Hi, everyone.
In this lab, my lab partner and I disassembled a black-and-white video surveillance monitor Panasonic WV-BM1410.
Here’s a link to its operating instructions manual if you are interested in learning more about it: https://www.manualslib.com/manual/117719/Panasonic-Wv-Bm1410.html.
At the beginning, we chose to use two Philips screwdrivers, a pair of pliers, scissors, and a scale for this procedures. This was based on the assumption that we might only be able to dissemble this machine to a certain degree, since this old monitor might contain a cathode ray tube, which won’t be able to be taken apart safely. This assumption was later confirmed.
We began working from the back side of this monitor so that we can take off the outer shell of the machine first (Fig. 1). As shown in the picture, most of the screws for outer panel are positioned in a very visible and accessible way, which means that this component might very likely have been designed to be taken apart for easier maintenance.
Figure 1. Back of the monitor
After the outer shell screws are all taken off, we were able to take the outer shell out by simply popping off from the base panel that supports the cathode ray tube and the PCB, which are the two main components of this machine. As shown in Fig. 2, there are several snap joints on the outer shell. This design justified my speculation that this component is supposed to be easily disassembled. Some other interesting designs in this picture include how this outer shell is actually folded from a sheet metal. More specifically, if you look at the bottom portion of this picture, there are edges folded inward so that the folding shape of shell is confined. With this design, the manufacturing of this component is much easier. Think about this, if one manufactures this thing by simply putting three pieces of sheet metal pieces together with welding. However, this folding method would allow them to simply puncture through a single sheet of metal to have all the holes and vents and then fold as desired to have a 3D shape.
Figure 2. Snap joints on edges of outer shell
Moving forward, we took a closer look at the inside. It seems that the red wire has a special circular plastic rim on it (Figure 3). I think it’s possible that this rim is meant to prevent the red wire from touching the wire bundle close to the end of the cathode ray tube. The exact reason might be that one of them is for power and the other for signal. Therefore, it’s essential to make sure that there’s no interference between these two.
Figure 3. Protective rim on the red wire
Next, we examined the antenna, which seems to be grounded onto the outer edge of the screen (Fig. 4). Besides this connection here, we’ve also noticed other wires going to this edge of screen. Therefore, it’s safe to believe that this might act as a common ground to many components in this machine. After we’ve taken out the antenna by unscrewing the grounded end from the edge of the screen, we noticed that there’s a portion of it having a spring structure (Fig. 5). I think it’s possible that this is designed to facilitate the process of assembling the antenna onto the monitor, since a spring structure can allow a larger freedom of operation by stretching it. As shown in Fig. 6 is an example of how another wire is attached here, probably also for grounding.
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Figure 4. Antenna connection
Figure 5. Spring structure on antenna
Figure 6. Possible grounding location
Then we tried to take the PCB off from the base so that we can take a closer look. However, this process was harder than we expected, since there are many protrusions on the base panel to keep the PCB in place (Fig. 7). Also, you may notice in the picture that there’s also a snap joint to lock the PCB in place. I think this is a very good example of how one component is eventually designed to be able to take apart, but still requires structural rigidity, which led to a more cumbersome experience to take it apart.
Figure 7. PCB assembled onto the base panel
After the PCB is taken off. We noticed that there are many empty slots on it (Fig. 8). I believe those empty slots might be designed to left for future adjustments of the machine. One possibility is that this monitor has other different trims. Therefore, it’s necessary for different components to be added so that different upgrades can be applied. Another possibility is that these are meant for maintenance, which means that more components can be added if the service agent want to bypass certain broken circuits, without taking out the broken parts. This could save the company much expense in follow-up repair services.
Figure 8. PCB with many empty slots
Another interesting design we noticed is that there’s a metal plate blocking the power source with coils from the wires connecting the antenna (Fig. 9). I think it’s possible that this plate is made of nickel-plated or zinc-plated steel, or copper so that these conductive metals can help prevent electromagnetic interference from high-voltage power source. This component not only has screws to keep it place, but also glues. It took us much effort to take it off. Therefore, we believe that it’s possible that this is not meant to be taken off and probably for good reason. Firstly, this component is simply a piece of metal and not much damages can happen to it. Secondly, if it’s not secured tightly onto the PCB, the customer might accidentally remove it and deteriorate functionality of the machine.
Figure 9. Trying to remove the metal plate from PCB
Moving to the cathode ray tube (CRT), though we really wanted to take it apart to have a better look into the functioning mechanism of the monitor, there’s a sign on it that warns us about the potential danger of explosion (Figure 10). Apparently, the glass envelope of the CRT is a sealed vacuum tube, which means that there’s a huge pressure difference from the outside. In other words, there is already a significant mechanical stress on the CRT glass. If the encapsulation is opened, such vacuum would cause the glass to collapse inward violently due to external air pression. One assuring thing is that there’s a safety mechanism for implosion protection. However, such a mechanism means that at least this component may not be well suited for recycling or being reused safely.
Figure 10. Warning sign on CRT
Another interesting design about this monitor overall is that there are many small cartoons on the essential buttons, besides worded instructions (Fig. 11). As you can see are some cartoons of how buttons are pressed down versus unpressed. I think this is a very nice touch and can really help people at that time who are not very familiar with operation of this monitor.
Figure 11. Cartoons on slots for buttons
To sum up, I think this is a very interesting experience and I learned much about what design considerations a streamlined product potentially needs in order to better serve the customer group and facilitate operation of company technicians. I very much hope that in all the future projects, I can truly show my users the care I have for the products and the care I wish for them.
Here’s a picture of how we organized the screws and other assembling components during this take apart lab (Fig. 12).
Here are the links to my worksheets:
https://docs.google.com/document/d/1FGnsfBVBHpXtxAy03zcLwH1TPi9v-vqM/edit?usp=sharing&ouid=118228260040815300372&rtpof=true&sd=true
https://docs.google.com/spreadsheets/d/1GyctPMBHoTUPafKKv-vqWRnGtro6CAtO/edit?usp=sharing&ouid=118228260040815300372&rtpof=true&sd=true
We’ve also cleaned the table top as required (Fig. 13).
