and of course nothing happened. There was something above the door that looked like a sensor, but practically high-fiving it (without touching it) had no effect. There were also what looked like sensors on the door itself, but waving at them or doing jumping jacks did nothing.

Uh oh. I look around for other exits. There was one behind me, but it looks like I’d have to go clear around the building to get back to the car, and if the back lot was fenced in, I’d really be up a creek without a paddle. I did have my cell phone, but my eyes landed on the land-line phone in the room first. I figured it would be easier to call the front desk from that.

There was no written directory on or near the phone, and no directory on it’s little display. I tried the most obvious 0 for operator. I waited on hold for several minutes. As soon as I got someone, I asked “how do I get out of the back room without the alarm sounding?” and they were confused. I described the room I was in, and it dawned on both of us that I had reached someone in another building. I said “Can you put me through to the front desk at (hospital address) or security, maybe maintenance? I’m not trapped, but I just don’t want to trip the burglar alarm cause there’s signs telling me not to touch the door” “I’m sorry, I don’t know the right extension or who to contact for that” “Okay, never mind, and thanks for trying anyway. This isn’t your fault” and with that, I hung up.

At this point, I was just going to open the door manually and let the alarm sound. If anyone questioned me, I’d point out the process I went through to try and avoid the alarm. Just as I was about to open the door, I heard the card reader on the other side go “beep” and the door swung open. I explained my whole ordeal to the guy coming in, and he pointed out the little hand-wave sensor on the wall about 10 feet behind me, partially obscured by a shelf. Not only that, the sensor didn’t say “exit” or “do X to exit” nor was it the same color as the door or anything attached to it.

After the whole getting “trapped” in the room ordeal then being “rescued” I got back out to the car and got another amplifier module. And a Module F along with another power supply, for good measure. I planned on putting the original motherboard back in so I wouldn’t have to reconfigure everything if the amplifier turned out to be the problem. I put the original motherboard back in, then the “new” amplifier module. I left the first replacement power supply in place, just in case the original one had somehow fried other modules.

Before turning things back on, I put the antenna power meter in series with the transmitter line to the antenna. One might assume an output short circuit would be the only way to damage an amplifier, but for strong transmissions at high frequencies, an open circuit can result in “reflected” power back to the amplifier, which can also damage it as well. Therefore, it’s good practice to check for reflected power if the amplifier fails. (Better systems can detect this and shut themselves down. In fact, this system is supposed to be able to detect this, but just in case it doesn’t, it’s still good practice to check for it anyway)

I turned it on, and the original motherboard booted when I had the “new” amplifier in. So Company B tech support was right on the money. Score one for them. Good news: Reflected power wasn’t nearly high enough to cause any problems. (There is usually a small amount when the connectors are several years old, but it’s only a problem above a certain amount. Radio techs will know what I’m talking about)

So, I left the site for the day, declaring the ticket closed.