Fixing broken “springs” on FirmTek trays

After a couple of years of use, the “spring” in the catch lock of the Firmtek trays gives out, and you have to manually push it up to engage the latch.

(See trays here:

I asked, and they will not sell replacement parts, nor will they fix the tray if it’s over 1 year old.

So, I tore it apart myself.  Not hard to do. (Please read all instructions first, before proceeding.)

0) Basically, we’re going to replace the “spring” with some spongy packing foam.

1) remove the three screws that hold the plastic front-piece on the metal tray.

2) slide the front-piece off carefully, observing the light-guides for replacement.

3) the lock/slide mechanism is fit into place and held there by its sides, which snap over small nubs. To release the lock-piece, use two small screwdrivers,(or toothpicks, whatever…) one on each side, to pry the side pieces away from the container, just enough to allow them to pass over the nubs.  The lock-piece pulls straight out.

4) you’ll see that the “spring” is really (in an example of poor engineering design) just two pieces of plastic mold, and that over time, they have weakened where they meet the main body.

5) snap off these two pieces.

6) In their place, insert some scrap of springy packing foam, or a bit of sponge, or something similar which can be compressed and then bounces back. You’ll have to cut it to size, and jam in enough to make sure you can both compress the unit, and have it spring back. This will take a bit of experimenting to determine the correct amount of foam, since various foams have different compressions. The foam goes where the “springs” were, and pushes up against the bottom of the lock.

7) Slide the lock-piece back into place, using one of your screwdrivers to ensure that the foam stays properly placed beneath the metal lock.

Test the resulting springiness and mechanism.

9) Observing the light-guides, replace the assembled front-piece and the three screws that held it in place.

The result depends on the foam, and your skill at finding the correct amount used to replace the “lever-springs.”

The next time I do this, I’ll take photos and post them here. Meanwhile, I hope this explanation will suffice. It should be pretty obvious once you get going.


On UPS (Uninterruptible Power Supply)

First, there are several types, but I’ll point out that they fall into those that produce a “pure sine wave”, and those that produce a “stepped approximation of/to a sine wave.”

You pay more for the former, and it’s easier on your equipment. In fact, some of the newer power supplies (APFC) in computers will not work with the “stepped approximation” type.

If you are using it with high-end audio equipment, I strongly recommend the pure sine wave” UPS. (CyberPower makes fine units at reasonable prices.)

That said, here’s something I’ve apparently learned over the past few days. (“Apparently,” because it’s anecdotal…)

It appears to me that UPS’s which have some way of indicating the state of the battery charge, may not truly be indicating it.

One of my APC units showed a full charge, which should run my equipment for 20+ minutes. However, a practical test showed that it only ran for 4 minutes. When I completely discharged the batteries (using an incandescent bulb, which I didn’t own, and had to run out and buy one) and then recharged the unit, it (still showed) a full charge, but this time, when I tested it, said it would run for 17 minutes.

Next, I got my new UPS, which, upon removing it from the box, showed the batteries at 100% charge… and the printed caution to charge the batteries for 8 hours before using (which I’m doing now.)

Now I can’t verify that the batteries in the new unit were not fully charged, but that would be most unusual for a new, unopened device.

So I’m left with the anecdotal “evidence” that it appears that a LCD unit can provide false information about the true state of the batteries, just as older battery testers did, when they failed to run the test under some built-in load.

Why say this?  Because if your UPS isn’t providing the run time you think it should, let me suggest that my experience says:

Run down the unit using a 100 watt light-bulb*, and recharge it for 8 hours (ie overnight) and see if things have not improved. I’m not swearing they will, since I don’t know the state of your unit, or its batteries, but it’s worth a go.

*Why not use something else? Because the bulb will drain the batteries to a lower level that something with higher wattage (before the self-protection on the unit cuts off all power.)  For reference, my 100 watt bulb actually drew 85 watts, and took 74 minutes to drain my 1300VA unit.