- SS Relay causing failure of induction motors? - 2 Updates
- AC Power Surge Protection? - 8 Updates
- Can you provide a diagram on how to thread the rubber belts for the tape decks - 1 Update
- National VCR question - 2 Updates
- Crawford 41A3039 garage door opener - 3 Updates
| Deane Williams <pyroartist.dw@gmail.com>: May 31 07:35AM -0700 I have installed a thermostat in my garage to control a fan placed on a shelf in front of the peak vent. The thermostat box has a 6V AA battery pack which switches control voltage to SS relay near the fan. The relay says "Silicon Power Cube" on it and is rated for 240V and 3A. I am using it on 120VAC. The control voltage is specified at 3 to 32 VDC. This system works perfectly. I have been using common 20 inch box fans. The problem is they only last a year or so and then they just stop working. Sometimes they fail over the winter when they never run. I have tried to troubleshoot the fans but can't find out why they have failed. The capacitors on the motor measure the correct value. I suspect there is something in the SS relay that is causing them to fail but I have no idea how. Are SS relays compatible with induction motors? I am on my fourth fan in about 5 years now and these fans usually last forever. Thanks for any ideas. Soartech |
| M Philbrook <jamie_ka1lpa@charter.net>: May 31 11:17AM -0400 In article <364ff67b-95e1-4156-8917-0181f1274d30@googlegroups.com>, pyroartist.dw@gmail.com says... > I have installed a thermostat in my garage to control a fan placed on a shelf in front of the peak vent. The thermostat box has a 6V AA battery pack which switches control voltage to SS relay near the fan. The relay says "Silicon Power Cube" on it and is rated for 240V and 3A. I am using it on 120VAC. The control voltage is specified at 3 to 32 VDC. This system works perfectly. I have been using common 20 inch box fans. The problem is they only last a year or so and then they just stop working. Sometimes they fail over the winter when they never run. I have tried to troubleshoot the fans but can't find out why they have failed. The capacitors on the motor measure the correct value. I suspect there is something in the SS relay that is causing them to fail but I have no idea how. Are SS relays compatible with induction motors? I am on my fourth fan in about 5 years now and these fans usually last forever. > Thanks for any ideas. > Soartech If you are refiring to the generic cheap window fans you get in the store, I find for the most part, they only last a year anyway.. You must check to see how stiff the rotor is, many times the bushings will dry out from the heat. Also after some run time the bushings will loosen up and when this happens, dust in the area will migrate its way into the bushings, what you normally end up with is a fan that worked last year but now is having a hard time starting, due to drag. These box fans operate hot anyway, due to their design. You may want to think about getting a real vent fan for agricalture, a motor type design to last in plases like chicken coops etc... P.S. Shop around at your local hardware store with a vent fan with this type of motor on it. Jamie |
| Phil Allison <pallison49@gmail.com>: May 30 07:54PM -0700 Gareth Magennis wrote: > for a music festival. > I was told by an electrician that you have to test these as Class 2, and put > a sticker on them to say so. ** That is completely insane crap. He must have been using illegal drugs to say such a thing and you are nuts to believe it. .... Phil |
| Phil Allison <pallison49@gmail.com>: May 31 12:14AM -0700 bud-- wrote: Phil Allison wrote: > > The only components that may be so connected are agency approved " Y caps " with values like 4.7nF - while MOVs and " X caps" always go across the line. > Standard practice in the US for plug-in protectors is MOVs from H-N, > H-G, N-G. ** I really doubt using three MOVs like that is *normal* practice - certainly one never sees it in entertainment electronics or test gear, whether made in the USA or elsewhere. > The normal failure mode for MOVs is after sufficient energy hits they > start to conduct at lower voltages, eventually conduct at 'normal' > voltages, and go into thermal runaway. ** The fact that MOVs deteriorate means it is hazardous to have them wired from active to safety ground. Same argument goes for regular metallised film capacitors which also deteriorate when exposed to AC supply voltages - then explode. > I would think a H-N MOV with 1mA leakage > @230V would be near thermal runaway. ** Takes at least 10mA to get a typical MOV device hot. .... Phil |
| bud-- <null@void.com>: May 31 08:38AM -0600 On 5/31/2015 1:14 AM, Phil Allison wrote: >> Standard practice in the US for plug-in protectors is MOVs from H-N, >> H-G, N-G. > ** I really doubt using three MOVs like that is *normal* practice - certainly one never sees it in entertainment electronics or test gear, whether made in the USA or elsewhere. Entertainment electronics may have some surge protection but is not intended to protect against major surges. As can be seen from the IEEE surge guide, 3 MOVs is absolutely standard practice in the US. Because of the additional risks added by having only H-N protection in plug-in protectors (as in my last post) I suspect 3 MOVs is common practice elsewhere, H-N only protectors can increase risk, not reduce it. Gareth does not know what is connected H-G. You do not necessarily know what the specific requirements are for plug-in protectors elsewhere. All the packaging protectors come in that I have seen indicate what the protection is (H-N, H-G, N-G). I suspect it would elsewhere. I am not interested in looking. >> start to conduct at lower voltages, eventually conduct at 'normal' >> voltages, and go into thermal runaway. > ** The fact that MOVs deteriorate means it is hazardous to have them wired from active to safety ground. Same argument goes for regular metallised film capacitors which also deteriorate when exposed to AC supply voltages - then explode. In the US the likely maximum surge energy at a MOV in a plug-in protector is a tiny 35J, and that includes for the largest probable power line surge (as in my 1st post). The simplest UL listed protector here will have a joule rating far above that. The joule rating of a MOV is the single event energy that will put the MOV at defined end of life (but still functional). Looking at MOV ratings curves, if the MOV gets single hits that are far below that, the cumulative rating is far above (like over 10x) the single event rating. Failure is real unlikely. Coupled with high ratings, that is why some companies can have protected equipment warranties. The author of the NIST surge guide has written "in fact, the major cause of [surge protector] failures is a temporary overvoltage, rather than an unusually large surge." An example of temporary overvoltage would be a high voltage distribution wire coming down on the 115/230V secondary conductors. You could also say it is hazardous to have leakage and fault currents on the safety ground. |
| Chris Jones <lugnut808@spam.yahoo.com>: May 31 11:53PM +1000 On 30/05/2015 16:59, Gareth Magennis wrote: At least some testers measure the insulation resistance (between live/neutral and earth) at either 500VDC or 250VDC. The 250V setting is labelled "MOV". This document explains the testing process: http://uk.megger.com/getmedia/a5f14a4f-e742-4e85-b7de-db02f5f9a533/PAT-Testing-surge-protected-equipment_AN_en_V01.pdf/ The note from Megger on testing these surge protectors above also seems to imply that connecting MOVs between live and earth is a common arrangement, however they show a gas discharge tube between the Earth wire and the MOVs. It would be interesting to know if this is common and if so, why and what are its ratings. Other pages seem to suggest that at least in some cases/countries, MOVs are connected directly from live to earth. http://en.wikipedia.org/wiki/Power_strip#Surge_protection_and_filtering http://www.racktronics.com.au/gallery.php http://badcaps.net/forum/showthread.php?p=10176 I'm not sure whether this is a good thing, unless you know for sure that your earth connections are all present and correct, and your RCD/ELCB is present and working. Whilst I would agree with Phil that a used MOV is likely to be so leaky as to result in unacceptable current flowing from live to earth, I'm not sure that many of the appliance standards would catch this, unless the sequence of tests (during product approval not PAT) would first damage and later test the leakage of the MOV. Chris |
| Phil Allison <pallison49@gmail.com>: May 31 07:11AM -0700 bud-- wrote: > > ** I really doubt using three MOVs like that is *normal* practice - certainly one never sees it in entertainment electronics or test gear, whether made in the USA or elsewhere. > Entertainment electronics may have some surge protection but is not > intended to protect against major surges. ** Nor are an plug-in surge protectors. You are bullshitting wildly. > As can be seen from the IEEE surge guide, 3 MOVs is absolutely standard > practice in the US. ** Really - you must send me a copy. Yawnnnnn.... > Because of the additional risks added by having only H-N protection in > plug-in protectors ** There is no risk that derives from the device itself - until you add MOVs to ground. You really need to pay attenion to the context. (as in my last post) I suspect 3 MOVs is common > practice elsewhere, ** What you "suspect" is on no value, at all, to anyone. > H-N only protectors can increase risk, not reduce it. ** Insane crap. > Gareth does not know what is connected H-G. ** Gareth is an even bigger bullshitter than you. > All the packaging protectors come in that I have seen indicate what the > protection is (H-N, H-G, N-G). I suspect it would elsewhere. I am not > interested in looking. ** ROTFL. > protector is a tiny 35J, and that includes for the largest probable > power line surge (as in my 1st post). The simplest UL listed protector > here will have a joule rating far above that. ** Another one of you wild suspicions ? > You could also say it is hazardous to have leakage and fault currents on > the safety ground. ** It is. You totally fail to see what the safety issue is. You have no understanding of why no ordinary or class X film caps of any value can be wired from line to safety ground, ONLY special class Y types are permitted in restricted values. True in the USA, the EU and elsewhere. ... Phil |
| bud-- <null@void.com>: May 31 09:26AM -0600 On 5/31/2015 7:53 AM, Chris Jones wrote: > however they show a gas discharge tube between the Earth > wire and the MOVs. It would be interesting to know if this is common and > if so, why and what are its ratings. As a guess, the GDT prevents leakage Phil is worried about, and the MOV prevents "follow-on" discharge through the GDT right after the surge is over and normal power is present. > Whilst I would agree with Phil that a used MOV is > likely to be so leaky as to result in unacceptable current flowing from > live to earth, As I responded to Phil, this is actually quite unlikely (at least in the US). > I'm not sure that many of the appliance standards would > catch this, unless the sequence of tests (during product approval not > PAT) would first damage and later test the leakage of the MOV. US-UL tests include a series of test surges, after which the device has to be functional (in particular, it is not 'leaking'). Later tests may cause the device to fail, but it must fail safely. |
| Phil Allison <pallison49@gmail.com>: May 31 07:43AM -0700 Chris Jones wrote: > labelled "MOV". > This document explains the testing process: > http://uk.megger.com/getmedia/a5f14a4f-e742-4e85-b7de-db02f5f9a533/PAT-Testing-surge-protected-equipment_AN_en_V01.pdf/ ** That note is dated *2014* and admits that PAT testers without a 250VDC setting cannot distinguish devices with MOVs to ground from faulty devices. This is not an acceptable situation. IIRC, the "Megger 4DV" that I saw had no such setting. > The note from Megger on testing these surge protectors above also seems > to imply that connecting MOVs between live and earth is a common > arrangement, ** So common that they noticed it only last year !!! Yawnnnnnnnnnnnnn..... > Other pages seem to suggest that at least in some cases/countries, MOVs > are connected directly from live to earth. ** Sure - in the USA, but only in some surge protectors. > likely to be so leaky as to result in unacceptable current flowing from > live to earth, I'm not sure that many of the appliance standards would > catch this, ** No need to "catch" it, the fitting of MOVs to ground inside a plug-in appliance is simply prohibited. The standard 500V DC leakage test would indicate the existence of a MOV wired to ground - if eyeballs were not able to. ... Phil |
| bud-- <null@void.com>: May 31 09:55AM -0600 On 5/31/2015 8:11 AM, Phil Allison wrote: >> practice in the US. > ** Really - you must send me a copy. > Yawnnnnn.... Link to the IEEE surge guide was in my first post. Excellent information from a completely reliable source. If you read it you might learn something. >> H-N only protectors can increase risk, not reduce it. > ** Insane crap. The problem I described, with 3 MOV protectors, is well know and in a published research paper by the author of the NIST surge guide (guide is also linked in my 1st post). Problems with using only a H-N MOV are considerably greater. The fix in the paper was to run not just power wires, but also signal wires through the protector with the voltage limited from all wires to the ground at the protector (as also described starting page 30 in the IEEE surge guide, which is linked-to in my 1st post). >> power line surge (as in my 1st post). The simplest UL listed protector >> here will have a joule rating far above that. > ** Another one of you wild suspicions ? Published research by the author of the NIST surge guide , who was the US-NIST surge expert. My information comes from the IEEE, the NIST, and published research. Sometimes you post really interesting information. Sometimes not. This is one of the latter. |
| Tim Schwartz <tim@bristolnj.com>: May 31 08:03AM -0400 On 5/29/2015 9:37 AM, Ed Tom wrote: > Hi, Can you help with a diagram for the threading of the rubber belt on the > Aiwa NSX 999 tape decks? Tks for yr anticipated help. Ed, If you mean replacing the belt without taking the mechanism apart, you probably can't. In general you'd have to take the mechanism out of the chassis, and usually have to remove at least the capstan flywheel thrust bearing. Most belts don't thread in. While I don't know your specific model, most cassette transports have the belts installed during assembly. You'll have to look at the service manual for your model to be sure. It often can take a couple of hours, even if you done this many times before. Regards, Tim |
| afonsogageiro@gmail.com: May 30 11:21AM -0700 Probably from 88 or 89. Don't have a camera handy but here's a video of it: https://m.youtube.com/watch?v=FWWn_IK_PmU Best regards, Afonso Gageiro |
| Bruce Esquibel <bje@ripco.com>: May 31 11:54AM > Where is the tuning button (or equivalent) on a National L15EN VCR? I can't find it anywhere! > Best regards, > Afonso Gageiro I don't know for sure but do you have the remote? I'd guess if there is no obvious programming button on the machine, there must be something on the remote or a on-screen-menu, if it has those. It wasn't a vcr but the last crt-type tv I bought (a phillips with built-in vcr and dvd player), the channel setup was buried in a on-screen-menu somewhere, which if I remember correctly, was not available with any of the push buttons on the set. Best guess I have. -bruce bje@ripco.com |
| M Philbrook <jamie_ka1lpa@charter.net>: May 30 01:04PM -0400 In article <mk9uua$u5e$1@dont-email.me>, nojunk@knology.net says... > button, huh, it works. Hard to fix it when it works. > We'll see how long this lasts. :-) > Mikek It's just smarter than you, you only need the remote while in the truck! When you're out of the truck it's obvious you should be able to open the door yourself! Come on man, it's simple logic. Jamie |
| amdx <nojunk@knology.net>: May 30 12:58PM -0500 On 5/30/2015 12:04 PM, M Philbrook wrote: > to open the door yourself! > Come on man, it's simple logic. > Jamie I can't argue with logic. It's still working. Mikek PS. I have solved the sooty area, at least to my thinking. The transistor that runs hot, caused the PCB to turn slightly brown, I also created a chimney effect causing the air and it's contaminates to rise to about an inch and deposit the contaminates on the white plastic connector |
| M Philbrook <jamie_ka1lpa@charter.net>: May 30 10:21PM -0400 In article <mkctn3$oi4$1@dont-email.me>, nojunk@knology.net says... > I also created a chimney effect causing the air and it's contaminates to > rise to about an inch and deposit the contaminates on the white plastic > connector Sounds like a bad Tranny or a bad design.. If the tranny has lost some of the beta, it could operate hot and just barely enough to do the job it's in there for, may even not work at times. I would think if it's a design issue there should be references to it all over the net, you can't hide things like that, people like to talk about the bad things no matter who did it :). Talking about good things is simply boring ! jamie |
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