@Charles- Your idea brought up memories of Sam's Photofacts and Quickfact. Back in the day, they knew more about a TV or radio than the manufacturer did. So, I did a google search to see if there was a nostalgia website. To my amazement Sam's is very much alive: https://www.samswebsite.com/
This is a 240V unit in a 240V country - Australia. There is no fuse, there is an input power filter - discrete - designed for the unit designed to fit in a small available space inside the back cover, the IEC power plug is simply a plug without extra features. the the power wires snake from the input filter through some other components without connecting to anything until they reach the reset switch which is mounted in the middle of the base. From there the 240V wiring goes to the power supply where is connects via a plug which is inside the power supply enclosure, hower the wire length is so short that it is almost impossible to extract the power supply far enough to partially dismantle it to be able to unplug the input connector. Until you remove the power supply it is not possible to see the reset switch which is buried under it. Of course it is not possibleto get to the power supply until the main PCB is removed - it sits across the top of everything with a multitude of small connectors - single in line, dual in line and FPC - fortunately the connectors all appear to be differentwhich made finding where they re-connected a little easier however remembering where the different cables needed to be routed was a different story ........ not to mention the protective plastic cover over the input filter....
Murphy's Law. An important corollary of this immutable Law of Nature is that a device that has been designed to be easy to service, will never need servicing.
This is how you get Murphy to work for you instead of against.
May not be true in all cases but I have plenty of evidence in my field, Consumer Electronics.
Of course, it is possible to overdesign for Serviceability such that the basic reliability of the product suffers. This is well illustrated by connectors.
90% of electronic faults are caused by connectors. On the subject of the Secret Reset Circuit Breaker, it is likely that Safety Regulations won't allow the manufacturer to mention it to the customer. But for Service Manuals ... <deleted 12 page rant>
Uniquity: I've always believed that there's a great business opportunity in the area of appliance manuals. Some of them are atrociously written and impossible to follow. The problem with that business idea, though, is that any company that would publish some of these useless manuals obviously doesn't care in the first place.
Could you disclose brand name and model of this projector, so all his conversation becomes useful; otherwise the whole exercise is pointless, even dishonest if you will, some sort of pointless, theoretical, made up execise with no useful purpose.
@Curmudgeon- No law degree (fortunately). I missed the fact that the projector had a "reset hole" in the housing. So, I now agree with your original comment...if they bothered to provide a hole it should have been identified...or covered over and not identifed. One or the other.
But law degree or not, a successful design project requires taking into account DFx requirements from the beginning. Meeting legal and regulatory requirements for all of the product's market countries often drives design choices.
(I've been "bit" by 240V too....and 115V / 400Hz has an even nastier bite !)
Spoken like an engineer who also has a law degree!!!! And, since the European version (IF there is one!) would no doubt run @ 240 v (nominal), there's all the more reason to label it, so that people don't decide to "investigate" the internals. Getting "bit" by 240 hurts a lot more than 120, of that I can attest.
IF the hole has been included, then NOT indicating its usage is just plain sneaky. In this day & age where we're being pushed into "green" everything, then having to make a trip to the repair center, or similar is wasting precious gasoline. So, my attitude has not changed...... IF you're gonna put a hole in the bottom pan to reset this device, then put a label on it too. That's the proper thing to do, never mind the argument about keeping satisfied customers, etc.
<However, IF they became aware of the need for such a safety overload protector, and had to add it to the BOM, there's no reason why they could not have also added a small stick-on label indicating its presence. To not do so IS, in my opinion, a demonstration of complete unethical behaviour! >
I agree it sounds like the device was added for the US/Canada market. Possibly the original product was designed for 240V markets and 120V required a different type or rating for the protective device.
I don't regard it "unethical" to not label the presence of a resettable device. Line-connected products that can be disassembled must be labeled "No user serviceable parts inside", "Trained service personnel only", etc. Any labeling encouraging disassembly would be a big "Fail" at the testing agency.
A "reset hole" could be provided but that's another big hurdle to approvals. The best technical solution would be to hard-mount the protector so the button is user-accessible. But that probably fails from a cost perspective, especially if most "trips" are caused by actual internal faults that can't be permanently fixed by pushing the button.
The first Tacoma Narrows Bridge was a Washington State suspension bridge that opened in 1940 and spanned the Tacoma Narrows strait of Puget Sound between Tacoma and the Kitsap Peninsula. It opened to traffic on July 1, 1940, and dramatically collapsed into Puget Sound on November 7, just four months after it opened.
Noting that we now live in an era of “confusion and ill-conceived stuff,” Ammunition design studio founder Robert Brunner, speaking at Gigaom Roadmap, said that by adding connectivity to everything and its mother, we aren't necessarily doing ourselves any favors, with many ‘things’ just fine in their unconnected state.
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