sci.electronics.repair@googlegroups.com

Google Groups

Look165 <look165@numericable.fr>: Mar 29 02:37PM +0100 I've seen no fuse in mine.   Consider the protection is outside and 16A is enough.   micky a écrit le 29/03/2019 à 14:14 :

Phil Allison <pallison49@gmail.com>: Mar 29 02:30PM -0700 micky wrote:       > I thought all ceramic fuses were slo-blo, but this one is embossed > F12H250 and some webpages say that F means fast-blow????   ** Ceramic fuses come in all types, fast, medium and slo- blow as well as HRC.   HRC = High Rupture Current and are found in some uW ovens.       > Nothing I read decribes why a microwave should need ceramic or slow-blo > (in the power part, not the high voltage part).   ** Ceramic fuses are specified as they do not shatter when heavily overloaded. Slow blow is needed to cope with inrush surges from the transformer, if there is one.     > " If a high voltage comes down the electrical line, the fuse element > will melt.   ** Absurd.   > 220 volt device, so that's less than 7amps normally. So, 10, right? > Unless F12 in F12H250 at the top means 12 amps? " And the home.repair > people told me it did, but the web says F means fast-blow.   ** Single plated wire "F? fuses are in fact rather slow and tolerate brief surges of say 5 times their rating.       .... Phil

Phil Allison <pallison49@gmail.com>: Mar 29 02:48PM -0700 Phil Allison wrote:   *Correction:   ** Single strand, plated wire "F" fuses of 10 amp raring or more are in fact rather slow and tolerate brief surges of say 5 times their rating.       .... Phil

tabbypurr@gmail.com: Mar 29 04:46PM -0700 On Friday, 29 March 2019 13:14:14 UTC, micky wrote:   > people told me it did, but the web says F means fast-blow.   > It's a Crystal, model wp900AP23, but no schematic could I find on the > web and the one taped inside just shows fuse, no details.   If it's F12H250 then you need to fit a 12A F12H250 of the same size & construction type. Fuses are more of a big deal in nukes than other appliances. Don't cut corners on them.     NT

Lucifer <LuciferMorningstar@bigpond.com>: Mar 30 08:58PM +1100 On Fri, 29 Mar 2019 16:14:10 +0300, micky <NONONOmisc07@bigfoot.com> wrote:   >To recap for the scientists: What size fuse to use in a 22V microwave:   The size would be 6 mm if there was such a thing as a 22 volt microwave.

Lucifer <LuciferMorningstar@bigpond.com>: Mar 30 09:00PM +1100 On Fri, 29 Mar 2019 14:37:03 +0100, Look165 <look165@numericable.fr> wrote:   >I've seen no fuse in mine.   >Consider the protection is outside and 16A is enough.   https://en.wikipedia.org/wiki/Usenet_quoting

Lucifer <LuciferMorningstar@bigpond.com>: Mar 30 09:04PM +1100 On Fri, 29 Mar 2019 14:30:10 -0700 (PDT), Phil Allison >> F12H250 and some webpages say that F means fast-blow????   >** Ceramic fuses come in all types, fast, medium and slo- blow as well as HRC.   > HRC = High Rupture Current and are found in some uW ovens.   I had a 5 volt UPS from a Data General mini computer which had a 200 amp HRC fuse.

Martin Gregorie <martin@mydomain.invalid>: Mar 30 12:02PM On Sat, 30 Mar 2019 21:04:14 +1100, Lucifer wrote:   > I had a 5 volt UPS from a Data General mini computer which had a 200 amp > HRC fuse.   Unsurprising: old computers ate power.   The CPU of 1902S mainframe I was sysadmin for in 1972 was entirely solid state (discrete transistors) and with 32 kWords (96kB equivalent) of ferrite core memory. That CPU used 20KW. Add in 6 tape decks, two disk drives, printer, cardreader and a comms multiplexor and the system consumed 40 KW when fully up and running - typical for kit in that era.     -- Martin | martin at Gregorie | gregorie dot org

Stephen Wolstenholme <steve@easynn.com>: Mar 30 01:28PM On Sat, 30 Mar 2019 12:02:20 +0000 (UTC), Martin Gregorie >ferrite core memory. That CPU used 20KW. Add in 6 tape decks, two disk >drives, printer, cardreader and a comms multiplexor and the system >consumed 40 KW when fully up and running - typical for kit in that era.   I never worked on 1902S but I worked on System 4 and the largest 2900's. The current demands were very high but generally low voltage so some engineers would work on live power supplies. Mending the 3 phase mains primary supply in the middle of the night could be dangerous. The secondary output was much lower voltage but high current. We kept an adjustable spanner that had been dropped onto the 5.6V DC supply. It was to remind some engineers of the power involved. The spanner had blown like a fuse. I can't remember the current limit but it was huge!   Steve   -- http://www.npsnn.com

Martin Gregorie <martin@mydomain.invalid>: Mar 30 02:57PM On Sat, 30 Mar 2019 13:28:35 +0000, Stephen Wolstenholme wrote:   > to remind some engineers of the power involved. > The spanner had blown like a fuse. I can't remember the current limit > but it was huge!   No System 4 for me - only 1900, 2903 (the 2900 DFC in a different orange box running microcode to emulate a 1900), and a fair bit of time at the BBC writing systems for their 2900s.   Somebody working in the computer room managed to drop a short crowbar into the BBC UPS when it had its covers off, but caught it before it did any damage - and then had to stand there holding it while the pair of 2960s were shut down and the UPS turned off. Were you there, by any chance?   -- Martin | martin at Gregorie | gregorie dot org

"pfjw@aol.com" <peterwieck33@gmail.com>: Mar 29 11:25AM -0700 Velcro.   https://www.fastenation.com/products/bundling-straps/velcro-r-brand-straps-velstrapr-with-non-slip-neoprene.html   Peter Wieck Melrose Park, PA

jurb6006@gmail.com: Mar 29 11:29AM -0700 >" There are people that don't have any shoes and here you are complaining about what type and length of laces you should get for your boots."   There are people with no feet to put shoes on, and some without legs to put feet on.

jurb6006@gmail.com: Mar 29 11:32AM -0700 Now people who really care about their laces should learn to tie them correctly.   Forget your degree and knowledge, there is a good chance that you are to stupid to know how to tie your shoes properly.   I shit you not. here is a tutorial on the subject;   https://www.youtube.com/watch?v=zAFcV7zuUDA   Hope this helps }:-)>

Jeff Liebermann <jeffl@cruzio.com>: Mar 29 03:11PM -0700 On Fri, 29 Mar 2019 11:25:30 -0700 (PDT), "pfjw@aol.com"   >https://www.fastenation.com/products/bundling-straps/velcro-r-brand-straps-velstrapr-with-non-slip-neoprene.html   >Peter Wieck >Melrose Park, PA   That works fairly well, until the loops becomes clogged with crud or until most of the hooks are broken, or the glued or sewed on edges begin to unravel. Velco claims 20,000 cycles before it becomes unusable. My experience is maybe 1,000 cycles if the straps become dirty or is in some way abused. If you put your shoes on and off once per day, that 365 cycles per year. 2,000 cycles would be about 6 years, which is longer than my "casual" shoes tend to last. If the shoes are subject to UV exposure, nylon UV embrittlement will cause even more broken loops and hooks, thus shortening its useful life even more.   Maintaining Staying Power for Velcro ® Brand Fasteners <https://hookandloop.com/blog/maintaining-staying-power-for-velcro-brand-fasteners/>   US army dumps Velcro for buttons <https://www.telegraph.co.uk/news/worldnews/asia/afghanistan/7831702/Casualty-of-war-US-army-dumps-Velcro-for-buttons.html>     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Allodoxaphobia <trepidation@example.net>: Mar 30 02:21AM On Fri, 29 Mar 2019 11:15:05 -0500, amdx wrote: >> What kind of shoelaces should I use?   >> My shoes still have their original shoelaces, boots really. Now after >> I've worn them for a few years the laces are worn out and I need new ones.   <- big noise dnip ->   > There are people that don't have any shoes and here you are complaining > about what type and length of laces you should get for your boots.   .... in an electronics repair usenet newsgroup.

amdx <nojunk@knology.net>: Mar 29 09:26PM -0500 On 3/29/2019 9:21 PM, Allodoxaphobia wrote:   >> There are people that don't have any shoes and here you are complaining >> about what type and length of laces you should get for your boots.   > .... in an electronics repair usenet newsgroup.   hmm, from my point of view, many people are poor money managers. But very good consumers. My comment was tongue in cheek though.

Fox's Mercantile <jdangus@att.net>: Mar 29 09:53PM -0500 Terry posted this originally a few years back, as a satire of having to read oldschool's postings.   After reading tubeguy's postings I thought it was appropriate.   -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com

Rheilly Phoull <rheilly@bigslong.com>: Mar 30 02:35PM +0800 On 30/03/2019 10:53 am, Fox's Mercantile wrote: > Terry posted this originally a few years back, as a satire of > having to read oldschool's postings.   > After reading tubeguy's postings I thought it was appropriate.   Ahh that explains it, I was wondering about the post now I can see the reasoning!

John-Del <ohger1s@gmail.com>: Mar 30 03:36AM -0700 On Friday, March 29, 2019 at 10:53:58 PM UTC-4, Fox's Mercantile wrote: > Terry posted this originally a few years back, as a satire of > having to read oldschool's postings.   > After reading tubeguy's postings I thought it was appropriate.   Not just oldfool's posts, but there are others here who go through Rube Goldberg lengths to solve a problem that would best be fixed by buying a new one at one half or less the cost.

jurb6006@gmail.com: Mar 29 11:58AM -0700 One thing people didn't seem to notice about points is that you can't just set the gap. The proper gap changes with wear. What you want is for the points to be closed one third of the time.   The number of cylinders matters not. Look at an old time dwell meter, for an 8 cylinder it says so many degrees, but that is at a certain percent of the scale on the meter. For a 6 cylinder the dwell in degrees also hits the same spot on the meter. For a 4 cylinder, with double the degrees of dwell specified STILL needs to be at two thirds, also the same place on the meter scale.   There are a few ways to measure it accurately. The best is with a scope. Sync it to any frequency that lines up with graticule lines and make the bottom part twice as long as the top part.   Another way is to use a resistor and Zener and first take a DVM reading with the points open, just roll the engine to a spot where they are. Read that voltage, should be that of the Zener. Now start the engine and you should read ONE third of that voltage.   You will have to trial and error it to get them really right. Actually GMs had an Allen screw and a window to allow you to set the points with the engine running. The rest you have to try it over a few times. If the "on time" is too short make the gap smaller, if longer make it bigger.   In MOST cases, over the years the lobes wear down on the distributor shaft. What this means is that a smaller gap will be necessary to achieve the correct dwell (closed) time. (duty cycle actually if you want it that way) When this gets too bad, the points are not opening as far and the arcs will wear them out faster. In the old days I noticed people who had to change their points like every couple of months. The coil wasn't shorted, the ballast was fine, there weren't any fouled plugs. It was that the lobes were work down and every time those points opened and made the spark the arc was worse because the contacts wee not pulling back fast enough.   If you have that problem, say if you find the gap is only 0.008" or something and can't get a new distributor shaft then it can be machined. It takes a pretty good machine to do it, but it is not worth programming a CNC for a one off. You can get a guy to do it with NC, OR find an old timer who really knows what he is doing. I am not good enough with that to do it even when I had the machines that might. I am simply not a machinist. you cold maybe find an auto parts place that does their own machine work, they might be able to do it. Some of them though, their machine shop consists of a big belt sander. Remember how they used to mill cylinder heads ?   Not no more. The aluminum heads these days they just blue it up and lay it on a horizontal belt sander and keep on sanding it until all the bluing is gone. A place like that won't be able to do it. You need a GOOD auto machine shop for this. Racing people. Even though they don't use points anymore they should have the skill to do it. you walk in and say "I want to talk to the oldest guy in the place" and then when you get to him "Id you ever redo a distributor shaft, I just can't get one and this thing is eating points, everything else has been checked, the gap is only 0.0XX at 66% dwell.   Something like that. And don't forget, the manufacturer might surprise you and have the shaft in stock for ten bucks.

jurb6006@gmail.com: Mar 29 12:14PM -0700 >"Presumably you know ohms law, just calculate the value to give the 8 volts after starting. "   That will vary with RPM. It does not only because of more sparks per second, but with cam overlap the effective compression ratio changes. More atmosphere in there means a higher dielectric strength so it needs more firing voltage. That will change the current load on the primary and thus if not a solid voltage of course it will vary. the values they chose for the ballast kinda split the difference. That's why when you put a hot cam in a car you also beef up the ignition system to supply a higher voltage. You usually do the cam for more high end and it will still need enough firing voltage up there.   Yes, I am car people and from the old days. At my Uncle's funeral the picture of his car was bigger than the picture of him.   And that is the way he would have wanted it.   We never looked at any book to setup an engine. There was a 1957 Chevy that would pull the front wheels up in second gear, up to 110 MPH, and there was my cousin's 442 that was made into a 642 with three deuces and Edelbrock which ripped the front bolts out of the seat. Can you imagine that ? Your car is rolling down the road and you are laying down and kinda stuck... I would have liked to have a video of that but not actually be there... He lived though, it took a motorcycle to kill him. Well it was his fault I have to admit. And then there was my 1970 Toronado that ripped the asphalt up off the street, and this other car I forgot what it was exactly but I remember I bought it off of a guy named Dwayne but the title was made out to Dawne. I never got the title in my name, I had spare plates all over the place. Why bother ? When I bought it I told him "OK, just sign the title Dawne". LOL My other Uncle was a notary public and he flipped cars, alot of them. If you have more that like 12 in a year you are supposed to have a dealer's license in this state, but they didn't go in his name. People sold him a car and just signed the title, when someone bought it he just put their name on it and notarized it. Everything he touched turned to gold. And that is only a small tip of the iceberg.   So when it comes to old cars, well...

jurb6006@gmail.com: Mar 29 12:16PM -0700 OOPS ! You want the points closed TWO thirds of the time.

jurb6006@gmail.com: Mar 29 12:21PM -0700 >" I bought it off of a guy named Dwayne but the title was made out to Dawne. I never got the title in my name, I had spare plates all over the place. Why bother ? When I bought it I told him "OK, just sign the title Dawne". "   Sorry, I forgot to mention why I mentioned that. It was the car in which I got a ticket in Lakewood, Ohio for flying. Apparently they frown on that.

"pfjw@aol.com" <peterwieck33@gmail.com>: Mar 29 11:29AM -0700 As an aside, I toured the Veolia Steam Plant in Philadelphia, yesterday. This plant has been in continuous operation since it opened in 1909, and is quite a remarkable place. I got to be up-close-and-personal with the equipment, including the steam and gas turbines, the boilers, pumps, controls, switchgear, powerhouse and uplink.   Standing under the main step-up transformer (2,300 VAC to 23,000 VAC) is a truly visceral experience. Once one feels that level of "HUM", one will never mistake 60 for 120 ever again.   Relevance:   60 HZ hum suggests a bad or failing rectifier. 120 HZ hum suggests bad or failing filter caps. 50 & 100 for our Euro and Asian friends.   Amazing amount of mechanical-feedback devices in use in these plants - it seems that VFDs and great many "modern" grid-tie devices are simply not sufficiently reliable or rugged at this scale.   Peter Wieck Melrose Park

You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com.