On 9/19/2021 12:58 AM, Martin Brown wrote:> Meanwhile many of my neighbours have no TV signal (I'm on satellite).Oh, my! What EVER will they do??? :>
Mathworks Ebook Predictive Maintenance Using MatLab.
Started by ●September 16, 2021
Reply by ●September 19, 20212021-09-19
Reply by ●September 19, 20212021-09-19
On a sunny day (Sun, 19 Sep 2021 08:58:13 +0100) it happened Martin Brown <'''firstname.lastname@example.org> wrote in <email@example.com>:>On 18/09/2021 19:22, Jan Panteltje wrote: >> On a sunny day (Sat, 18 Sep 2021 10:25:44 +0100) it happened Martin Brown >> <'''firstname.lastname@example.org> wrote in <email@example.com>: >> >>> >>> How to do it optimally has been known for around a couple of decades. >>> The old traditional way was to try and avoid all critical in service >>> failures by replacing still working parts before they reached MTBF. >>> >>> We christened it causative maintenance since it was pot luck whether or >>> not the damn mainframe would come back up again after a manufacturers >>> "preventative" maintenance. >> >> In my TV days we would run shifts and if something failed fix it ASAP >> there was also some redundancy in equipment so you could divert operations. > >The magic smoke came out of our local (10th highest structure in the UK) >TV mast last month (literally right out of the top). 1M people without a >TDTV signal and no convincing estimate for a repair time either. > >https://www.bbc.co.uk/news/uk-england-tees-58163612 > >https://www.arqiva.com/news-views/news/update-on-incident-at-bilsdale-mast > >It is very probably scrap now. A new smaller 80m temporary mast is to be >erected nearby when they overcome the legal objections of the farmer. > >Meanwhile many of my neighbours have no TV signal (I'm on satellite).Yes, satellite is a good solution, I can see BBC1,2,3,4 here, ITV and ch4 ch5. Here digital terrestrial TV has un-encrypted local TV for the main Dutch channels. However for reasons (? of selling more subscriptions) Dutch TV on satellite was encrypted last time I looked. There was a fire here many years ago in one of masts: https://en.wikipedia.org/wiki/Zendstation_Smilde Many are on cable here. from a financial POV been on satellite now for 22 years or so, total cost was in today's currency about 100 $? Dish, dish motor, some brackets, LNB, and a 30$ or so sat card for in the PC... record to harddisk. Wrote a lot of software for satellite reception. Much has changed but I still use the same dish and motor. Cable sets you back 50 $ or so a month and has far less stations, but gives you internet, had it for a while, got really bad when ziggo merged with vodafone. Was a program here on TV few days ago how bad and expensive ziggo was for radio... Now I have 4G internet anywhere I go from KPN with an USB dongle at about Euro 31 a month. Radio? I have a good Chinese Tecsun all wave radio.... It even has longwave!
Reply by ●September 20, 20212021-09-20
On Sunday, September 19, 2021 at 2:28:08 AM UTC-4, Flyguy wrote:> On Saturday, September 18, 2021 at 11:23:16 AM UTC-7, Jan Panteltje wrote: > > On a sunny day (Sat, 18 Sep 2021 10:25:44 +0100) it happened Martin Brown > > <'''firstname.lastname@example.org> wrote in <si4bao$1rp4$2...@gioia.aioe.org>: > > > > > >How to do it optimally has been known for around a couple of decades. > > >The old traditional way was to try and avoid all critical in service > > >failures by replacing still working parts before they reached MTBF. > > > > > >We christened it causative maintenance since it was pot luck whether or > > >not the damn mainframe would come back up again after a manufacturers > > >"preventative" maintenance. > > In my TV days we would run shifts and if something failed fix it ASAP > > there was also some redundancy in equipment so you could divert operations. > > One day there was some genius who decided to reduce interruptions in > > the broadcasts to make a 'preventive maintenance' group, and to work those engineers went,,, > > Basically with Ampex quadruplex video recorders that meant taking one apart and putting it back together again. > > The usual things we already did on schedule, like replacing recording heads etc. > > Disassembling and putting back together solid state electronics does not really help, > > 'if it ain't broken do not fix it; > > > > Anyways one machine started to produce little black spots every now and then in the picture, > > It was sidelined, and several engineers had a go. > > One evening I had the late night shift, not much to do, > > everything worked, so I decided to have a look at that machine, > > Took the scope cart, Tek, could detect strong impulses everywhere, was midnight and we went off air (in those days), > > so I wrote in the book for the next shift 'seen pulses everywhere, looks like a shield is lose'. > > My boss, it was his turn next morning, he read that remark and spend the whole day taking the thing apart, no luck. > > Next day it was my shift, took all circuit diagrams, scope and went for it. > > The pulses reminded me of some tacho signal used, > > found the pulse generator and followed its output via a coax cable that send it to an other unit, > > PL259 connector, was sort of lose, screwed it back on tight, problem fixed. > > 10 minutes.... Went back with all the books and scope card and said: Hey guys, let's go get some coffee. > > All the faces there in disbelief.. OK, I said I will show you and reproduce it,.. > > So how did that cable come lose? The preventive maintenance group had forgotten to tighten that PL259 connector. > A lot of this theory depends upon the deterministic nature of systems, namely machines behave in predictable ways that we can detect if we are smart enough. But what if this is not true? What if systems have an unpredictable component that we don't know about? This has happened, for example, in jet engines, which are inspected very regularly with sophisticated instruments. This happened to United flight 232, a DC-10 which had a catastrophic engine failure (https://en.wikipedia.org/wiki/United_Airlines_Flight_232). The cause of the failure was a metallurgical anomaly in a stage 1 fan disk. > > Chaos theory covers this type of situation. If you are blind folded, or walking in a fog, you will be OK most of the time. But, in rare circumstances, you might walk off o, f a cliff. All of the data you could collect prior to the catastrophe will probably indicate that there is nothing to worry about. But that would be wrong, just as it was for Flight 232. Sometimes you just have to shrug and say "It's better than nothing" which it might be. > > While flying I am dealing with similar probabilities. Most of the time it works out fine, but sometimes it doesn't. A couple of years ago a good friend of mine, who was a very experienced pilot, died doing a routine flight maneuver that he had done tens of thousands of times before. Chaos theory caught up to him.DC-10 was a real bad design. If it wasn't uncontained engine failures, it was cargo doors blowing off to the same effect, total loss of hydraulics. https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10#Other_notable_accidents