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SurgeX SA-1810 Tear-Down

Under Pressure

The lone grounding stud in the top cover, as well as all other studs on the bottom, appear to be press-fitted into the sheet metal.

Serving The Tray

Here we have a top-down look at that bottom tray once all of its other wires are unplugged. Between the filter board, main board and the reactor under it, it looks quite well-packed from this angle too.

Filter PCB Top

What is the difference between a generic EMI filter and an “impedance-tolerant” one? Simply the addition of small ferrite bead chokes to form a balanced pi (Π) filter with the other X-class capacitor on the main PCB and a 3.3Ω resistor in series with the load-facing 1µF X capacitor to prevent LC resonance. There are also two 2.2nF Y-class capacitors connected from live and neutral to ground through the top-right mounting hole.

With a dual footprint common-mode choke and doubled-up spade terminals everywhere, I believe it is safe to assume this PCB gets reused through much of SurgeX's product lineup.

Filter PCB Bottom

Check out the simple and straightforward PCB routing; not much imagination is required to see how power makes it way from the inputs to the outputs. The fiberglass board is clear enough that you can even see some of the components' outlines through the PCB.

One Nice Thing About Single-Sided Fiberglass PCBs...

...is that you can back-light them to see most of what is happening on both sides at the same time. This isn't particularly useful for such a simple PCB, but it's still a handy trick to keep in mind for more complex circuits.

Ooh, Shiny!

The soldering looks great except for one little detail: achieving mirror-like solder joints requires either a tightly controlled cooling profile for lead-free solder or the cheaper, simpler low-tech option: lead-based solder. I asked Nicholas and was told SurgeX went lead-free for its international products a while ago, but still use 63Pb/37Sn solder for North American models. There's a plan to go lead-free in the works.

PCB And Reactor Sandwich

The heart and soul of SurgeX's ASM protection is a huge inductor with complementary electronics to take care whatever remaining power surge energy manages to pass through it. High-performance and -endurance surge protection adds a fair amount of complexity compared to basic MOV protection.

In Perspective

How much bigger than conventional MOV protection do you need to go if you want a high-endurance surge protection solution? Well, here is the reactor with its PCB next to a pair of Bourns 20D201K MOVs for comparison. The size and weight differences are not subtle.

Main PCB Top

How much electronics do you need to do a MOV's job when you do not wish to use a sacrificial element? About this much. And the circuitry is only intended to deal with the remainder of surge energy that manages to pass through SurgeX's reactor.

From left to right, we have an AceWin 1µF X2 cap, a discrete bridge made of Vishay P600G diodes, three 390µF 250V Panasonic ED capacitors, a Vishay 1N5404 diode for the peak detection circuitry, a pair of power resistors to discharge the surge suppression caps, air-core inductors to limit current rise rate through the SCRs and the LittleFuse S4025 SCRs with their trigger components.

Main PCB Bottom

The soldering quality looks similar to the filter board. Most modern PCB designers would use copper pours with thermal relief pad connections and 45/90° trace routing. Here, though, SurgeX's PCB engineer decided to forgo copper pours and also use free-hand routing.