Without a tracking generator-equipped spectrum analyzer, I cannot verify Monster's claim of low-loss RF surge suppression. But the HT800G does at least have a fully shielded RF unit instead of the naked-bottom PCBs found in APC's fancier models.
The Mystery PCB
Here's the component side of that small “mystery” PCB. It features one generously-sized 1µF X-cap for EMI filtering connected directly across the load-side metal strips, along with support components for Monster's surge protection buzzer that lets you know when the surge protection either kicked in or failed.
The Main PCB
Soldering on the main board looks a little blobular, similar to most PCBs with large through-hole leads. But it does not appear to have any obvious issues electrons would complain about. If you are wondering what the six extra holes are for, my guess is they serve other products reusing this PCB.
It's looking a little crowded. So crowded, in fact, that extra circuitry has to be relocated to a small daughterboard. In the top-left corner, we have the input choke and status LEDs. Below them are two film caps whose function is unclear. Occupying most of the middle of the board are Monster's two ceramic-encased MOVs with the usual thermal shut-offs in-between. Below and to the left (and along the right edge), we have the relay controlling power-saving and “dual protect” outlets, current-sensing shunts and likely bits of support circuitry.
If you were expecting anything fancy on this little PCB, you might be disappointed. It's only hosts a humble LM324DG quad operational amplifier, likely acting as a comparator for the dual-mode surge protection and detection amplifier for the GreenPower master current sensing.
At The Input
On the left, we have a chunky common-mode choke to filter out high-frequency noise and soften edges on incoming surges to spare other components, such as the MOVs and X2 cap - at least in cases of common-mode events. The 330nF (front) and 680nF (back) film capacitors on the right form capacitive voltage dividers with the remainder of circuitry connected downstream from them. The larger capacitor powers the daughterboard, while the smaller one appears to be powering the relay's circuitry.
On And Off
The HT800G's GreenPower function needs to measure the “Master” device's current to determine whether it is turned on or off, and does so using a pair of metal shunts on the master's neutral side. You can see the master's neutral (covered in fire-resistant fabric near the MOVs) connect to the PCB on one side of the shunts and the normal outlet strips' neutral at the other end. The small potentiometer just below the MOV most likely provides trimming for the GreenPower on/off threshold and is covered in glitter-glue to prevent accidental changes after factory calibration.
The Star Of Monster's Show
These are likely the main selling point for most people – they certainly were for me. I would expect manufacturers of ceramic-encased MOVs to put their brand on display, but these have no visible manufacturer markings on any side. Doing a search for the 20S201X3 part number returns a few hits on Chinese distributors, one of them with a matching pictures lists the manufacturer as Shenzhen Kangtai Song Long Electronics Co., Ltd. The corresponding website was not responding when I tried accessing it, and I was unable to find the specifications anywhere else.
From the part number and distributor descriptions, we can guess the ceramic casings contain three 20mm square MOVs with a varistor voltage of 200V connected in series with one of the four terminals bonded to each internal node.
After the fireproof MOVs, the HT800G's other main attraction is its GreenPower function that switches off controlled outlets when the “Master” device is off. The device responsible for switching those outlets is the blue Goodsky relay, which also performs double-duty as the “dual protection” output disconnect for those outlets.
Behind The Scene
Remember earlier when I wished Monster had simply put five outlets on both sides? It turns out that all of the necessary metal and plastic work is already there; the only missing detail is holes and patented coordinated labels, I suppose, just to keep up with the theme. If someone really wanted the two additional outlets, all they would need to do is drill holes at the correct locations.
All wire connections except mains ground are spot-welded to metal strips, while the ground gets the solder blob treatment. Readers who have been following these tear-downs should be familiar with both connection strip styles by now, but we will still take a look at them next.